mirror of https://github.com/docker/docs.git
Fixing problems with the instructions
Updating the application after test Removing the sudo as it caused issues Adding new screen shots Breaking into several files/sections Adding in the alias from the old single page version Moving to old path to avoid an alias Adding in Dong's comments Updating with latest fixes Fixing nits and more Signed-off-by: Mary Anthony <mary@docker.com>
This commit is contained in:
Mary Anthony
parent
7f6f9e518c
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@ -12,7 +12,17 @@ weight=-75
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|
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# Docker Swarm
|
# Docker Swarm
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||||||
|
|
||||||
- [Docker Swarm overview](overview.md)
|
* [Docker Swarm overview](overview.md)
|
||||||
- [Scheduler strategies](scheduler/strategy.md)
|
* [How to get Docker Swarm](get-swarm.md)
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||||||
- [Scheduler filters](scheduler/filter.md)
|
* [Evaluate Swarm in a sandbox](install-w-machine.md)
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- [Swarm API](swarm-api.md)
|
* [Plan for Swarm in production](plan-for-production.md)
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|
* [Build a Swarm cluster for production](install-manual.md)
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||||||
|
* [Try Swarm at scale](swarm_at_scale/index.md)
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||||||
|
* [Overview Swarm with TLS](secure-swarm-tls.md)
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||||||
|
* [Configure Docker Swarm for TLS](configure-tls.md)
|
||||||
|
* [Docker Swarm Discovery](discovery.md)
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|
* [High availability in Docker Swarm](multi-manager-setup.md)
|
||||||
|
* [Swarm and container networks](networking.md)
|
||||||
|
* [Advanced Scheduling](scheduler/index.md)
|
||||||
|
* [Provision a Swarm cluster with Docker Machine](provision-with-machine.md)
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||||||
|
* [Docker Swarm API](swarm-api.md)
|
||||||
|
|
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|
|
@ -62,7 +62,7 @@ the [Docker remote
|
||||||
API](http://docs.docker.com/reference/api/docker_remote_api/), and extends it
|
API](http://docs.docker.com/reference/api/docker_remote_api/), and extends it
|
||||||
with some new endpoints.
|
with some new endpoints.
|
||||||
|
|
||||||
# Getting help
|
## Getting help
|
||||||
|
|
||||||
Docker Swarm is still in its infancy and under active development. If you need
|
Docker Swarm is still in its infancy and under active development. If you need
|
||||||
help, would like to contribute, or simply want to talk about the project with
|
help, would like to contribute, or simply want to talk about the project with
|
||||||
|
|
|
||||||
|
|
@ -346,7 +346,7 @@ planning, deployment, and ongoing management of your production Swarm clusters.
|
||||||
|
|
||||||
## Related information
|
## Related information
|
||||||
|
|
||||||
* [Try Swarm at scale](swarm_at_scale.md)
|
* [Try Swarm at scale](swarm_at_scale/index.md)
|
||||||
* [Swarm and container networks](networking.md)
|
* [Swarm and container networks](networking.md)
|
||||||
* [High availability in Docker Swarm](multi-manager-setup.md)
|
* [High availability in Docker Swarm](multi-manager-setup.md)
|
||||||
* [Universal Control plane](https://www.docker.com/products/docker-universal-control-plane)
|
* [Universal Control plane](https://www.docker.com/products/docker-universal-control-plane)
|
||||||
|
|
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||||||
|
|
@ -1,771 +0,0 @@
|
||||||
<!--[metadata]>
|
|
||||||
+++
|
|
||||||
title = "Try Swarm at scale"
|
|
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description = "Try Swarm at scale"
|
|
||||||
keywords = ["docker, swarm, scale, voting, application, certificates"]
|
|
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[menu.main]
|
|
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parent="workw_swarm"
|
|
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weight=-35
|
|
||||||
+++
|
|
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<![end-metadata]-->
|
|
||||||
|
|
||||||
# Try Swarm at scale
|
|
||||||
|
|
||||||
Using this example, you'll deploy a voting application on a Swarm cluster. The
|
|
||||||
example walks you through creating a Swarm cluster and deploying the application
|
|
||||||
against the cluster. This walk through is intended to illustrate one example of
|
|
||||||
a typical development process.
|
|
||||||
|
|
||||||
After building and manually deploying the voting application, you'll construct a
|
|
||||||
Docker Compose file. You (or others) can use the file to deploy and scale the
|
|
||||||
application further. The article also provides a troubleshooting section you can
|
|
||||||
use while developing or deploying the voting application.
|
|
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|
|
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|
|
||||||
## About the example
|
|
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|
|
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Your company is a pet food company that has bought an commercial during the
|
|
||||||
Superbowl. The commercial drives viewers to a web survey that asks users to vote – cats or dogs. You are developing the web survey. Your survey must ensure that
|
|
||||||
millions of people can vote concurrently without your website becoming
|
|
||||||
unavailable. You don't need real-time results, a company press release announces
|
|
||||||
the results. However, you do need confidence that every vote is counted.
|
|
||||||
|
|
||||||
The example assumes you are deploying the application to a Docker Swarm cluster
|
|
||||||
running on top of Amazon Web Services (AWS). AWS is an example only. There is
|
|
||||||
nothing about this application or deployment that requires it. You could deploy
|
|
||||||
the application to a Docker Swarm cluster running on; a different cloud provider
|
|
||||||
such as Microsoft Azure, on premises in your own physical data center, or in a
|
|
||||||
development environment on your laptop.
|
|
||||||
|
|
||||||
The example requires you to perform the following high-level steps:
|
|
||||||
|
|
||||||
- [Deploy your infrastructure](#deploy-your-infrastructure)
|
|
||||||
- [Create the Swarm cluster](#create-the-swarm-cluster)
|
|
||||||
- [Overlay a container network on the cluster](#overlay-a-container-network-on-the-cluster)
|
|
||||||
- [Deploy the voting application](#deploy-the-voting-application)
|
|
||||||
- [Test the application](#test-the-application)
|
|
||||||
|
|
||||||
Before working through the sample, make sure you understand the application and Swarm cluster architecture.
|
|
||||||
|
|
||||||
### Application architecture
|
|
||||||
|
|
||||||
The voting application is a Dockerized microservice application. It uses a
|
|
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parallel web frontend that sends jobs to asynchronous background workers. The
|
|
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application's design can accommodate arbitrarily large scale. The diagram below
|
|
||||||
shows the high level architecture of the application.
|
|
||||||
|
|
||||||
|
|
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|
|
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The application is fully Dockerized with all services running inside of
|
|
||||||
containers.
|
|
||||||
|
|
||||||
The frontend consists of an Interlock load balancer with *n* frontend web
|
|
||||||
servers and associated queues. The load balancer can handle an arbitrary number
|
|
||||||
of web containers behind it (`frontend01`- `frontendN`). The web containers run
|
|
||||||
a simple Python Flask application. Each container accepts votes and queues them
|
|
||||||
to a Redis container on the same node. Each web container and Redis queue pair
|
|
||||||
operates independently.
|
|
||||||
|
|
||||||
The load balancer together with the independent pairs allows the entire
|
|
||||||
application to scale to an arbitrary size as needed to meet demand.
|
|
||||||
|
|
||||||
Behind the frontend is a worker tier which runs on separate nodes. This tier:
|
|
||||||
|
|
||||||
* scans the Redis containers
|
|
||||||
* dequeues votes
|
|
||||||
* deduplicates votes to prevent double voting
|
|
||||||
* commits the results to a Postgres container running on a separate node
|
|
||||||
|
|
||||||
Just like the front end, the worker tier can also scale arbitrarily.
|
|
||||||
|
|
||||||
### Swarm Cluster Architecture
|
|
||||||
|
|
||||||
To support the application the design calls for a Swarm cluster that with a single Swarm manager and 4 nodes as shown below.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
All four nodes in the cluster are running the Docker daemon, as is the Swarm
|
|
||||||
manager and the Interlock load balancer. The Swarm manager exists on a Docker
|
|
||||||
host that is not part of the cluster and is considered out of band for the
|
|
||||||
application. The Interlock load balancer could be placed inside of the cluster,
|
|
||||||
but for this demonstration it is not.
|
|
||||||
|
|
||||||
The diagram below shows the application architecture overlayed on top of the
|
|
||||||
Swarm cluster architecture. After completing the example and deploying your
|
|
||||||
application, this is what your environment should look like.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
As the previous diagram shows, each node in the cluster runs the following containers:
|
|
||||||
|
|
||||||
- `frontend01`:
|
|
||||||
- Container: Python flask web app (frontend01)
|
|
||||||
- Container: Redis (redis01)
|
|
||||||
- `frontend02`:
|
|
||||||
- Container: Python flask web app (frontend02)
|
|
||||||
- Container: Redis (redis02)
|
|
||||||
- `worker01`: vote worker app (worker01)
|
|
||||||
- `store`:
|
|
||||||
- Container: Postgres (pg)
|
|
||||||
- Container: results app (results-app)
|
|
||||||
|
|
||||||
## Deploy your infrastructure
|
|
||||||
|
|
||||||
As previously stated, this article will walk you through deploying the
|
|
||||||
application to a Swam cluster in an AWS Virtual Private Cloud (VPC). However,
|
|
||||||
you can reproduce the environment design on whatever platform you wish. For
|
|
||||||
example, you could place the application on another public cloud platform such
|
|
||||||
as DigitalOcean, on premises in your data center, or even in in a test
|
|
||||||
environment on your laptop.
|
|
||||||
|
|
||||||
Deploying the AWS infrastructure requires that you first build the VPC and then
|
|
||||||
apply apply the [CloudFormation
|
|
||||||
template](https://github.com/docker/swarm-microservice-demo-v1/blob/master/AWS/cloudformation.json).
|
|
||||||
While you cloud create the entire VPC and all instances via a CloudFormation
|
|
||||||
template, splitting the deployment into two steps allows the CloudFormation
|
|
||||||
template to be easily used to build instances in *existing VPCs*.
|
|
||||||
|
|
||||||
The diagram below shows the VPC infrastructure required to run the
|
|
||||||
CloudFormation template.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
The AWS configuration is a single VPC with a single public subnet. The VPC must
|
|
||||||
be in the `us-west-1` Region (N. California). This Region is required for this
|
|
||||||
particular CloudFormation template to work. The VPC network address space is
|
|
||||||
`192.168.0.0/16` and single 24-bit public subnet is carved out as
|
|
||||||
192.168.33.0/24. The subnet must be configured with a default route to the
|
|
||||||
internet via the VPC's internet gateway. All 6 EC2 instances are deployed into
|
|
||||||
this public subnet.
|
|
||||||
|
|
||||||
Once the VPC is created you can deploy the EC2 instances using the
|
|
||||||
CloudFormation template located
|
|
||||||
[here](https://github.com/docker/swarm-microservice-demo-v1/blob/master/AWS/cloudformation.json).
|
|
||||||
|
|
||||||
>**Note**: If you are not deploying to AWS, or are not using the CloudFormation template mentioned above, make sure your Docker hosts are running a 3.16 or higher kernel. This kernel is required by Docker's container networking feature.
|
|
||||||
|
|
||||||
### Step 1. Build and configure the VPC
|
|
||||||
|
|
||||||
This step assumes you know how to configure a VPC either manually
|
|
||||||
or using the VPC wizard on Amazon. You can build the VPC manually or by using
|
|
||||||
using the VPC Wizard. If you use the wizard, be sure to choose the **VPC with a
|
|
||||||
Single Public Subnet** option.
|
|
||||||
|
|
||||||
Configure your VPC with the following values:
|
|
||||||
|
|
||||||
- **Region**: N. California (us-west-1)
|
|
||||||
- **VPC Name**: Swarm-scale
|
|
||||||
- **VPC Network (CIDR)**: 192.168.0.0/16
|
|
||||||
- **DNS resolution**: Yes
|
|
||||||
- **Subnet name**: PublicSubnet
|
|
||||||
- **Subnet type**: Public (with route to the internet)
|
|
||||||
- **Subnet network (CIDR)**: 192.168.33.0/24
|
|
||||||
- **Auto-assign public IP**: Yes
|
|
||||||
- **Availability Zone**: Any
|
|
||||||
- **Router**: A single router with a route for *local* traffic and default route for traffic to the internet
|
|
||||||
- **Internet gateway**: A single internet gateway used as default route for the subnet's routing table
|
|
||||||
|
|
||||||
You'll configure the remaining AWS settings in the next section as part of the
|
|
||||||
CloudFormation template.
|
|
||||||
|
|
||||||
|
|
||||||
### Step 2. Apply the CloudFormation template
|
|
||||||
|
|
||||||
Before you can apply the CloudFormation template, you will need to have created
|
|
||||||
a VPC as per instructions in the previous section. You will also need access to
|
|
||||||
the private key of an EC2 KeyPair associated with your AWS account in the
|
|
||||||
`us-west-1` Region. Follow the steps below to build the remainder of the AWS
|
|
||||||
infrastructure using the CloudFormation template.
|
|
||||||
|
|
||||||
1. Choose **Create Stack** from the CloudFormation page in the AWS Console
|
|
||||||
2. Click the **Choose file** button under the **Choose a template** section
|
|
||||||
3. Select the **swarm-scale.json** CloudFormation template available from the [application's GitHub repo](https://github.com/docker/swarm-microservice-demo-v1/blob/master/AWS/cloudformation.json)
|
|
||||||
4. Click **Next**
|
|
||||||
5. Give the Stack a name. You can name the stack whatever you want, though it is recommended to use a meaningful name
|
|
||||||
6. Select a KeyPair form the dropdown list
|
|
||||||
7. Select the correct **Subnetid** (PublicSubnet) and **Vpcid** (SwarmCluster) from the dropdowns
|
|
||||||
8. Click **Next**
|
|
||||||
9. Click **Next** again
|
|
||||||
10. Review your settings and click **Create**
|
|
||||||
AWS displays the progress of your stack being created
|
|
||||||
|
|
||||||
### Step 3. Check your deployment
|
|
||||||
|
|
||||||
When completed, the CloudFormation populates your VPC with the following six EC2 instances:
|
|
||||||
|
|
||||||
- `manager`: t2.micro / 192.168.33.11
|
|
||||||
- `interlock`: t2.micro / 192.168.33.12
|
|
||||||
- `frontend01`: t2.micro / 192.168.33.20
|
|
||||||
- `frontend02`: t2.micro / 192.168.33.21
|
|
||||||
- `worker01`: t2.micro / 192.168.33.200
|
|
||||||
- `store`: m3.medium / 192.168.33.250
|
|
||||||
|
|
||||||
Your AWS infrastructure should look like this.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
All instances are based on the `ami-56f59e36` AMI. This is an Ubuntu 14.04
|
|
||||||
image with a 3.16 kernel and 1.9.1 of the Docker Engine installed. It also has
|
|
||||||
the following parameters added to the `DOCKER_OPTS` line in
|
|
||||||
`/etc/default/docker`:
|
|
||||||
|
|
||||||
```
|
|
||||||
--cluster-store=consul://192.168.33.11:8500 --cluster-advertise=eth0:2375 -H=tcp://0.0.0.0:2375 -H=unix:///var/run/docker.sock\
|
|
||||||
```
|
|
||||||
|
|
||||||
Once your stack is created successfully you are ready to progress to the next
|
|
||||||
step and build the Swarm cluster. From this point, the instructions refer to the
|
|
||||||
AWS EC2 instances as "nodes".
|
|
||||||
|
|
||||||
## Create the Swarm cluster
|
|
||||||
|
|
||||||
Now that your underlying network infrastructure is built, you are ready to build and configure the Swarm cluster.
|
|
||||||
|
|
||||||
### Step 1: Construct the cluster
|
|
||||||
|
|
||||||
The steps below construct a Swarm cluster by:
|
|
||||||
|
|
||||||
* using Consul as the discovery backend
|
|
||||||
* join the `frontend`, `worker`
|
|
||||||
* `store` EC2 instances to the cluster
|
|
||||||
* use the `spread` scheduling strategy.
|
|
||||||
|
|
||||||
Perform all of the following commands from the `manager` node.
|
|
||||||
|
|
||||||
1. Start a new Consul container that listens on TCP port 8500
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped -d -p 8500:8500 -h consul progrium/consul -server -bootstrap
|
|
||||||
|
|
||||||
This starts a Consul container for use as the Swarm discovery service. This
|
|
||||||
backend is also used as the K/V store for the container network that you
|
|
||||||
overlay on the Swarm cluster in a later step.
|
|
||||||
|
|
||||||
2. Start a Swarm manager container.
|
|
||||||
|
|
||||||
This command maps port 3375 on the `manager` node to port 2375 in the
|
|
||||||
Swarm manager container
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped -d -p 3375:2375 swarm manage consul://192.168.33.11:8500/
|
|
||||||
|
|
||||||
This Swarm manager container is the heart of your Swarm cluster. It is
|
|
||||||
responsible for receiving all Docker commands sent to the cluster, and for
|
|
||||||
scheduling resources against the cluster. In a real-world production
|
|
||||||
deployment you would configure additional replica Swarm managers as
|
|
||||||
secondaries for high availability (HA).
|
|
||||||
|
|
||||||
3. Set the `DOCKER_HOST` environment variable.
|
|
||||||
|
|
||||||
This ensures that the default endpoint for Docker commands is the Docker daemon running on the `manager` node
|
|
||||||
|
|
||||||
$ export DOCKER_HOST="tcp://192.168.33.11:3375"
|
|
||||||
|
|
||||||
4. While still on the `manager` node, join the nodes to the cluster.
|
|
||||||
|
|
||||||
You can run these commands form the `manager` node because the `-H` flag
|
|
||||||
sends the commands to the Docker daemons on the nodes. The command joins a
|
|
||||||
node to the cluster and registers it with the Consul discovery service.
|
|
||||||
|
|
||||||
sudo docker -H=tcp://<node-private-ip>:2375 run -d swarm join --advertise=<node-private-ip>:2375 consul://192.168.33.11:8500/
|
|
||||||
|
|
||||||
Substitute `<node-private-ip` in the command with the private IP of the
|
|
||||||
you are adding. Repeat step 4 for every node you are adding to the cluster -
|
|
||||||
`frontend01`, `frontend02`, `worker01`, and `store`.
|
|
||||||
|
|
||||||
|
|
||||||
### Step 2: Review your work
|
|
||||||
|
|
||||||
The diagram below shows the Swarm cluster that you created.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
The diagram shows the `manager` node is running two containers: `consul` and
|
|
||||||
`swarm`. The `consul` container is providing the Swarm discovery service. This
|
|
||||||
is where nodes and services register themselves and discover each other. The
|
|
||||||
`swarm` container is running the `swarm manage` process which makes it act as
|
|
||||||
the cluster manager. The manager is responsible for accepting Docker commands
|
|
||||||
issued against the cluster and scheduling resources on the cluster.
|
|
||||||
|
|
||||||
You mapped port 3375 on the `manager` node to port 2375 inside the `swarm`
|
|
||||||
container. As a result, Docker clients (for example the CLI) wishing to issue
|
|
||||||
commands against the cluster must send them to the `manager` node on port
|
|
||||||
3375. The `swarm` container then executes those commands against the relevant
|
|
||||||
node(s) in the cluster over port 2375.
|
|
||||||
|
|
||||||
Now that you have your Swarm cluster configured, you'll overlay the container
|
|
||||||
network that the application containers will be part of.
|
|
||||||
|
|
||||||
## Overlay a container network on the cluster
|
|
||||||
|
|
||||||
All containers that are part of the voting application belong to a container
|
|
||||||
network called `mynet`. This will be an overlay network that allows all
|
|
||||||
application containers to easily communicate irrespective of the underlying
|
|
||||||
network that each node is on.
|
|
||||||
|
|
||||||
### Step 1: Create the network
|
|
||||||
|
|
||||||
You can create the network and join the containers from any node in your VPC
|
|
||||||
that is running Docker Engine. However, best practice when using Docker Swarm is
|
|
||||||
to execute commands from the `manager` node, as this is where all management
|
|
||||||
tasks happen.
|
|
||||||
|
|
||||||
1. Open a terminal on your `manager` node.
|
|
||||||
2. Create the overlay network with the `docker network` command
|
|
||||||
|
|
||||||
$ sudo docker network create --driver overlay mynet
|
|
||||||
|
|
||||||
An overlay container network is visible to all Docker daemons that use the
|
|
||||||
same discovery backend. As all Swarm nodes in your environment are
|
|
||||||
configured to use the Consul discovery service at
|
|
||||||
`consul://192.168.33.11:8500`, they all should see the new overlay network.
|
|
||||||
Verify this with the next step.
|
|
||||||
|
|
||||||
3. Log onto each node in your Swarm cluster and verify the `mynet` network is running.
|
|
||||||
|
|
||||||
$ sudo docker network ls
|
|
||||||
NETWORK ID NAME DRIVER
|
|
||||||
72fa20d0663d mynet overlay
|
|
||||||
bd55c57854b8 host host
|
|
||||||
25e34427f6ff bridge bridge
|
|
||||||
8eee5d2130ab none null
|
|
||||||
|
|
||||||
You should see an entry for the `mynet` network using the `overlay` driver as shown above.
|
|
||||||
|
|
||||||
### Step 2: Review your work
|
|
||||||
|
|
||||||
The diagram below shows the complete cluster configuration including the overlay
|
|
||||||
container network, `mynet`. The `mynet` is shown as red and is available to all
|
|
||||||
Docker hosts using the Consul discovery backend. Later in the procedure you will
|
|
||||||
connect containers to this network.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
> **Note**: The `swarm` and `consul` containers on the `manager` node are not attached to the `mynet` overlay network.
|
|
||||||
|
|
||||||
Your cluster is now built and you are ready to build and run your application on
|
|
||||||
it.
|
|
||||||
|
|
||||||
## Deploy the voting application
|
|
||||||
|
|
||||||
Now it's time to configure the application.
|
|
||||||
|
|
||||||
Some of the containers in the application are launched from custom images you
|
|
||||||
must build. Others are launched form existing images pulled directly from Docker
|
|
||||||
Hub. Deploying the application requires that you:
|
|
||||||
|
|
||||||
- Understand the custom images
|
|
||||||
- Build custom images
|
|
||||||
- Pull stock images from Docker Hub
|
|
||||||
- Launch application containers
|
|
||||||
|
|
||||||
### Step 1: Understand the custom images
|
|
||||||
|
|
||||||
The list below shows which containers use custom images and which do not:
|
|
||||||
|
|
||||||
- Web containers: custom built image
|
|
||||||
- Worker containers: custom built image
|
|
||||||
- Results containers: custom built image
|
|
||||||
- Load balancer container: stock image (`ehazlett/interlock`)
|
|
||||||
- Redis containers: stock image (official `redis` image)
|
|
||||||
- Postgres (PostgreSQL) containers: stock image (official `postgres` image)
|
|
||||||
|
|
||||||
All custom built images are built using Dockerfile's pulled from the [application's public GitHub repository](https://github.com/docker/swarm-microservice-demo-v1).
|
|
||||||
|
|
||||||
1. Log into the Swarm manager node.
|
|
||||||
2. Clone the [application's GitHub repo](https://github.com/docker/swarm-microservice-demo-v1)
|
|
||||||
|
|
||||||
$ sudo git clone https://github.com/docker/swarm-microservice-demo-v1
|
|
||||||
|
|
||||||
This command creates a new directory structure inside of your working
|
|
||||||
directory. The new directory contains all of the files and folders required
|
|
||||||
to build the voting application images.
|
|
||||||
|
|
||||||
The `AWS` directory contains the `cloudformation.json` file used to deploy
|
|
||||||
the EC2 instances. The `Vagrant` directory contains files and instructions
|
|
||||||
required to deploy the application using Vagrant. The `results-app`,
|
|
||||||
`vote-worker`, and `web-vote-app` directories contain the Dockerfiles and
|
|
||||||
other files required to build the custom images for those particular
|
|
||||||
components of the application.
|
|
||||||
|
|
||||||
|
|
||||||
3. Change directory into the `swarm-microservice-demo-v1/web-vote-app` directory and inspect the contents of the `Dockerfile`
|
|
||||||
|
|
||||||
$ cd swarm-microservice-demo-v1/web-vote-app/
|
|
||||||
|
|
||||||
$ cat Dockerfile
|
|
||||||
FROM python:2.7
|
|
||||||
WORKDIR /app
|
|
||||||
ADD requirements.txt /app/requirements.txt
|
|
||||||
RUN pip install -r requirements.txt
|
|
||||||
ADD . /app
|
|
||||||
EXPOSE 80
|
|
||||||
CMD ["python", "app.py"]
|
|
||||||
|
|
||||||
As you can see, the image is based on the official `Python:2.7` tagged
|
|
||||||
image, adds a requirements file into the `/app` directory, installs
|
|
||||||
requirements, copies files from the build context into the container,
|
|
||||||
exposes port `80` and tells the container which command to run.
|
|
||||||
|
|
||||||
### Step 2. Build custom images
|
|
||||||
|
|
||||||
1. Log into the swarm manager node if you haven't already.
|
|
||||||
2. Change to the root of your swarm-demo-voting app clone.
|
|
||||||
|
|
||||||
2. Build the `web-votes-app` image on `frontend01` and `frontend02`
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.20:2375 build -t web-vote-app ./web-vote-app
|
|
||||||
$ sudo docker -H tcp://192.168.33.21:2375 build -t web-vote-app ./web-vote-app
|
|
||||||
|
|
||||||
These commands build the `web-vote-app` image on the `frontend01` and
|
|
||||||
`frontend02` nodes. To accomplish the operation, each command copies the
|
|
||||||
contents of the `swarm-microservice-demo-v1/web-vote-app` sub-directory from the
|
|
||||||
`manager` node to each frontend node. The command then instructs the
|
|
||||||
Docker daemon on each frontend node to build the image and store it locally.
|
|
||||||
|
|
||||||
It may take a minute or so for each image to build. Wait for the builds to finish.
|
|
||||||
|
|
||||||
3. Build `vote-worker` image on the `worker01` node
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.200:2375 build -t vote-worker ./vote-worker
|
|
||||||
|
|
||||||
It may take a minute or so for the image to build. Wait for the build to finish.
|
|
||||||
|
|
||||||
5. Build the `results app` on the `store` node
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.250:2375 build -t results-app ./results-app
|
|
||||||
|
|
||||||
Each of the *custom images* required by the application is now built and stored locally on the nodes that will use them.
|
|
||||||
|
|
||||||
### Step 3. Pull stock images from Docker Hub
|
|
||||||
|
|
||||||
For performance reasons, it is always better to pull any required Docker Hub images locally on each instance that needs them. This ensures that containers based on those images can start quickly.
|
|
||||||
|
|
||||||
1. Log into the Swarm `manager` node.
|
|
||||||
|
|
||||||
2. Pull the `redis` image to `frontend01` and `frontend02`
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.20:2375 pull redis
|
|
||||||
$ sudo docker -H tcp://192.168.33.21:2375 pull redis
|
|
||||||
|
|
||||||
2. Pull the `postgres` image to the `store` node
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.250:2375 pull postgres
|
|
||||||
|
|
||||||
3. Pull the `ehazlett/interlock` image to the `interlock` node
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.12:2375 pull ehazlett/interlock
|
|
||||||
|
|
||||||
Each node in the cluster, as well as the `interlock` node, now has the required images stored locally as shown below.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
Now that all images are built, pulled, and stored locally, the next step is to start the application.
|
|
||||||
|
|
||||||
### Step 4. Start the voting application
|
|
||||||
|
|
||||||
The following steps will guide you through the process of starting the application
|
|
||||||
|
|
||||||
* Start the `interlock` load balancer container on `interlock`
|
|
||||||
* Start the `redis` containers on `frontend01` and `frontend02`
|
|
||||||
* Start the `web-vote-app` containers on `frontend01` and `frontend02`
|
|
||||||
* Start the `postgres` container on `store`
|
|
||||||
* Start the `worker` container on `worker01`
|
|
||||||
* Start the `results-app` container on `store`
|
|
||||||
|
|
||||||
Do the following:
|
|
||||||
|
|
||||||
1. Log into the Swarm `manager` node.
|
|
||||||
|
|
||||||
2. Start the `interlock` container on the `interlock` node
|
|
||||||
|
|
||||||
$ sudo docker -H tcp://192.168.33.12:2375 run --restart=unless-stopped -p 80:80 --name interlock -d ehazlett/interlock --swarm-url tcp://192.168.33.11:3375 --plugin haproxy start
|
|
||||||
|
|
||||||
This command is issued against the `interlock` instance and maps port 80 on the instance to port 80 inside the container. This allows the container to load balance connections coming in over port 80 (HTTP). The command also applies the `--restart=unless-stopped` policy to the container, telling Docker to restart the container if it exits unexpectadly.
|
|
||||||
|
|
||||||
2. Start a `redis` container on `frontend01` and `frontend02`
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==frontend01" -p 6379:6379 --name redis01 --net mynet -d redis
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==frontend02" -p 6379:6379 --name redis02 --net mynet -d redis
|
|
||||||
|
|
||||||
These two commands are issued against the Swarm cluster. The commands specify *node constraints*, forcing Swarm to start the contaienrs on `frontend01` and `frontend02`. Port 6379 on each instance is mapped to port 6379 inside of each container for debugging purposes. The command also applies the `--restart=unless-stopped` policy to the containers and attaches them to the `mynet` overlay network.
|
|
||||||
|
|
||||||
3. Start a `web-vote-app` container on `frontend01` and `frontend02`
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==frontend01" -d -p 5000:80 -e WEB_VOTE_NUMBER='01' --name frontend01 --net mynet --hostname votingapp.local web-vote-app
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==frontend02" -d -p 5000:80 -e WEB_VOTE_NUMBER='02' --name frontend02 --net mynet --hostname votingapp.local web-vote-app
|
|
||||||
|
|
||||||
These two commands are issued against the Swarm cluster. The commands specify *node constraints*, forcing Swarm to start the contaienrs on `frontend01` and `frontend02`. Port 5000 on each node is mapped to port 80 inside of each container. This allows connections to come in to each node on port 5000 and be forwarded to port 80 inside of each container. Both containers are attached to the `mynet` overlay network and both containers are given the `votingapp-local` hostname. The `--restart=unless-stopped` policy is also applied to these containers.
|
|
||||||
|
|
||||||
4. Start the `postgres` container on the `store` node
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==store" --name pg -e POSTGRES_PASSWORD=pg8675309 --net mynet -p 5432:5432 -d postgres
|
|
||||||
|
|
||||||
This command is issued against the Swarm cluster and starts the container on `store`. It maps port 5432 on the `store` node to port 5432 inside the container and attaches the container to the `mynet` overlay network. It also inserts the database password into the container via the POSTGRES_PASSWORD environment variable and applies the `--restart=unless-stopped` policy to the container. Sharing passwords like this is not recommended for production use cases.
|
|
||||||
|
|
||||||
5. Start the `worker01` container on the `worker01` node
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==worker01" -d -e WORKER_NUMBER='01' -e FROM_REDIS_HOST=1 -e TO_REDIS_HOST=2 --name worker01 --net mynet vote-worker
|
|
||||||
|
|
||||||
This command is issued against the Swarm manager and uses a constraint to start the container on the `worker01` node. It passes configuration data into the container via environment variables, telling the worker container to clear the queues on `frontend01` and `frontend02`. It adds the container to the `mynet` overlay network and applies the `--restart=unless-stopped` policy to the container.
|
|
||||||
|
|
||||||
6. Start the `results-app` container on the `store` node
|
|
||||||
|
|
||||||
$ sudo docker run --restart=unless-stopped --env="constraint:node==store" -p 80:80 -d --name results-app --net mynet results-app
|
|
||||||
|
|
||||||
This command starts the results-app container on the `store` node by means of a *node constraint*. It maps port 80 on the `store` node to port 80 inside the container. It adds the container to the `mynet` overlay network and applies the `--restart=unless-stopped` policy to the container.
|
|
||||||
|
|
||||||
The application is now fully deployed as shown in the diagram below.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
## Test the application
|
|
||||||
|
|
||||||
Now that the application is deployed and running, it's time to test it.
|
|
||||||
|
|
||||||
1. Configure a DNS mapping on your local machine for browsing.
|
|
||||||
|
|
||||||
You configure a DNS mapping on the machine where you are running your web browser. This maps the "votingapp.local" DNS name to the public IP address of the `interlock` node.
|
|
||||||
|
|
||||||
- On Windows machines this is done by adding `votingapp.local <interlock-public-ip>` to the `C:\Windows\System32\Drivers\etc\hosts file`. Modifying this file requires administrator privileges. To open the file with administrator privileges, right-click `C:\Windows\System32\notepad.exe` and select `Run as administrator`. Once Notepad is open, click `file` > `open` and open the file and make the edit.
|
|
||||||
- On OSX machines this is done by adding `votingapp.local <interlock-public-ip>` to `/private/etc/hosts`.
|
|
||||||
- On most Linux machines this is done by adding `votingapp.local <interlock-public-ip>` to `/etc/hosts`.
|
|
||||||
|
|
||||||
Be sure to replace <interlock-public-ip> with the public IP address of your `interlock` node. You can find the `interlock` node's Public IP by selecting your `interlock` EC2 Instance from within the AWS EC2 console.
|
|
||||||
|
|
||||||
2. Verify the mapping worked with a ping command from your web browsers machine
|
|
||||||
|
|
||||||
C:\Users\nigelpoulton>ping votingapp.local
|
|
||||||
Pinging votingapp.local [54.183.164.230] with 32 bytes of data:
|
|
||||||
Reply from 54.183.164.230: bytes=32 time=164ms TTL=42
|
|
||||||
Reply from 54.183.164.230: bytes=32 time=163ms TTL=42
|
|
||||||
Reply from 54.183.164.230: bytes=32 time=169ms TTL=42
|
|
||||||
|
|
||||||
3. Now that name resolution is configured and you have successfully pinged `votingapp.local`, point your web browser to [http://votingapp.local](http://votingapp.local)
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
Notice the text at the bottom of the web page. This shows which web
|
|
||||||
container serviced the request. In the diagram above, this is `frontend02`.
|
|
||||||
If you refresh your web browser you should see this change as the Interlock
|
|
||||||
load balancer shares incoming requests across both web containers.
|
|
||||||
|
|
||||||
To see more detailed load balancer data from the Interlock service, point your web browser to [http://stats:interlock@votingapp.local/haproxy?stats](http://stats:interlock@votingapp.local/haproxy?stats)
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
4. Cast your vote. It is recommended to choose "Dogs" ;-)
|
|
||||||
|
|
||||||
5. To see the results of the poll, you can point your web browser at the public IP of the `store` node
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
Congratulations. You have successfully walked through manually deploying a microservice-based application to a Swarm cluster.
|
|
||||||
|
|
||||||
## Troubleshooting the application
|
|
||||||
|
|
||||||
It's a fact of life that things fail. With this in mind, it's important to
|
|
||||||
understand what happens when failures occur and how to mitigate them. The
|
|
||||||
following sections cover different failure scenarios:
|
|
||||||
|
|
||||||
- [Swarm manager failures](#swarm-manager-failures)
|
|
||||||
- [Consul (discovery backend) failures](#consul-discovery-backend-failures)
|
|
||||||
- [Interlock load balancer failures](#interlock-load-balancer-failures)
|
|
||||||
- [Web (web-vote-app) failures](#web-web-vote-app-failures)
|
|
||||||
- [Redis failures](#redis-failures)
|
|
||||||
- [Worker (vote-worker) failures](#worker-vote-worker-failures)
|
|
||||||
- [Postgres failures](#postgres-failures)
|
|
||||||
- [Results-app failures](#results-app-failures)
|
|
||||||
- [Infrastructure failures](#infrastructure-failures)
|
|
||||||
|
|
||||||
### Swarm manager failures
|
|
||||||
|
|
||||||
In it's current configuration, the Swarm cluster only has single manager
|
|
||||||
container running on a single node. If the container exits or the node fails,
|
|
||||||
you will not be able to administer the cluster until you either; fix it, or
|
|
||||||
replace it.
|
|
||||||
|
|
||||||
If the failure is the Swarm manager container unexpectedly exiting, Docker will
|
|
||||||
automatically attempt to restart it. This is because the container was started
|
|
||||||
with the `--restart=unless-stopped` switch.
|
|
||||||
|
|
||||||
While the Swarm manager is unavailable, the application will continue to work in
|
|
||||||
its current configuration. However, you will not be able to provision more nodes
|
|
||||||
or containers until you have a working Swarm manager.
|
|
||||||
|
|
||||||
Docker Swarm supports high availability for Swarm managers. This allows a single
|
|
||||||
Swarm cluster to have two or more managers. One manager is elected as the
|
|
||||||
primary manager and all others operate as secondaries. In the event that the
|
|
||||||
primary manager fails, one of the secondaries is elected as the new primary, and
|
|
||||||
cluster operations continue gracefully. If you are deploying multiple Swarm
|
|
||||||
managers for high availability, you should consider spreading them across
|
|
||||||
multiple failure domains within your infrastructure.
|
|
||||||
|
|
||||||
### Consul (discovery backend) failures
|
|
||||||
|
|
||||||
The Swarm cluster that you have deployed has a single Consul container on a
|
|
||||||
single node performing the cluster discovery service. In this setup, if the
|
|
||||||
Consul container exits or the node fails, the application will continue to
|
|
||||||
operate in its current configuration. However, certain cluster management
|
|
||||||
operations will fail. These include registering new containers in the cluster
|
|
||||||
and making lookups against the cluster configuration.
|
|
||||||
|
|
||||||
If the failure is the `consul` container unexpectedly exiting, Docker will
|
|
||||||
automatically attempt to restart it. This is because the container was started
|
|
||||||
with the `--restart=unless-stopped` switch.
|
|
||||||
|
|
||||||
The `Consul`, `etcd`, and `Zookeeper` discovery service backends support various
|
|
||||||
options for high availability. These include Paxos/Raft quorums. You should
|
|
||||||
follow existing best practices for deploying HA configurations of your chosen
|
|
||||||
discover service backend. If you are deploying multiple discovery service
|
|
||||||
instances for high availability, you should consider spreading them across
|
|
||||||
multiple failure domains within your infrastructure.
|
|
||||||
|
|
||||||
If you operate your Swarm cluster with a single discovery backend service and
|
|
||||||
this service fails and is unrecoverable, you can start a new empty instance of
|
|
||||||
the discovery backend and the Swarm agents on each node in the cluster will
|
|
||||||
repopulate it.
|
|
||||||
|
|
||||||
|
|
||||||
#### Handling failures
|
|
||||||
|
|
||||||
There are many reasons why containers can fail. However, Swarm does not attempt
|
|
||||||
to restart failed containers.
|
|
||||||
|
|
||||||
One way to automatically restart failed containers is to explicitly start them
|
|
||||||
with the `--restart=unless-stopped` flag. This will tell the local Docker daemon
|
|
||||||
to attempt to restart the container if it unexpectedly exits. This will only
|
|
||||||
work in situations where the node hosting the container and it's Docker daemon
|
|
||||||
are still up. This cannot restart a container if the node hosting it has failed,
|
|
||||||
or if the Docker daemon itself has failed.
|
|
||||||
|
|
||||||
Another way is to have an external tool (external to the cluster) monitor the
|
|
||||||
state of your application, and make sure that certain service levels are
|
|
||||||
maintained. These service levels can include things like "have at least 10 web
|
|
||||||
server containers running". In this scenario, if the number of web containers
|
|
||||||
drops below 10, the tool will attempt to start more.
|
|
||||||
|
|
||||||
In our simple voting-app example, the front-end is scalable and serviced by a
|
|
||||||
load balancer. In the event that on the of the two web containers fails (or the
|
|
||||||
AWS instance that is hosting it), the load balancer will stop routing requests
|
|
||||||
to it and send all requests the surviving web container. This solution is highly
|
|
||||||
scalable meaning you can have up to *n* web containers behind the load balancer.
|
|
||||||
|
|
||||||
### Interlock load balancer failures
|
|
||||||
|
|
||||||
The environment that you have provisioned has a single
|
|
||||||
[interlock](https://github.com/ehazlett/interlock) load balancer container
|
|
||||||
running on a single node. In this setup, if the container exits or node fails,
|
|
||||||
the application will no longer be able to service incoming requests and the
|
|
||||||
application will be unavailable.
|
|
||||||
|
|
||||||
If the failure is the `interlock` container unexpectedly exiting, Docker will
|
|
||||||
automatically attempt to restart it. This is because the container was started
|
|
||||||
with the `--restart=unless-stopped` switch.
|
|
||||||
|
|
||||||
It is possible to build an HA Interlock load balancer configuration. One such
|
|
||||||
way is to have multiple Interlock containers on multiple nodes. You can then use
|
|
||||||
DNS round robin, or other technologies, to load balance across each Interlock
|
|
||||||
container. That way, if one Interlock container or node goes down, the others
|
|
||||||
will continue to service requests.
|
|
||||||
|
|
||||||
If you deploy multiple interlock load balancers, you should consider spreading
|
|
||||||
them across multiple failure domains within your infrastructure.
|
|
||||||
|
|
||||||
### Web (web-vote-app) failures
|
|
||||||
|
|
||||||
The environment that you have configured has two web-vote-app containers running
|
|
||||||
on two separate nodes. They operate behind an Interlock load balancer that
|
|
||||||
distributes incoming connections across both.
|
|
||||||
|
|
||||||
In the event that one of the web containers or nodes fails, the load balancer
|
|
||||||
will start directing all incoming requests to surviving instance. Once the
|
|
||||||
failed instance is back up, or a replacement is added, the load balancer will
|
|
||||||
add it to the configuration and start sending a portion of the incoming requests
|
|
||||||
to it.
|
|
||||||
|
|
||||||
For highest availability you should deploy the two frontend web services
|
|
||||||
(`frontend01` and `frontend02`) in different failure zones within your
|
|
||||||
infrastructure. You should also consider deploying more.
|
|
||||||
|
|
||||||
### Redis failures
|
|
||||||
|
|
||||||
If the a `redis` container fails, it's partnered `web-vote-app` container will
|
|
||||||
not function correctly. The best solution in this instance might be to configure
|
|
||||||
health monitoring that verifies the ability to write to each Redis instance. If
|
|
||||||
an unhealthy `redis` instance is encountered, remove the `web-vote-app` and
|
|
||||||
`redis` combination and attempt remedial actions.
|
|
||||||
|
|
||||||
### Worker (vote-worker) failures
|
|
||||||
|
|
||||||
If the worker container exits, or the node that is hosting it fails, the redis
|
|
||||||
containers will queue votes until the worker container comes back up. This
|
|
||||||
situation can prevail indefinitely, though a worker needs to come back at some
|
|
||||||
point and process the votes.
|
|
||||||
|
|
||||||
If the failure is the `worker01` container unexpectedly exiting, Docker will
|
|
||||||
automatically attempt to restart it. This is because the container was started
|
|
||||||
with the `--restart=unless-stopped` switch.
|
|
||||||
|
|
||||||
### Postgres failures
|
|
||||||
|
|
||||||
This application does not implement any for of HA or replication for Postgres.
|
|
||||||
Therefore losing the Postgres container would cause the application to fail and
|
|
||||||
potential lose or corrupt data. A better solution would be to implement some
|
|
||||||
form of Postgres HA or replication.
|
|
||||||
|
|
||||||
### Results-app failures
|
|
||||||
|
|
||||||
If the results-app container exits, you will not be able to browse to the
|
|
||||||
results of the poll until the container is back up and running. Results will
|
|
||||||
continue to be collected and counted, you will just not be able to view results
|
|
||||||
until the container is back up and running.
|
|
||||||
|
|
||||||
The results-app container was started with the `--restart=unless-stopped` flag
|
|
||||||
meaning that the Docker daemon will automatically attempt to restart it unless
|
|
||||||
it was administratively stopped.
|
|
||||||
|
|
||||||
### Infrastructure failures
|
|
||||||
|
|
||||||
There are many ways in which the infrastructure underpinning your applications
|
|
||||||
can fail. However, there are a few best practices that can be followed to help
|
|
||||||
mitigate and offset these failures.
|
|
||||||
|
|
||||||
One of these is to deploy infrastructure components over as many failure domains
|
|
||||||
as possible. On a service such as AWS, this often translates into balancing
|
|
||||||
infrastructure and services across multiple AWS Availability Zones (AZ) within a
|
|
||||||
Region.
|
|
||||||
|
|
||||||
To increase the availability of our Swarm cluster you could:
|
|
||||||
|
|
||||||
* Configure the Swarm manager for HA and deploy HA nodes in different AZs
|
|
||||||
* Configure the Consul discovery service for HA and deploy HA nodes in different AZs
|
|
||||||
* Deploy all scalable components of the application across multiple AZs
|
|
||||||
|
|
||||||
This configuration is shown in the diagram below.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
This will allow us to lose an entire AZ and still have our cluster and
|
|
||||||
application operate.
|
|
||||||
|
|
||||||
But it doesn't have to stop there. Some applications can be balanced across AWS
|
|
||||||
Regions. In our example we might deploy parts of our cluster and application in
|
|
||||||
the `us-west-1` Region and the rest in `us-east-1`. It's even becoming possible
|
|
||||||
to deploy services across cloud providers, or have balance services across
|
|
||||||
public cloud providers and your on premises date ceters!
|
|
||||||
|
|
||||||
The diagram below shows parts of the application and infrastructure deployed
|
|
||||||
across AWS and Microsoft Azure. But you could just as easily replace one of
|
|
||||||
those cloud providers with your own on premises data center. In these scenarios,
|
|
||||||
network latency and reliability is key to a smooth and workable solution.
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
## Related information
|
|
||||||
|
|
||||||
The application in this example could be deployed on Docker Universal Control Plane (UCP) which is currently in Beta release. To try the application on UCP in your environment, [request access to the UCP Beta release](https://www.docker.com/products/docker-universal-control-plane). Other useful documentation:
|
|
||||||
|
|
||||||
* [Plan for Swarm in production](plan-for-production.md)
|
|
||||||
* [Swarm and container networks](networking.md)
|
|
||||||
* [High availability in Docker Swarm](multi-manager-setup.md)
|
|
||||||
|
|
@ -0,0 +1,111 @@
|
||||||
|
<!--[metadata]>
|
||||||
|
+++
|
||||||
|
title = "Learn the application architecture"
|
||||||
|
description = "Try Swarm at scale"
|
||||||
|
keywords = ["docker, swarm, scale, voting, application, archiecture"]
|
||||||
|
[menu.main]
|
||||||
|
parent="scale_swarm"
|
||||||
|
weight=-99
|
||||||
|
+++
|
||||||
|
<![end-metadata]-->
|
||||||
|
|
||||||
|
# Learn the application architecture
|
||||||
|
|
||||||
|
On this page, you learn about the Swarm at scale example. Make sure you have
|
||||||
|
read through [the introduction](index.md) to get an idea of the skills and time
|
||||||
|
required first.
|
||||||
|
|
||||||
|
## Learn the example back story
|
||||||
|
|
||||||
|
Your company is a pet food company that has bought an commercial during the
|
||||||
|
Superbowl. The commercial drives viewers to a web survey that asks users to vote
|
||||||
|
– cats or dogs. You are developing the web survey.
|
||||||
|
|
||||||
|
Your survey must ensure that millions of people can vote concurrently without
|
||||||
|
your website becoming unavailable. You don't need real-time results, a company
|
||||||
|
press release announces the results. However, you do need confidence that every
|
||||||
|
vote is counted.
|
||||||
|
|
||||||
|
## Understand the application architecture
|
||||||
|
|
||||||
|
The voting application is a dockerized microservice application. It uses a
|
||||||
|
parallel web frontend that sends jobs to asynchronous background workers. The
|
||||||
|
application's design can accommodate arbitrarily large scale. The diagram below
|
||||||
|
shows the high level architecture of the application.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
The application is fully dockerized with all services running inside of
|
||||||
|
containers.
|
||||||
|
|
||||||
|
The frontend consists of an Interlock load balancer with *N* frontend web
|
||||||
|
servers and associated queues. The load balancer can handle an arbitrary number
|
||||||
|
of web containers behind it (`frontend01`- `frontendN`). The web containers run
|
||||||
|
a simple Python Flask application. Each web container accepts votes and queues
|
||||||
|
them to a Redis container on the same node. Each web container and Redis queue
|
||||||
|
pair operates independently.
|
||||||
|
|
||||||
|
The load balancer together with the independent pairs allows the entire
|
||||||
|
application to scale to an arbitrary size as needed to meet demand.
|
||||||
|
|
||||||
|
Behind the frontend is a worker tier which runs on separate nodes. This tier:
|
||||||
|
|
||||||
|
* scans the Redis containers
|
||||||
|
* dequeues votes
|
||||||
|
* deduplicates votes to prevent double voting
|
||||||
|
* commits the results to a Postgres container running on a separate node
|
||||||
|
|
||||||
|
Just like the front end, the worker tier can also scale arbitrarily. The worker
|
||||||
|
count and frontend count are independent from each other.
|
||||||
|
|
||||||
|
## Swarm Cluster Architecture
|
||||||
|
|
||||||
|
To support the application, the design calls for a Swarm cluster with a single
|
||||||
|
Swarm manager and four nodes as shown below.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
All four nodes in the cluster are running the Docker daemon, as is the Swarm
|
||||||
|
manager and the Interlock load balancer. The Swarm manager exists on a Docker
|
||||||
|
Engine host that is part of the cluster and is considered out of band for
|
||||||
|
the application. The Interlock load balancer could be placed inside of the
|
||||||
|
cluster, but for this demonstration it is not.
|
||||||
|
|
||||||
|
A container network is overlayed on top of the Swarm cluster using the container
|
||||||
|
overlay feature of Docker engine. The dockerized microservices are deployed to
|
||||||
|
this network. After completing the example and deploying your application, this
|
||||||
|
is what your environment should look like.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
As the previous diagram shows, each node in the cluster runs the following containers:
|
||||||
|
|
||||||
|
- `frontend01`:
|
||||||
|
- Container: Python flask web app (frontend01)
|
||||||
|
- Container: Redis (redis01)
|
||||||
|
- `frontend02`:
|
||||||
|
- Container: Python flask web app (frontend02)
|
||||||
|
- Container: Redis (redis02)
|
||||||
|
- `worker01`: vote worker app (worker01)
|
||||||
|
- `store`:
|
||||||
|
- Container: Postgres (pg)
|
||||||
|
- Container: results app (results-app)
|
||||||
|
|
||||||
|
After you deploy the application, you'll configure your local system so that you
|
||||||
|
can test the application from your local browser. In production, of course, this
|
||||||
|
step wouldn't be needed.
|
||||||
|
|
||||||
|
## The network infrastructure
|
||||||
|
|
||||||
|
The example assumes you are deploying the application to a Docker Swarm cluster
|
||||||
|
running on top of Amazon Web Services (AWS). AWS is an example only. There is
|
||||||
|
nothing about this application or deployment that requires it. You could deploy
|
||||||
|
the application to a Docker Swarm cluster running on; a different cloud provider
|
||||||
|
such as Microsoft Azure, on premises in your own physical data center, or in a
|
||||||
|
development environment on your laptop.
|
||||||
|
|
||||||
|
## Next step
|
||||||
|
|
||||||
|
Now that you understand the application architecture, you need to deploy a
|
||||||
|
network configuration that can support it. In the next step, you use AWS to
|
||||||
|
[deploy network infrastructure](02-deploy-infra.md) for use in this sample.
|
||||||
|
|
@ -0,0 +1,222 @@
|
||||||
|
<!--[metadata]>
|
||||||
|
+++
|
||||||
|
title = "Deploy network infrastructure"
|
||||||
|
description = "Try Swarm at scale"
|
||||||
|
keywords = ["docker, swarm, scale, voting, application, certificates"]
|
||||||
|
[menu.main]
|
||||||
|
parent="scale_swarm"
|
||||||
|
weight=-90
|
||||||
|
+++
|
||||||
|
<![end-metadata]-->
|
||||||
|
|
||||||
|
# Deploy your infrastructure
|
||||||
|
|
||||||
|
In this step, you create an AWS Virtual Private Cloud (VPC) to run your
|
||||||
|
application stack on. Before you continue, make sure you have taken the time to
|
||||||
|
[learn the application architecture](01-about.md).
|
||||||
|
|
||||||
|
This example uses AWS but the AWS provider is only one example of an
|
||||||
|
infrastructure you can use. You can create the environment design on whatever
|
||||||
|
infrastructure you wish. For example, you could place the application on another
|
||||||
|
public cloud platform such as Azure or DigitalOcean, on premises in your data
|
||||||
|
center, or even in in a test environment on your laptop.
|
||||||
|
|
||||||
|
>**Note**: If you are not deploying to AWS, or are not using the CloudFormation
|
||||||
|
template used in the instructions below, make sure your Docker hosts are running
|
||||||
|
a 3.16 or higher kernel. This kernel is required by Docker's container
|
||||||
|
networking feature.
|
||||||
|
|
||||||
|
## Overview of the deployment process
|
||||||
|
|
||||||
|
To deploy on an AWS infrastructure, you first build a VPC and then apply apply
|
||||||
|
the [CloudFormation template](https://github.com/docker/swarm-microservice-demo-v1/blob/master/AWS/cloudformation.json) prepared for you. The template describes the hosts in the example's stack. While you
|
||||||
|
could create the entire VPC and all instances via a CloudFormation template,
|
||||||
|
splitting the deployment into two steps lets you use the CloudFormation template
|
||||||
|
to build the stack on an *existing VPCs*.
|
||||||
|
|
||||||
|
The diagram below shows the VPC infrastructure required to run the
|
||||||
|
CloudFormation template.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
The configuration is a single VPC with a single public subnet. The VPC
|
||||||
|
deployment relies on a <a
|
||||||
|
href="https://raw.githubusercontent.com/docker/swarm-microservice-demo-v1/master/AWS/cloudformation.json">cloudformation.json
|
||||||
|
template</a> which specifies in the `us-west-1` Region (N. California) or
|
||||||
|
`us-west-2` (Oregon). The ability to create instances one of these regions is
|
||||||
|
**required** for this particular CloudFormation template to work. If you want to
|
||||||
|
use a different region, edit the template before the import step.
|
||||||
|
|
||||||
|
The VPC network address space is `192.168.0.0/16` and single 24-bit public
|
||||||
|
subnet is carved out as 192.168.33.0/24. The subnet must be configured with a
|
||||||
|
default route to the internet via the VPC's internet gateway. All six EC2
|
||||||
|
instances are deployed into this public subnet.
|
||||||
|
|
||||||
|
Once the VPC is created, you deploy the EC2 instances using the
|
||||||
|
CloudFormation template located
|
||||||
|
[in the `docker/swarm-microservice-demo-v1` repository](https://github.com/docker/swarm-microservice-demo-v1/blob/master/AWS/cloudformation.json).
|
||||||
|
|
||||||
|
## Prerequisites
|
||||||
|
|
||||||
|
You'll need to have an Amazon AWS account. This account can be personal or
|
||||||
|
through a corporate instance. The account must be able to deploy EC2 instances
|
||||||
|
in the `us-west-1` region (N. California).
|
||||||
|
|
||||||
|
Before starting through this procedure, make sure you have an existing EC2 key
|
||||||
|
pair in the `us-west-1` region and that you have download its `.pem` file. If
|
||||||
|
you aren't sure, login into AWS. Then, <a
|
||||||
|
href="http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html"
|
||||||
|
target="_blank">follow the AWS documentation</a> to ensure you have the key pair
|
||||||
|
and have downloaded the `.pem` file.
|
||||||
|
|
||||||
|
Git clone the <a href="https://github.com/docker/swarm-microservice-demo-v1"
|
||||||
|
target="_blank">example application's GitHub repo</a> to your local machine. If
|
||||||
|
you prefer, you can instead [download a `zip`
|
||||||
|
file](https://github.com/docker/swarm-microservice-demo-v1/archive/master.zip)
|
||||||
|
and unzip the code in your local environment.
|
||||||
|
|
||||||
|
## Step 1. Build and configure the VPC
|
||||||
|
|
||||||
|
This step shows you using the VPC wizard on Amazon. If you prefer to build the
|
||||||
|
VPC manually, configure your VPC with the following values:
|
||||||
|
|
||||||
|
| Field | Value |
|
||||||
|
|---------------------------|------------------------------------------------------------------------------------------------|
|
||||||
|
| **VPC Network (CIDR)** | 192.168.0.0/16 |
|
||||||
|
| **VPC Name** | swarm-scale |
|
||||||
|
| **Subnet network (CIDR)** | 192.168.33.0/24 |
|
||||||
|
| **Availability Zone** | N. California (us-west-1a or b) |
|
||||||
|
| **Subnet name** | publicSwarm |
|
||||||
|
| **DNS resolution** | Yes |
|
||||||
|
| **Subnet type** | Public (with route to the internet) |
|
||||||
|
| **Availability Zone** | Any |
|
||||||
|
| **Auto-assign public IP** | Yes |
|
||||||
|
| **Router** | A single router with a route for *local* traffic and default route for traffic to the internet |
|
||||||
|
| **Internet gateway** | A single internet gateway used as default route for the subnet's routing table |
|
||||||
|
|
||||||
|
To build the VPC, with the wizard.
|
||||||
|
|
||||||
|
1. Go to the VPC dashboard.
|
||||||
|
|
||||||
|
2. Choose **Start VPC Wizard**.
|
||||||
|
|
||||||
|
3. Make sure **VPC with a Single Public Subnet** is selected.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
4. Click **Select**.
|
||||||
|
|
||||||
|
The browser displays the **Step 2: VPC with a Single Public Subnet** dialog.
|
||||||
|
|
||||||
|
5. Complete the dialog as follows:
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
6. Click **Create VPC**.
|
||||||
|
|
||||||
|
AWS works to build the VPC and then presents you with the **VPC Successfully
|
||||||
|
Created** page.
|
||||||
|
|
||||||
|
7. Click **OK**.
|
||||||
|
|
||||||
|
8. Choose **Subnets** from the **VPC Dashboard** menu.
|
||||||
|
|
||||||
|
9. Locate your `publicSwarm` subnet.
|
||||||
|
|
||||||
|
10. Choose **Subnet Actions > Modify Auto-Assign Public IP**.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
11. Select **Enable auto-assign Public IP** and click **Save**.
|
||||||
|
|
||||||
|
In the next step, you configure the remaining AWS settings by using a
|
||||||
|
CloudFormation template.
|
||||||
|
|
||||||
|
## Step 2. Build the network stack
|
||||||
|
|
||||||
|
In this step, you use CloudFormation template to build a stack on AWS. Before
|
||||||
|
you begin, make sure you have the prerequisites:
|
||||||
|
|
||||||
|
- access to a private key pair associated with your AWS account.
|
||||||
|
- a clone or download of the <a
|
||||||
|
href="https://github.com/docker/swarm-microservice-demo-v1" target="_blank">the
|
||||||
|
example code</a> on your local machine.
|
||||||
|
|
||||||
|
Then, do the following:
|
||||||
|
|
||||||
|
1. Go to the AWS console and choose **CloudFormation**.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
2. Click **Create Stack**.
|
||||||
|
|
||||||
|
3. Under **Choose a template** click the **Choose file** button.
|
||||||
|
|
||||||
|
4. Browse to the download sample code and choose the the `swarm-microservice-demo-v1/AWS/cloudformation.json` CloudFormation template.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
5. Click **Next**.
|
||||||
|
|
||||||
|
The system pre-populates most of the **Specify Details** dialog from the template.
|
||||||
|
|
||||||
|
6. Name the stack `VotingAppStack`.
|
||||||
|
|
||||||
|
You can name the stack something else if you want just make sure it is meaningful.
|
||||||
|
|
||||||
|
7. Select your key pair from the **KeyName** dropdown.
|
||||||
|
|
||||||
|
8. Select the `publicSwarm` for the **Subnetid** dropdown menu.
|
||||||
|
|
||||||
|
9. Select `swarm-scale` from the **Vpcid** dropdown menu.
|
||||||
|
|
||||||
|
10. Click **Next** twice to reach the **Review** page.
|
||||||
|
|
||||||
|
11. Check the values.
|
||||||
|
|
||||||
|
The **Template URL**,**SubnetId** and **VpcId** are always unique, so yours
|
||||||
|
will not match, but otherwise you should see the following:
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
12. Click **Create**.
|
||||||
|
|
||||||
|
AWS displays the progress of your stack being created
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
## Step 3. Check your deployment
|
||||||
|
|
||||||
|
When completed, the CloudFormation populates your VPC with six EC2 instances.
|
||||||
|
|
||||||
|
| Instance | Size | Private IP Address |
|
||||||
|
|--------------|-----------|--------------------|
|
||||||
|
| `frontend01` | t2.micro | 192.168.33.20 |
|
||||||
|
| `frontend02` | t2.micro | 192.168.33.21 |
|
||||||
|
| `interlock` | t2.micro | 192.168.33.12 |
|
||||||
|
| `manager` | t2.micro | 192.168.33.11 |
|
||||||
|
| `store` | m3.medium | 192.168.33.250 |
|
||||||
|
| `worker01` | t2.micro | 192.168.33.200 |
|
||||||
|
|
||||||
|
Navigate to the EC2 dashboard to view them running.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
The underlying AWS infrastructure has this configuration.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
All instances are based on the `ami-56f59e36` AMI. This is an Ubuntu 14.04 image
|
||||||
|
with a 3.13 kernel and 1.10.2 version of the Docker Engine installed. Each Engine
|
||||||
|
daemon was pre-configured via the `/etc/default/docker` file using the following
|
||||||
|
`DOCKER_OPTS` values.
|
||||||
|
|
||||||
|
```
|
||||||
|
--cluster-store=consul://192.168.33.11:8500 --cluster-advertise=eth0:2375 -H=tcp://0.0.0.0:2375 -H=unix:///var/run/docker.sock
|
||||||
|
```
|
||||||
|
|
||||||
|
## Next step
|
||||||
|
|
||||||
|
At this point your infrastructure stack is created successfully. You are ready
|
||||||
|
to progress to the next step and [build the Swarm
|
||||||
|
cluster](03-create-cluster.md).
|
||||||
|
|
@ -0,0 +1,332 @@
|
||||||
|
<!--[metadata]>
|
||||||
|
+++
|
||||||
|
title = "Setup cluster resources"
|
||||||
|
description = "Try Swarm at scale"
|
||||||
|
keywords = ["docker, swarm, scale, voting, application, certificates"]
|
||||||
|
[menu.main]
|
||||||
|
parent="scale_swarm"
|
||||||
|
weight=-89
|
||||||
|
+++
|
||||||
|
<![end-metadata]-->
|
||||||
|
|
||||||
|
# Setup cluster resources
|
||||||
|
|
||||||
|
Now that [your underlying network infrastructure is built](02-deploy-infra.md),
|
||||||
|
you can deploye and configure the Swarm cluster. A host in a Swarm cluster is
|
||||||
|
called a *node*. So, these instructions refer to each AWS EC2 instances as a
|
||||||
|
node and refers to each node by the **Name** it appears as in your EC2
|
||||||
|
Dashboard**.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
The steps on this page construct a Swarm cluster by:
|
||||||
|
|
||||||
|
* using Consul as the discovery backend
|
||||||
|
* join the `frontend`, `worker`
|
||||||
|
* `store` EC2 instances to the cluster
|
||||||
|
* use the `spread` scheduling strategy
|
||||||
|
|
||||||
|
You'll perform all the configuration steps from the Swarm manager node. The
|
||||||
|
manager node has access to all the instances in the cluster.
|
||||||
|
|
||||||
|
## Step 1: Construct the cluster
|
||||||
|
|
||||||
|
In this step, you create a Consul container for use as the Swarm discovery
|
||||||
|
service. The Consul backend is also used as the K/V store for the container
|
||||||
|
network that you overlay on the Swarm cluster in a later step. After you launch
|
||||||
|
the Consul container, you launch a Swarm manager container.
|
||||||
|
|
||||||
|
1. Select the `manager` node and click **Connect** to display the `ssh` command you'll need.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
2. Open a terminal on your `manager` node with the `ssh` command.
|
||||||
|
|
||||||
|
3. Start a Consul container that listens on TCP port `8500`.
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped -d -p 8500:8500 -h consul progrium/consul -server -bootstrap
|
||||||
|
Unable to find image 'progrium/consul:latest' locally
|
||||||
|
latest: Pulling from progrium/consul
|
||||||
|
3b4d28ce80e4: Pull complete
|
||||||
|
...<output snip>...
|
||||||
|
d9125e9e799b: Pull complete
|
||||||
|
Digest: sha256:8cc8023462905929df9a79ff67ee435a36848ce7a10f18d6d0faba9306b97274
|
||||||
|
Status: Downloaded newer image for progrium/consul:latest
|
||||||
|
6136de6829916430ee911cc14e3f067624fcf6d3041d404930f6dbcbf5399f7d
|
||||||
|
|
||||||
|
4. Confirm the container is running.
|
||||||
|
|
||||||
|
$ docker ps
|
||||||
|
IMAGE COMMAND CREATED STATUS PORTS NAMES
|
||||||
|
6136de682991 progrium/consul "/bin/start -server -" About a minute ago Up About a minute 53/tcp, 53/udp, 8300-8302/tcp, 8400/tcp, 0.0.0.0:8500->8500/tcp, 8301-8302/udp goofy_jepsen
|
||||||
|
|
||||||
|
5. Start a Swarm manager container.
|
||||||
|
|
||||||
|
This command maps port `3375` on the `manager` node to port `2375` in the
|
||||||
|
Swarm manager container.
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped -d -p 3375:2375 swarm manage consul://192.168.33.11:8500/
|
||||||
|
Unable to find image 'swarm:latest' locally
|
||||||
|
latest: Pulling from library/swarm
|
||||||
|
887115b43fc0: Pull complete
|
||||||
|
...<output snip>...
|
||||||
|
f3f134eb6413: Pull complete
|
||||||
|
Digest: sha256:51a8eba9502f1f89eef83e10b9f457cfc67193efc3edf88b45b1e910dc48c906
|
||||||
|
Status: Downloaded newer image for swarm:latest
|
||||||
|
f5f093aa9679410bee74b7f3833fb01a3610b184a530da7585c990274bd65e7e
|
||||||
|
|
||||||
|
The Swarm manager container is the heart of your Swarm cluster. It is
|
||||||
|
responsible for receiving all Docker commands sent to the cluster, and for
|
||||||
|
scheduling resources against the cluster. In a real-world production
|
||||||
|
deployment you would configure additional replica Swarm managers as
|
||||||
|
secondaries for high availability (HA).
|
||||||
|
|
||||||
|
6. Get information about your Docker installation.
|
||||||
|
|
||||||
|
$ docker info
|
||||||
|
Containers: 2
|
||||||
|
Images: 26
|
||||||
|
Server Version: 1.9.1
|
||||||
|
Storage Driver: aufs
|
||||||
|
Root Dir: /var/lib/docker/aufs
|
||||||
|
Backing Filesystem: extfs
|
||||||
|
Dirs: 30
|
||||||
|
Dirperm1 Supported: true
|
||||||
|
Execution Driver: native-0.2
|
||||||
|
Logging Driver: json-file
|
||||||
|
Kernel Version: 3.16.0-57-generic
|
||||||
|
Operating System: Ubuntu 14.04.3 LTS
|
||||||
|
CPUs: 1
|
||||||
|
Total Memory: 992.2 MiB
|
||||||
|
Name: manager
|
||||||
|
ID: IISM:V4KJ:VXCT:ONN3:MFIJ:2ZLD:VI6I:UYB3:FJZ4:3O7J:FHKA:P3XS
|
||||||
|
WARNING: No swap limit support
|
||||||
|
Cluster store: consul://192.168.33.11:8500
|
||||||
|
Cluster advertise: 192.168.33.11:2375
|
||||||
|
|
||||||
|
The command information returns the information about the Engine and its
|
||||||
|
daemon.
|
||||||
|
|
||||||
|
7. Confirm that you have the `consul` and `swarm manage` containers running.
|
||||||
|
|
||||||
|
$ docker ps
|
||||||
|
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
|
||||||
|
f5f093aa9679 swarm "/swarm manage consul" About a minute ago Up About a minute 0.0.0.0:3375->2375/tcp sad_goldstine
|
||||||
|
6136de682991 progrium/consul "/bin/start -server -" 9 minutes ago Up 9 minutes 53/tcp, 53/udp, 8300-8302/tcp, 8301-8302/udp, 8400/tcp, 0.0.0.0:8500->8500/tcp goofy_jepsen
|
||||||
|
|
||||||
|
7. Set the `DOCKER_HOST` environment variable.
|
||||||
|
|
||||||
|
This ensures that the default endpoint for Docker Engine CLI commands is the
|
||||||
|
Engine daemon running on the `manager` node.
|
||||||
|
|
||||||
|
$ export DOCKER_HOST="tcp://192.168.33.11:3375"
|
||||||
|
|
||||||
|
8. Now that your terminal environment is set to the Swarm port, rerun the
|
||||||
|
`docker info` command.
|
||||||
|
|
||||||
|
$ docker info
|
||||||
|
Containers: 0
|
||||||
|
Images: 0
|
||||||
|
Role: primary
|
||||||
|
Strategy: spread
|
||||||
|
Filters: health, port, dependency, affinity, constraint
|
||||||
|
Nodes: 0
|
||||||
|
Kernel Version: 3.16.0-57-generic
|
||||||
|
Operating System: linux
|
||||||
|
CPUs: 0
|
||||||
|
Total Memory: 0 B
|
||||||
|
Name: f5f093aa9679
|
||||||
|
|
||||||
|
The command is acting on the Swarm port, so it returns information about the
|
||||||
|
entire cluster. You have a manager and no nodes.
|
||||||
|
|
||||||
|
9. While still on the `master` node, join each node one-by-one to the cluster.
|
||||||
|
|
||||||
|
You can run these commands to join each node from the `manager` node command
|
||||||
|
line. The `-H` flag with the `docker` command specifies a node IP address
|
||||||
|
and the Engine port. Each command goes over the cluster to the node's Docker
|
||||||
|
daemon. The `join` command joins a node to the cluster and registers it with
|
||||||
|
the Consul discovery service.
|
||||||
|
|
||||||
|
**frontend01**:
|
||||||
|
|
||||||
|
docker -H=tcp://192.168.33.20:2375 run -d swarm join --advertise=192.168.33.20:2375 consul://192.168.33.11:8500/
|
||||||
|
|
||||||
|
**frontend02**:
|
||||||
|
|
||||||
|
docker -H=tcp://192.168.33.21:2375 run -d swarm join --advertise=192.168.33.21:2375 consul://192.168.33.11:8500/
|
||||||
|
|
||||||
|
**worker01**:
|
||||||
|
|
||||||
|
docker -H=tcp://192.168.33.200:2375 run -d swarm join --advertise=192.168.33.200:2375 consul://192.168.33.11:8500/
|
||||||
|
|
||||||
|
**store**:
|
||||||
|
|
||||||
|
docker -H=tcp://192.168.33.250:2375 run -d swarm join --advertise=192.168.33.250:2375 consul://192.168.33.11:8500/
|
||||||
|
|
||||||
|
|
||||||
|
9. Run the `docker info` command again to view your cluster with all its nodes.
|
||||||
|
|
||||||
|
$ docker info
|
||||||
|
Containers: 4
|
||||||
|
Images: 4
|
||||||
|
Role: primary
|
||||||
|
Strategy: spread
|
||||||
|
Filters: health, port, dependency, affinity, constraint
|
||||||
|
Nodes: 4
|
||||||
|
frontend01: 192.168.33.20:2375
|
||||||
|
└ Status: Healthy
|
||||||
|
└ Containers: 1
|
||||||
|
└ Reserved CPUs: 0 / 1
|
||||||
|
└ Reserved Memory: 0 B / 1.017 GiB
|
||||||
|
└ Labels: executiondriver=native-0.2, kernelversion=3.16.0-57-generic, operatingsystem=Ubuntu 14.04.3 LTS, storagedriver=aufs
|
||||||
|
└ Error: (none)
|
||||||
|
└ UpdatedAt: 2016-02-14T19:02:53Z
|
||||||
|
frontend02: 192.168.33.21:2375
|
||||||
|
└ Status: Healthy
|
||||||
|
└ Containers: 1
|
||||||
|
└ Reserved CPUs: 0 / 1
|
||||||
|
└ Reserved Memory: 0 B / 1.017 GiB
|
||||||
|
└ Labels: executiondriver=native-0.2, kernelversion=3.16.0-57-generic, operatingsystem=Ubuntu 14.04.3 LTS, storagedriver=aufs
|
||||||
|
└ Error: (none)
|
||||||
|
└ UpdatedAt: 2016-02-14T19:02:58Z
|
||||||
|
store: 192.168.33.250:2375
|
||||||
|
└ Status: Healthy
|
||||||
|
└ Containers: 1
|
||||||
|
└ Reserved CPUs: 0 / 1
|
||||||
|
└ Reserved Memory: 0 B / 3.86 GiB
|
||||||
|
└ Labels: executiondriver=native-0.2, kernelversion=3.16.0-57-generic, operatingsystem=Ubuntu 14.04.3 LTS, storagedriver=aufs
|
||||||
|
└ Error: (none)
|
||||||
|
└ UpdatedAt: 2016-02-14T19:02:58Z
|
||||||
|
worker01: 192.168.33.200:2375
|
||||||
|
└ Status: Healthy
|
||||||
|
└ Containers: 1
|
||||||
|
└ Reserved CPUs: 0 / 1
|
||||||
|
└ Reserved Memory: 0 B / 1.017 GiB
|
||||||
|
└ Labels: executiondriver=native-0.2, kernelversion=3.16.0-57-generic, operatingsystem=Ubuntu 14.04.3 LTS, storagedriver=aufs
|
||||||
|
└ Error: (none)
|
||||||
|
└ UpdatedAt: 2016-02-14T19:03:21Z
|
||||||
|
Kernel Version: 3.16.0-57-generic
|
||||||
|
Operating System: linux
|
||||||
|
CPUs: 4
|
||||||
|
Total Memory: 6.912 GiB
|
||||||
|
Name: f5f093aa9679
|
||||||
|
|
||||||
|
### Step 2: Review your work
|
||||||
|
|
||||||
|
The diagram below shows the Swarm cluster that you created.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
The `manager` node is running two containers: `consul` and `swarm`. The `consul`
|
||||||
|
container is providing the Swarm discovery service. This is where nodes and
|
||||||
|
services register themselves and discover each other. The `swarm` container is
|
||||||
|
running the `swarm manage` process which makes it act as the cluster manager.
|
||||||
|
The manager is responsible for accepting Docker commands issued against the
|
||||||
|
cluster and scheduling resources on the cluster.
|
||||||
|
|
||||||
|
You mapped port 3375 on the `manager` node to port 2375 inside the `swarm`
|
||||||
|
container. As a result, Docker clients (for example the CLI) wishing to issue
|
||||||
|
commands against the cluster must send them to the `manager` node on port
|
||||||
|
3375. The `swarm` container then executes those commands against the relevant
|
||||||
|
node(s) in the cluster over port 2375.
|
||||||
|
|
||||||
|
Now that you have your Swarm cluster configured, you'll overlay the container
|
||||||
|
network that the application containers will be part of.
|
||||||
|
|
||||||
|
### Step 2: Overlay a container network
|
||||||
|
|
||||||
|
All containers that are part of the voting application should belong to a
|
||||||
|
container network called `mynet`. Container networking is a Docker Engine
|
||||||
|
feature. The` mynet` network is a overlay network type that runs on top of the
|
||||||
|
communication network.
|
||||||
|
|
||||||
|
A container network can span multiple hosts on multiple networks. As a result,
|
||||||
|
the `mynet` container network allows all the voting application containers to
|
||||||
|
easily communicate irrespective of the underlying communication network that
|
||||||
|
each node is on.
|
||||||
|
|
||||||
|
You can create the network and join the containers from any node in your VPC
|
||||||
|
that is running Docker Engine. However, best practice when using Docker Swarm is
|
||||||
|
to execute commands from the `manager` node, as this is where all management
|
||||||
|
tasks happen.
|
||||||
|
|
||||||
|
1. If you haven't already, `ssh` into a terminal on your `manager` node.
|
||||||
|
|
||||||
|
2. Get information about the network running on just the `manager` node.
|
||||||
|
|
||||||
|
You do this by passing the `-H` flag to restrict the Engine CLI to just
|
||||||
|
the manager node.
|
||||||
|
|
||||||
|
$ docker -H=tcp://192.168.33.11:2375 network ls
|
||||||
|
NETWORK ID NAME DRIVER
|
||||||
|
d01e8f0303a9 none null
|
||||||
|
bab7a9c42a23 host host
|
||||||
|
12fd2a115d85 bridge bridge
|
||||||
|
|
||||||
|
3. Now, run the same command to get cluster information.
|
||||||
|
|
||||||
|
Provided you set `export DOCKER_HOST="tcp://192.168.33.11:3375"``, the
|
||||||
|
command directs to the Swarm port and returns information from each node in
|
||||||
|
the cluster.
|
||||||
|
|
||||||
|
$ docker network ls
|
||||||
|
NETWORK ID NAME DRIVER
|
||||||
|
82ce2adce6a7 store/bridge bridge
|
||||||
|
c3ca43d2622d store/host host
|
||||||
|
d126c4b1e092 frontend01/host host
|
||||||
|
6ea89a1a5b6a frontend01/bridge bridge
|
||||||
|
d3ddb830d7f5 frontend02/host host
|
||||||
|
44f238353c14 frontend02/bridge bridge
|
||||||
|
c500baec447e frontend02/none null
|
||||||
|
77897352f138 store/none null
|
||||||
|
8060bd575770 frontend01/none null
|
||||||
|
429e4b8c2c8d worker01/bridge bridge
|
||||||
|
57c5001aca83 worker01/none null
|
||||||
|
2101103b8494 worker01/host host
|
||||||
|
|
||||||
|
4. Create the overlay network with the `docker network` command
|
||||||
|
|
||||||
|
$ docker network create --driver overlay mynet
|
||||||
|
|
||||||
|
5. Repeat the two network commands again to see how the network list has changed.
|
||||||
|
|
||||||
|
docker network ls
|
||||||
|
docker -H=tcp://192.168.33.11:2375 network ls
|
||||||
|
|
||||||
|
As all Swarm nodes in your environment are configured to use the Consul
|
||||||
|
discovery service at `consul://192.168.33.11:8500`, they all should see the
|
||||||
|
new overlay network. Verify this with the next step.
|
||||||
|
|
||||||
|
3. Try running a network command on an individual node, for example to run it on
|
||||||
|
the `frontend01` node:
|
||||||
|
|
||||||
|
docker -H=tcp://192.168.33.20:2375 network ls
|
||||||
|
|
||||||
|
You should see an entry for the `mynet` network using the `overlay` driver
|
||||||
|
as shown above. You would get the same output if your ran the command from
|
||||||
|
node's command line.
|
||||||
|
|
||||||
|
## Step 4: Review your work
|
||||||
|
|
||||||
|
The diagram below shows the complete cluster configuration including the overlay
|
||||||
|
container network, `mynet`. The `mynet` is shown as red and is available to all
|
||||||
|
Docker hosts using the Consul discovery backend. Later in the procedure you will
|
||||||
|
connect containers to this network.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
The `swarm` and `consul` containers on the `manager` node are not attached to
|
||||||
|
the `mynet` overlay network. These containers are running on `manager` nodes
|
||||||
|
default bridge network. To verify this try using these two commands:
|
||||||
|
|
||||||
|
docker -H=tcp://192.168.33.11:2375 network inspect bridge
|
||||||
|
docker -H=tcp://192.168.33.11:2375 network inspect mynet
|
||||||
|
|
||||||
|
You should find two containers running on the `manager` node's `bridge` network
|
||||||
|
but nothing yet on the `mynet` network.
|
||||||
|
|
||||||
|
## Next Step
|
||||||
|
|
||||||
|
Your Swarm cluster is now built and you are ready to [build and run the voting
|
||||||
|
application](04-deploy-app.md) on it.
|
||||||
|
|
@ -0,0 +1,306 @@
|
||||||
|
<!--[metadata]>
|
||||||
|
+++
|
||||||
|
title = "Deploy the application"
|
||||||
|
description = "Try Swarm at scale"
|
||||||
|
keywords = ["docker, swarm, scale, voting, application, certificates"]
|
||||||
|
[menu.main]
|
||||||
|
parent="scale_swarm"
|
||||||
|
weight=-80
|
||||||
|
+++
|
||||||
|
<![end-metadata]-->
|
||||||
|
|
||||||
|
# Deploy the application
|
||||||
|
|
||||||
|
You've [built a Swarm cluster](03-create-cluster.md) so now you are ready to
|
||||||
|
build and deploy the voting application itself.
|
||||||
|
|
||||||
|
|
||||||
|
## Step 1: Learn about the images
|
||||||
|
|
||||||
|
Some of the application's containers are launched form existing images pulled
|
||||||
|
directly from Docker Hub. Other containers are launched from custom images you
|
||||||
|
must build. The list below shows which containers use custom images and which do
|
||||||
|
not:
|
||||||
|
|
||||||
|
- Load balancer container: stock image (`ehazlett/interlock`)
|
||||||
|
- Redis containers: stock image (official `redis` image)
|
||||||
|
- Postgres (PostgreSQL) containers: stock image (official `postgres` image)
|
||||||
|
- Web containers: custom built image
|
||||||
|
- Worker containers: custom built image
|
||||||
|
- Results containers: custom built image
|
||||||
|
|
||||||
|
All custom built images are built using Dockerfile's pulled from the
|
||||||
|
[example application's public GitHub
|
||||||
|
repository](https://github.com/docker/swarm-microservice-demo-v1).
|
||||||
|
|
||||||
|
1. If you haven't already, `ssh` into the Swarm `manager` node.
|
||||||
|
|
||||||
|
2. Clone the [application's GitHub repo](https://github.com/docker/swarm-microservice-demo-v1)
|
||||||
|
|
||||||
|
$ git clone https://github.com/docker/swarm-microservice-demo-v1
|
||||||
|
sudo: unable to resolve host master
|
||||||
|
Cloning into 'swarm-microservice-demo-v1'...
|
||||||
|
remote: Counting objects: 304, done.
|
||||||
|
remote: Compressing objects: 100% (17/17), done.
|
||||||
|
remote: Total 304 (delta 5), reused 0 (delta 0), pack-reused 287
|
||||||
|
Receiving objects: 100% (304/304), 2.24 MiB | 2.88 MiB/s, done.
|
||||||
|
Resolving deltas: 100% (132/132), done.
|
||||||
|
Checking connectivity... done.
|
||||||
|
|
||||||
|
This command creates a new directory structure inside of your working
|
||||||
|
directory. The new directory contains all of the files and folders required
|
||||||
|
to build the voting application images.
|
||||||
|
|
||||||
|
The `AWS` directory contains the `cloudformation.json` file used to deploy
|
||||||
|
the EC2 instances. The `Vagrant` directory contains files and instructions
|
||||||
|
required to deploy the application using Vagrant. The `results-app`,
|
||||||
|
`vote-worker`, and `web-vote-app` directories contain the Dockerfiles and
|
||||||
|
other files required to build the custom images for those particular
|
||||||
|
components of the application.
|
||||||
|
|
||||||
|
3. Change directory into the `swarm-microservice-demo-v1/web-vote-app` directory.
|
||||||
|
|
||||||
|
$ cd swarm-microservice-demo-v1/web-vote-app/
|
||||||
|
|
||||||
|
4. View the Dockerfile contents.
|
||||||
|
|
||||||
|
$ cat Dockerfile
|
||||||
|
# Using official python runtime base image
|
||||||
|
FROM python:2.7
|
||||||
|
# Set the application directory
|
||||||
|
WORKDIR /app
|
||||||
|
# Install our requirements.txt
|
||||||
|
ADD requirements.txt /app/requirements.txt
|
||||||
|
RUN pip install -r requirements.txt
|
||||||
|
# Copy our code from the current folder to /app inside the container
|
||||||
|
ADD . /app
|
||||||
|
# Make port 80 available for links and/or publish
|
||||||
|
EXPOSE 80
|
||||||
|
# Define our command to be run when launching the container
|
||||||
|
CMD ["python", "app.py"]
|
||||||
|
|
||||||
|
As you can see, the image is based on the official `Python:2.7` tagged
|
||||||
|
image, adds a requirements file into the `/app` directory, installs
|
||||||
|
requirements, copies files from the build context into the container,
|
||||||
|
exposes port `80` and tells the container which command to run.
|
||||||
|
|
||||||
|
5. Spend time investigating the other parts of the application by viewing the `results-app/Dockefile` and the `vote-worker/Dockerfile` in the application.
|
||||||
|
|
||||||
|
## Step 2. Build custom images
|
||||||
|
|
||||||
|
1. If you haven't already, `ssh` into the Swarm `manager` node.
|
||||||
|
|
||||||
|
2. Make sure you have DOCKER_HOST set
|
||||||
|
|
||||||
|
$ export DOCKER_HOST="tcp://192.168.33.11:3375"
|
||||||
|
|
||||||
|
3. Change to the root of your `swarm-microservice-demo-v1` clone.
|
||||||
|
|
||||||
|
4. Build the `web-votes-app` image both the front end nodes.
|
||||||
|
|
||||||
|
**frontend01**:
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.20:2375 build -t web-vote-app ./web-vote-app
|
||||||
|
|
||||||
|
**frontend02**:
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.21:2375 build -t web-vote-app ./web-vote-app
|
||||||
|
|
||||||
|
These commands build the `web-vote-app` image on the `frontend01` and
|
||||||
|
`frontend02` nodes. To accomplish the operation, each command copies the
|
||||||
|
contents of the `swarm-microservice-demo-v1/web-vote-app` sub-directory from the
|
||||||
|
`manager` node to each frontend node. The command then instructs the
|
||||||
|
Docker daemon on each frontend node to build the image and store it locally.
|
||||||
|
|
||||||
|
You'll notice this example uses a `-H` flag to pull an image to specific
|
||||||
|
host. This is to help you conceptualize the architecture for this sample. In
|
||||||
|
a production deployment, you'd omit this option and rely on the Swarm
|
||||||
|
manager to distribute the image. The manager would pull the image to every
|
||||||
|
node; so that any node can step in to run the image as needed.
|
||||||
|
|
||||||
|
It may take a minute or so for each image to build. Wait for the builds to finish.
|
||||||
|
|
||||||
|
5. Build `vote-worker` image on the `worker01` node
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.200:2375 build -t vote-worker ./vote-worker
|
||||||
|
|
||||||
|
It may take a minute or so for the image to build. Wait for the build to
|
||||||
|
finish.
|
||||||
|
|
||||||
|
5. Build the `results-app` on the `store` node
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.250:2375 build -t results-app ./results-app
|
||||||
|
|
||||||
|
Each of the *custom images* required by the application is now built and stored
|
||||||
|
locally on the nodes that will use them.
|
||||||
|
|
||||||
|
## Step 3. Pull images from Docker Hub
|
||||||
|
|
||||||
|
For performance reasons, it is always better to pull any required Docker Hub
|
||||||
|
images locally on each instance that needs them. This ensures that containers
|
||||||
|
based on those images can start quickly.
|
||||||
|
|
||||||
|
1. Log into the Swarm `manager` node.
|
||||||
|
|
||||||
|
2. Pull the `redis` image to your frontend nodes.
|
||||||
|
|
||||||
|
**frontend01**:
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.20:2375 pull redis
|
||||||
|
|
||||||
|
**frontend02**:
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.21:2375 pull redis
|
||||||
|
|
||||||
|
2. Pull the `postgres` image to the `store` node
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.250:2375 pull postgres
|
||||||
|
|
||||||
|
3. Pull the `ehazlett/interlock` image to the `interlock` node
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.12:2375 pull ehazlett/interlock
|
||||||
|
|
||||||
|
Each node in the cluster, as well as the `interlock` node, now has the required images stored locally as shown below.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Now that all images are built, pulled, and stored locally, the next step is to start the application.
|
||||||
|
|
||||||
|
## Step 4. Start the voting application
|
||||||
|
|
||||||
|
In the following steps, your launch several containers to the voting application.
|
||||||
|
|
||||||
|
1. If you haven't already, `ssh` into the Swarm `manager` node.
|
||||||
|
|
||||||
|
2. Start the `interlock` container on the `interlock` node
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.12:2375 run --restart=unless-stopped -p 80:80 --name interlock -d ehazlett/interlock --swarm-url tcp://192.168.33.11:3375 --plugin haproxy start
|
||||||
|
|
||||||
|
This command is issued against the `interlock` instance and maps port 80 on the instance to port 80 inside the container. This allows the container to load balance connections coming in over port 80 (HTTP). The command also applies the `--restart=unless-stopped` policy to the container, telling Docker to restart the container if it exits unexpectedly.
|
||||||
|
|
||||||
|
3. Verify the container is running.
|
||||||
|
|
||||||
|
$ docker -H tcp://192.168.33.12:2375 ps
|
||||||
|
|
||||||
|
4. Start a `redis` container on your front end nodes.
|
||||||
|
|
||||||
|
**frontend01**:
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==frontend01" -p 6379:6379 --name redis01 --net mynet -d redis
|
||||||
|
$ docker -H tcp://192.168.33.20:2375 ps
|
||||||
|
|
||||||
|
**frontend02**:
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==frontend02" -p 6379:6379 --name redis02 --net mynet -d redis
|
||||||
|
$ docker -H tcp://192.168.33.21:2375 ps
|
||||||
|
|
||||||
|
These two commands are issued against the Swarm cluster. The commands specify *node constraints*, forcing Swarm to start the contaienrs on `frontend01` and `frontend02`. Port 6379 on each instance is mapped to port 6379 inside of each container for debugging purposes. The command also applies the `--restart=unless-stopped` policy to the containers and attaches them to the `mynet` overlay network.
|
||||||
|
|
||||||
|
5. Start a `web-vote-app` container the frontend nodes.
|
||||||
|
|
||||||
|
**frontend01**:
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==frontend01" -d -p 5000:80 -e WEB_VOTE_NUMBER='01' --name frontend01 --net mynet --hostname votingapp.local web-vote-app
|
||||||
|
|
||||||
|
**frontend02**:
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==frontend02" -d -p 5000:80 -e WEB_VOTE_NUMBER='02' --name frontend02 --net mynet --hostname votingapp.local web-vote-app
|
||||||
|
|
||||||
|
These two commands are issued against the Swarm cluster. The commands
|
||||||
|
specify *node constraints*, forcing Swarm to start the contaienrs on
|
||||||
|
`frontend01` and `frontend02`. Port `5000` on each node is mapped to port
|
||||||
|
`80` inside of each container. This allows connections to come in to each
|
||||||
|
node on port `5000` and be forwarded to port `80` inside of each container.
|
||||||
|
|
||||||
|
Both containers are attached to the `mynet` overlay network and both
|
||||||
|
containers are given the `votingapp-local` hostname. The
|
||||||
|
`--restart=unless-stopped` policy is also applied to these containers.
|
||||||
|
|
||||||
|
4. Start the `postgres` container on the `store` node
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==store" --name pg -e POSTGRES_PASSWORD=pg8675309 --net mynet -p 5432:5432 -d postgres
|
||||||
|
|
||||||
|
This command is issued against the Swarm cluster and starts the container on
|
||||||
|
`store`. It maps port 5432 on the `store` node to port 5432 inside the
|
||||||
|
container and attaches the container to the `mynet` overlay network. The
|
||||||
|
command also inserts the database password into the container via the
|
||||||
|
`POSTGRES_PASSWORD` environment variable and applies the
|
||||||
|
`--restart=unless-stopped` policy to the container.
|
||||||
|
|
||||||
|
Sharing passwords like this is not recommended for production use cases.
|
||||||
|
|
||||||
|
5. Start the `worker01` container on the `worker01` node
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==worker01" -d -e WORKER_NUMBER='01' -e FROM_REDIS_HOST=1 -e TO_REDIS_HOST=2 --name worker01 --net mynet vote-worker
|
||||||
|
|
||||||
|
This command is issued against the Swarm manager and uses a constraint to
|
||||||
|
start the container on the `worker01` node. It passes configuration data
|
||||||
|
into the container via environment variables, telling the worker container
|
||||||
|
to clear the queues on `frontend01` and `frontend02`. It adds the container
|
||||||
|
to the `mynet` overlay network and applies the `--restart=unless-stopped`
|
||||||
|
policy to the container.
|
||||||
|
|
||||||
|
6. Start the `results-app` container on the `store` node
|
||||||
|
|
||||||
|
$ docker run --restart=unless-stopped --env="constraint:node==store" -p 80:80 -d --name results-app --net mynet results-app
|
||||||
|
|
||||||
|
This command starts the results-app container on the `store` node by means
|
||||||
|
of a *node constraint*. It maps port 80 on the `store` node to port 80
|
||||||
|
inside the container. It adds the container to the `mynet` overlay network
|
||||||
|
and applies the `--restart=unless-stopped` policy to the container.
|
||||||
|
|
||||||
|
The application is now fully deployed as shown in the diagram below.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
## Step 5. Test the application
|
||||||
|
|
||||||
|
Now that the application is deployed and running, it's time to test it. To do
|
||||||
|
this, you configure a DNS mapping on the machine where you are running your web
|
||||||
|
browser. This maps the "votingapp.local" DNS name to the public IP address of
|
||||||
|
the `interlock` node.
|
||||||
|
|
||||||
|
1. Configure the DNS name resolution on your local machine for browsing.
|
||||||
|
|
||||||
|
- On Windows machines this is done by adding `votingapp.local <interlock-public-ip>` to the `C:\Windows\System32\Drivers\etc\hosts file`. Modifying this file requires administrator privileges. To open the file with administrator privileges, right-click `C:\Windows\System32\notepad.exe` and select `Run as administrator`. Once Notepad is open, click `file` > `open` and open the file and make the edit.
|
||||||
|
- On OSX machines this is done by adding `votingapp.local <interlock-public-ip>` to `/private/etc/hosts`.
|
||||||
|
- On most Linux machines this is done by adding `votingapp.local <interlock-public-ip>` to `/etc/hosts`.
|
||||||
|
|
||||||
|
Be sure to replace `<interlock-public-ip>` with the public IP address of
|
||||||
|
your `interlock` node. You can find the `interlock` node's Public IP by
|
||||||
|
selecting your `interlock` EC2 Instance from within the AWS EC2 console.
|
||||||
|
|
||||||
|
2. Verify the mapping worked with a `ping` command from your local machine.
|
||||||
|
|
||||||
|
ping votingapp.local
|
||||||
|
Pinging votingapp.local [54.183.164.230] with 32 bytes of data:
|
||||||
|
Reply from 54.183.164.230: bytes=32 time=164ms TTL=42
|
||||||
|
Reply from 54.183.164.230: bytes=32 time=163ms TTL=42
|
||||||
|
Reply from 54.183.164.230: bytes=32 time=169ms TTL=42
|
||||||
|
|
||||||
|
3. Point your web browser to [http://votingapp.local](http://votingapp.local)
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Notice the text at the bottom of the web page. This shows which web
|
||||||
|
container serviced the request. In the diagram above, this is `frontend02`.
|
||||||
|
If you refresh your web browser you should see this change as the Interlock
|
||||||
|
load balancer shares incoming requests across both web containers.
|
||||||
|
|
||||||
|
To see more detailed load balancer data from the Interlock service, point your web browser to [http://stats:interlock@votingapp.local/haproxy?stats](http://stats:interlock@votingapp.local/haproxy?stats)
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
4. Cast your vote. It is recommended to choose "Dogs" ;-)
|
||||||
|
|
||||||
|
5. To see the results of the poll, you can point your web browser at the public IP of the `store` node
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
## Next steps
|
||||||
|
|
||||||
|
Congratulations. You have successfully walked through manually deploying a
|
||||||
|
microservice-based application to a Swarm cluster. Of course, not every
|
||||||
|
deployment goes smoothly. Now that you've learned how to successfully deploy an
|
||||||
|
application at scale, you should learn [what to consider when troubleshooting
|
||||||
|
large applications running on a Swarm cluster](05-troubleshoot.md).
|
||||||
|
|
@ -0,0 +1,217 @@
|
||||||
|
<!--[metadata]>
|
||||||
|
+++
|
||||||
|
title = "Troubleshoot the application"
|
||||||
|
description = "Try Swarm at scale"
|
||||||
|
keywords = ["docker, swarm, scale, voting, application, certificates"]
|
||||||
|
[menu.main]
|
||||||
|
parent="scale_swarm"
|
||||||
|
+++
|
||||||
|
<![end-metadata]-->
|
||||||
|
|
||||||
|
# Troubleshoot the application
|
||||||
|
|
||||||
|
It's a fact of life that things fail. With this in mind, it's important to
|
||||||
|
understand what happens when failures occur and how to mitigate them. The
|
||||||
|
following sections cover different failure scenarios:
|
||||||
|
|
||||||
|
- [Swarm manager failures](#swarm-manager-failures)
|
||||||
|
- [Consul (discovery backend) failures](#consul-discovery-backend-failures)
|
||||||
|
- [Interlock load balancer failures](#interlock-load-balancer-failures)
|
||||||
|
- [Web (web-vote-app) failures](#web-web-vote-app-failures)
|
||||||
|
- [Redis failures](#redis-failures)
|
||||||
|
- [Worker (vote-worker) failures](#worker-vote-worker-failures)
|
||||||
|
- [Postgres failures](#postgres-failures)
|
||||||
|
- [Results-app failures](#results-app-failures)
|
||||||
|
- [Infrastructure failures](#infrastructure-failures)
|
||||||
|
|
||||||
|
## Swarm manager failures
|
||||||
|
|
||||||
|
In it's current configuration, the Swarm cluster only has single manager
|
||||||
|
container running on a single node. If the container exits or the node fails,
|
||||||
|
you will not be able to administer the cluster until you either; fix it, or
|
||||||
|
replace it.
|
||||||
|
|
||||||
|
If the failure is the Swarm manager container unexpectedly exiting, Docker will
|
||||||
|
automatically attempt to restart it. This is because the container was started
|
||||||
|
with the `--restart=unless-stopped` switch.
|
||||||
|
|
||||||
|
While the Swarm manager is unavailable, the application will continue to work in
|
||||||
|
its current configuration. However, you will not be able to provision more nodes
|
||||||
|
or containers until you have a working Swarm manager.
|
||||||
|
|
||||||
|
Docker Swarm supports high availability for Swarm managers. This allows a single
|
||||||
|
Swarm cluster to have two or more managers. One manager is elected as the
|
||||||
|
primary manager and all others operate as secondaries. In the event that the
|
||||||
|
primary manager fails, one of the secondaries is elected as the new primary, and
|
||||||
|
cluster operations continue gracefully. If you are deploying multiple Swarm
|
||||||
|
managers for high availability, you should consider spreading them across
|
||||||
|
multiple failure domains within your infrastructure.
|
||||||
|
|
||||||
|
## Consul (discovery backend) failures
|
||||||
|
|
||||||
|
The Swarm cluster that you have deployed has a single Consul container on a
|
||||||
|
single node performing the cluster discovery service. In this setup, if the
|
||||||
|
Consul container exits or the node fails, the application will continue to
|
||||||
|
operate in its current configuration. However, certain cluster management
|
||||||
|
operations will fail. These include registering new containers in the cluster
|
||||||
|
and making lookups against the cluster configuration.
|
||||||
|
|
||||||
|
If the failure is the `consul` container unexpectedly exiting, Docker will
|
||||||
|
automatically attempt to restart it. This is because the container was started
|
||||||
|
with the `--restart=unless-stopped` switch.
|
||||||
|
|
||||||
|
The `Consul`, `etcd`, and `Zookeeper` discovery service backends support various
|
||||||
|
options for high availability. These include Paxos/Raft quorums. You should
|
||||||
|
follow existing best practices for deploying HA configurations of your chosen
|
||||||
|
discover service backend. If you are deploying multiple discovery service
|
||||||
|
instances for high availability, you should consider spreading them across
|
||||||
|
multiple failure domains within your infrastructure.
|
||||||
|
|
||||||
|
If you operate your Swarm cluster with a single discovery backend service and
|
||||||
|
this service fails and is unrecoverable, you can start a new empty instance of
|
||||||
|
the discovery backend and the Swarm agents on each node in the cluster will
|
||||||
|
repopulate it.
|
||||||
|
|
||||||
|
|
||||||
|
### Handling failures
|
||||||
|
|
||||||
|
There are many reasons why containers can fail. However, Swarm does not attempt
|
||||||
|
to restart failed containers.
|
||||||
|
|
||||||
|
One way to automatically restart failed containers is to explicitly start them
|
||||||
|
with the `--restart=unless-stopped` flag. This will tell the local Docker daemon
|
||||||
|
to attempt to restart the container if it unexpectedly exits. This will only
|
||||||
|
work in situations where the node hosting the container and it's Docker daemon
|
||||||
|
are still up. This cannot restart a container if the node hosting it has failed,
|
||||||
|
or if the Docker daemon itself has failed.
|
||||||
|
|
||||||
|
Another way is to have an external tool (external to the cluster) monitor the
|
||||||
|
state of your application, and make sure that certain service levels are
|
||||||
|
maintained. These service levels can include things like "have at least 10 web
|
||||||
|
server containers running". In this scenario, if the number of web containers
|
||||||
|
drops below 10, the tool will attempt to start more.
|
||||||
|
|
||||||
|
In our simple voting-app example, the front-end is scalable and serviced by a
|
||||||
|
load balancer. In the event that on the of the two web containers fails (or the
|
||||||
|
AWS instance that is hosting it), the load balancer will stop routing requests
|
||||||
|
to it and send all requests the surviving web container. This solution is highly
|
||||||
|
scalable meaning you can have up to *n* web containers behind the load balancer.
|
||||||
|
|
||||||
|
## Interlock load balancer failures
|
||||||
|
|
||||||
|
The environment that you have provisioned has a single
|
||||||
|
[interlock](https://github.com/ehazlett/interlock) load balancer container
|
||||||
|
running on a single node. In this setup, if the container exits or node fails,
|
||||||
|
the application will no longer be able to service incoming requests and the
|
||||||
|
application will be unavailable.
|
||||||
|
|
||||||
|
If the failure is the `interlock` container unexpectedly exiting, Docker will
|
||||||
|
automatically attempt to restart it. This is because the container was started
|
||||||
|
with the `--restart=unless-stopped` switch.
|
||||||
|
|
||||||
|
It is possible to build an HA Interlock load balancer configuration. One such
|
||||||
|
way is to have multiple Interlock containers on multiple nodes. You can then use
|
||||||
|
DNS round robin, or other technologies, to load balance across each Interlock
|
||||||
|
container. That way, if one Interlock container or node goes down, the others
|
||||||
|
will continue to service requests.
|
||||||
|
|
||||||
|
If you deploy multiple interlock load balancers, you should consider spreading
|
||||||
|
them across multiple failure domains within your infrastructure.
|
||||||
|
|
||||||
|
## Web (web-vote-app) failures
|
||||||
|
|
||||||
|
The environment that you have configured has two web-vote-app containers running
|
||||||
|
on two separate nodes. They operate behind an Interlock load balancer that
|
||||||
|
distributes incoming connections across both.
|
||||||
|
|
||||||
|
In the event that one of the web containers or nodes fails, the load balancer
|
||||||
|
will start directing all incoming requests to surviving instance. Once the
|
||||||
|
failed instance is back up, or a replacement is added, the load balancer will
|
||||||
|
add it to the configuration and start sending a portion of the incoming requests
|
||||||
|
to it.
|
||||||
|
|
||||||
|
For highest availability you should deploy the two frontend web services
|
||||||
|
(`frontend01` and `frontend02`) in different failure zones within your
|
||||||
|
infrastructure. You should also consider deploying more.
|
||||||
|
|
||||||
|
## Redis failures
|
||||||
|
|
||||||
|
If the a `redis` container fails, it's partnered `web-vote-app` container will
|
||||||
|
not function correctly. The best solution in this instance might be to configure
|
||||||
|
health monitoring that verifies the ability to write to each Redis instance. If
|
||||||
|
an unhealthy `redis` instance is encountered, remove the `web-vote-app` and
|
||||||
|
`redis` combination and attempt remedial actions.
|
||||||
|
|
||||||
|
## Worker (vote-worker) failures
|
||||||
|
|
||||||
|
If the worker container exits, or the node that is hosting it fails, the redis
|
||||||
|
containers will queue votes until the worker container comes back up. This
|
||||||
|
situation can prevail indefinitely, though a worker needs to come back at some
|
||||||
|
point and process the votes.
|
||||||
|
|
||||||
|
If the failure is the `worker01` container unexpectedly exiting, Docker will
|
||||||
|
automatically attempt to restart it. This is because the container was started
|
||||||
|
with the `--restart=unless-stopped` switch.
|
||||||
|
|
||||||
|
## Postgres failures
|
||||||
|
|
||||||
|
This application does not implement any for of HA or replication for Postgres.
|
||||||
|
Therefore losing the Postgres container would cause the application to fail and
|
||||||
|
potential lose or corrupt data. A better solution would be to implement some
|
||||||
|
form of Postgres HA or replication.
|
||||||
|
|
||||||
|
## Results-app failures
|
||||||
|
|
||||||
|
If the results-app container exits, you will not be able to browse to the
|
||||||
|
results of the poll until the container is back up and running. Results will
|
||||||
|
continue to be collected and counted, you will just not be able to view results
|
||||||
|
until the container is back up and running.
|
||||||
|
|
||||||
|
The results-app container was started with the `--restart=unless-stopped` flag
|
||||||
|
meaning that the Docker daemon will automatically attempt to restart it unless
|
||||||
|
it was administratively stopped.
|
||||||
|
|
||||||
|
## Infrastructure failures
|
||||||
|
|
||||||
|
There are many ways in which the infrastructure underpinning your applications
|
||||||
|
can fail. However, there are a few best practices that can be followed to help
|
||||||
|
mitigate and offset these failures.
|
||||||
|
|
||||||
|
One of these is to deploy infrastructure components over as many failure domains
|
||||||
|
as possible. On a service such as AWS, this often translates into balancing
|
||||||
|
infrastructure and services across multiple AWS Availability Zones (AZ) within a
|
||||||
|
Region.
|
||||||
|
|
||||||
|
To increase the availability of our Swarm cluster you could:
|
||||||
|
|
||||||
|
* Configure the Swarm manager for HA and deploy HA nodes in different AZs
|
||||||
|
* Configure the Consul discovery service for HA and deploy HA nodes in different AZs
|
||||||
|
* Deploy all scalable components of the application across multiple AZs
|
||||||
|
|
||||||
|
This configuration is shown in the diagram below.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
This will allow us to lose an entire AZ and still have our cluster and
|
||||||
|
application operate.
|
||||||
|
|
||||||
|
But it doesn't have to stop there. Some applications can be balanced across AWS
|
||||||
|
Regions. In our example we might deploy parts of our cluster and application in
|
||||||
|
the `us-west-1` Region and the rest in `us-east-1`. It's even becoming possible
|
||||||
|
to deploy services across cloud providers, or have balance services across
|
||||||
|
public cloud providers and your on premises date centers!
|
||||||
|
|
||||||
|
The diagram below shows parts of the application and infrastructure deployed
|
||||||
|
across AWS and Microsoft Azure. But you could just as easily replace one of
|
||||||
|
those cloud providers with your own on premises data center. In these scenarios,
|
||||||
|
network latency and reliability is key to a smooth and workable solution.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
## Related information
|
||||||
|
|
||||||
|
The application in this example could be deployed on Docker Universal Control Plane (UCP) which is currently in Beta release. To try the application on UCP in your environment, [request access to the UCP Beta release](https://www.docker.com/products/docker-universal-control-plane). Other useful documentation:
|
||||||
|
|
||||||
|
* [Plan for Swarm in production](../plan-for-production.md)
|
||||||
|
* [Swarm and container networks](../networking.md)
|
||||||
|
* [High availability in Docker Swarm](../multi-manager-setup.md)
|
||||||
|
|
@ -0,0 +1,35 @@
|
||||||
|
<!--[metadata]>
|
||||||
|
+++
|
||||||
|
title = "Try Swarm at scale"
|
||||||
|
description = "Try Swarm at scale"
|
||||||
|
keywords = ["docker, swarm, scale, voting, application, certificates"]
|
||||||
|
[menu.main]
|
||||||
|
parent="workw_swarm"
|
||||||
|
identifier="scale_swarm"
|
||||||
|
weight=-35
|
||||||
|
+++
|
||||||
|
<![end-metadata]-->
|
||||||
|
|
||||||
|
# Try Swarm at scale
|
||||||
|
|
||||||
|
Using this example, you deploy a voting application on a Swarm cluster. This
|
||||||
|
example illustrates a typical development process. After you establish an
|
||||||
|
infrastructure, you create a Swarm cluster and deploy the application against
|
||||||
|
the cluster.
|
||||||
|
|
||||||
|
After building and manually deploying the voting application, you'll construct a
|
||||||
|
Docker Compose file. You (or others) can use the file to deploy and scale the
|
||||||
|
application further. The article also provides a troubleshooting section you can
|
||||||
|
use while developing or deploying the voting application.
|
||||||
|
|
||||||
|
The sample is written for a novice network administrator. You should have a
|
||||||
|
basic skills on Linux systems, `ssh` experience, and some understanding of the
|
||||||
|
AWS service from Amazon. Some knowledge of Git is also useful but not strictly
|
||||||
|
required. This example takes approximately an hour to complete and has the
|
||||||
|
following steps:
|
||||||
|
|
||||||
|
- [Learn the application architecture](01-about.md)
|
||||||
|
- [Deploy your infrastructure](02-deploy-infra.md)
|
||||||
|
- [Setup cluster resources](03-create-cluster.md)
|
||||||
|
- [Deploy the application](04-deploy-app.md)
|
||||||
|
- [Troubleshoot the application](05-troubleshoot.md)
|
||||||
Loading…
Reference in New Issue