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Merge pull request #10267 from satnam6502/guestbook-go 

Update guestbook-go example
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Maxwell Forbes 2015-06-25 13:51:27 -07:00
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141
guestbook-go/README.md
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@ -4,37 +4,38 @@ This example shows how to build a simple multi-tier web application using Kubern
### Step Zero: Prerequisites
This example assumes that you have forked the repository and [turned up a Kubernetes cluster](../../docs/getting-started-guides):
```shell
$ cd kubernetes
$ hack/dev-build-and-up.sh
```
This example assumes that you have a working cluster (see the [Getting Started Guides](../../docs/getting-started-guides)).
A Google Container Engine specific version of this tutoriual can be found at [https://cloud.google.com/container-engine/docs/tutorials/guestbook](https://cloud.google.com/container-engine/docs/tutorials/guestbook).
### Step One: Turn up the redis master.
Use the file `examples/guestbook-go/redis-master-controller.json` to create a [replication controller](../../docs/replication-controller.md) which manages a single [pod](../../docs/pods.md). The pod runs a redis key-value server in a container. Using a replication controller is the preferred way to launch long-running pods, even for 1 replica, so the pod will benefit from self-healing mechanism in kubernetes.
Use the file `examples/guestbook-go/redis-master-controller.json` to create a [replication controller](../../docs/replication-controller.md) which manages a single [pod](../../docs/pods.md). The pod runs a redis key-value server in a container. Using a replication controller is the preferred way to launch long-running pods, even for 1 replica, so the pod will benefit from self-healing mechanism in Kubernetes.
Create the redis master replication controller in your Kubernetes cluster using the `kubectl` CLI:
Create the redis master replication controller in your Kubernetes cluster using the `kubectl` CLI and the file that specifies the replication controller [examples/guestbook-go/redis-master-controller.json](redis-master-controller.json):
```shell
$ kubectl create -f examples/guestbook-go/redis-master-controller.json
replicationcontrollers/redis-master
```
Once that's up you can list the replication controllers in the cluster:
```shell
$ kubectl get rc
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
redis-master-controller redis-master gurpartap/redis name=redis,role=master 1
redis-master redis-master gurpartap/redis app=redis,role=master 1
...
```
List pods in cluster to verify the master is running. You'll see a single redis master pod. It will also display the machine that the pod is running on once it gets placed (may take up to thirty seconds).
List pods in the cluster to verify the master is running. You'll see a single redis master pod and perhaps
some other system pods. The state of the pod and number of restarts and the duration it has been
executing for will also be reported (may take up to thirty seconds for the state to becoming ready and running).
```shell
$ kubectl get pods
POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
redis-master-y06lj 10.244.3.4 kubernetes-minion-bz1p/104.154.61.231 name=redis,role=master Running 8 seconds
redis-master gurpartap/redis Running 3 seconds
NAME READY REASON RESTARTS AGE
redis-master-xx4uv 1/1 Running 0 1m
...
```
If you ssh to that machine, you can run `docker ps` to see the actual pod:
@ -52,30 +53,34 @@ d5c458dabe50 gurpartap/redis:latest "/usr/local/bin/redi
### Step Two: Turn up the master service.
A Kubernetes '[service](../../docs/services.md)' is a named load balancer that proxies traffic to one or more containers. The services in a Kubernetes cluster are discoverable inside other containers via environment variables or DNS. Services find the containers to load balance based on pod labels.
The pod that you created in Step One has the label `name=redis` and `role=master`. The selector field of the service determines which pods will receive the traffic sent to the service. Use the file `examples/guestbook-go/redis-master-service.json` to create the service in the `kubectl` cli:
The pod that you created in Step One has the label `app=redis` and `role=master`. The selector field of the service determines which pods will receive the traffic sent to the service. Use the file [examples/guestbook-go/redis-master-service.json](redis-master-service.json) to create the service in the `kubectl` cli:
```shell
$ kubectl create -f examples/guestbook-go/redis-master-service.json
services/redis-master
$ kubectl get services
NAME LABELS SELECTOR IP(S) PORT(S)
redis-master name=redis,role=master name=redis,role=master 10.0.11.173 6379/TCP
redis-master app=redis,role=master app=redis,role=master 10.0.136.3 6379/TCP
...
```
This will cause all new pods to see the redis master apparently running on $REDIS_MASTER_SERVICE_HOST at port 6379, or running on 'redis-master:6379'. Once created, the service proxy on each node is configured to set up a proxy on the specified port (in this case port 6379).
This will cause all new pods to see the redis master apparently running on `$REDIS_MASTER_SERVICE_HOST` at port 6379, or running on `redis-master:6379`. Once created, the service proxy on each node is configured to set up a proxy on the specified port (in this case port 6379).
### Step Three: Turn up the replicated slave pods.
Although the redis master is a single pod, the redis read slaves are a 'replicated' pod. In Kubernetes, a replication controller is responsible for managing multiple instances of a replicated pod.
Use the file `examples/guestbook-go/redis-slave-controller.json` to create the replication controller:
Use the file [examples/guestbook-go/redis-slave-controller.json](redis-slave-controller.json) to create the replication controller:
```shell
$ kubectl create -f examples/guestbook-go/redis-slave-controller.json
replicationcontrollers/redis-slave
$ kubectl get rc
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
redis-master redis-master gurpartap/redis name=redis,role=master 1
redis-slave redis-slave gurpartap/redis name=redis,role=slave 2
redis-master redis-master gurpartap/redis app=redis,role=master 1
redis-slave redis-slave gurpartap/redis app=redis,role=slave 2
...
```
The redis slave configures itself by looking for the redis-master service name:port pair. In particular, the redis slave is started with the following command:
@ -88,100 +93,109 @@ Once that's up you can list the pods in the cluster, to verify that the master a
```shell
$ kubectl get pods
POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
redis-master-y06lj 10.244.3.4 kubernetes-minion-bz1p/104.154.61.231 name=redis,role=master Running 5 minutes
redis-master gurpartap/redis Running 5 minutes
redis-slave-3psic 10.244.0.4 kubernetes-minion-mluf/104.197.10.10 name=redis,role=slave Running 38 seconds
redis-slave gurpartap/redis Running 33 seconds
redis-slave-qtigf 10.244.2.4 kubernetes-minion-rcgd/130.211.122.180 name=redis,role=slave Running 38 seconds
redis-slave gurpartap/redis Running 36 seconds
NAME READY REASON RESTARTS AGE
redis-master-xx4uv 1/1 Running 0 18m
redis-slave-b6wj4 1/1 Running 0 1m
redis-slave-iai40 1/1 Running 0 1m
...
```
You will see a single redis master pod and two redis slave pods.
### Step Four: Create the redis slave service.
Just like the master, we want to have a service to proxy connections to the read slaves. In this case, in addition to discovery, the slave service provides transparent load balancing to clients. The service specification for the slaves is in `examples/guestbook-go/redis-slave-service.json`
Just like the master, we want to have a service to proxy connections to the read slaves. In this case, in addition to discovery, the slave service provides transparent load balancing to clients. The service specification for the slaves
is in [examples/guestbook-go/redis-slave-service.json](redis-slave-service.json)
This time the selector for the service is `name=redis,role=slave`, because that identifies the pods running redis slaves. It may also be helpful to set labels on your service itself--as we've done here--to make it easy to locate them later.
This time the selector for the service is `app=redis,role=slave`, because that identifies the pods running redis slaves. It may also be helpful to set labels on your service itself--as we've done here--to make it easy to locate them later.
Now that you have created the service specification, create it in your cluster with the `kubectl` CLI:
```shell
$ kubectl create -f examples/guestbook-go/redis-slave-service.json
services/redis-slave
$ kubectl get services
NAME LABELS SELECTOR IP(S) PORT(S)
redis-master name=redis,role=master name=redis,role=master 10.0.11.173 6379/TCP
redis-slave name=redis,role=slave name=redis,role=slave 10.0.234.24 6379/TCP
redis-master app=redis,role=master app=redis,role=master 10.0.136.3 6379/TCP
redis-slave app=redis,role=slave app=redis,role=slave 10.0.21.92 6379/TCP
...
```
### Step Five: Create the guestbook pod.
This is a simple Go net/http ([negroni](https://github.com/codegangsta/negroni) based) server that is configured to talk to either the slave or master services depending on whether the request is a read or a write. It exposes a simple JSON interface, and serves a jQuery-Ajax based UX. Like the redis read slaves it is a replicated service instantiated by a replication controller.
The pod is described in the file `examples/guestbook-go/guestbook-controller.json`. Using this file, you can turn up your guestbook with:
The pod is described in the file [examples/guestbook-go/guestbook-controller.json](guestbook-controller.json). Using this file, you can turn up your guestbook with:
```shell
$ kubectl create -f examples/guestbook-go/guestbook-controller.json
replicationcontrollers/guestbook
$ kubectl get replicationControllers
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
guestbook guestbook kubernetes/guestbook:v2 name=guestbook 3
redis-master redis-master gurpartap/redis name=redis,role=master 1
redis-slave redis-slave gurpartap/redis name=redis,role=slave 2
guestbook guestbook kubernetes/guestbook:v2 app=guestbook 3
redis-master redis-master gurpartap/redis app=redis,role=master 1
redis-slave redis-slave gurpartap/redis app=redis,role=slave 2
...
```
Once that's up (it may take ten to thirty seconds to create the pods) you can list the pods in the cluster, to verify that the master, slaves and guestbook frontends are running:
```shell
POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
guestbook-1xzms 10.244.1.6 kubernetes-minion-q6w5/23.236.54.97 name=guestbook Running 40 seconds
guestbook kubernetes/guestbook:v2 Running 35 seconds
guestbook-9ksu4 10.244.0.5 kubernetes-minion-mluf/104.197.10.10 name=guestbook Running 40 seconds
guestbook kubernetes/guestbook:v2 Running 34 seconds
guestbook-lycwm 10.244.1.7 kubernetes-minion-q6w5/23.236.54.97 name=guestbook Running 40 seconds
guestbook kubernetes/guestbook:v2 Running 35 seconds
redis-master-y06lj 10.244.3.4 kubernetes-minion-bz1p/104.154.61.231 name=redis,role=master Running 8 minutes
redis-master gurpartap/redis Running 8 minutes
redis-slave-3psic 10.244.0.4 kubernetes-minion-mluf/104.197.10.10 name=redis,role=slave Running 3 minutes
redis-slave gurpartap/redis Running 3 minutes
redis-slave-qtigf 10.244.2.4 kubernetes-minion-rcgd/130.211.122.180 name=redis,role=slave Running 3 minutes
redis-slave gurpartap/redis Running 3 minutes
$ kubectl get pods
NAME READY REASON RESTARTS AGE
guestbook-3crgn 1/1 Running 0 2m
guestbook-gv7i6 1/1 Running 0 2m
guestbook-x405a 1/1 Running 0 2m
redis-master-xx4uv 1/1 Running 0 23m
redis-slave-b6wj4 1/1 Running 0 6m
redis-slave-iai40 1/1 Running 0 6m
...
```
You will see a single redis master pod, two redis slaves, and three guestbook pods.
### Step Six: Create the guestbook service.
Just like the others, you want a service to group your guestbook pods. The service specification for the guestbook is in `examples/guestbook-go/guestbook-service.json`. There's a twist this time - because we want it to be externally visible, we set `"type": "LoadBalancer"` for the service.
Just like the others, you want a service to group your guestbook pods. The service specification for the guestbook is in [examples/guestbook-go/guestbook-service.json](guestbook-service.json). There's a twist this time - because we want it to be externally visible, we set `"type": "LoadBalancer"` for the service.
```shell
$ kubectl create -f examples/guestbook-go/guestbook-service.json
An external load-balanced service was created. On many platforms (e.g. Google Compute Engine),
you will also need to explicitly open a Firewall rule for the service port(s) (tcp:3000) to serve traffic.
See https://github.com/GoogleCloudPlatform/kubernetes/tree/master/docs/services-firewall.md for more details.
$ kubectl get services
NAME LABELS SELECTOR IP(S) PORT(S)
guestbook name=guestbook name=guestbook 10.0.114.109 3000/TCP
redis-master name=redis,role=master name=redis,role=master 10.0.11.173 6379/TCP
redis-slave name=redis,role=slave name=redis,role=slave 10.0.234.24 6379/TCP
guestbook app=guestbook app=guestbook 10.0.217.218 3000/TCP
146.148.81.8
redis-master app=redis,role=master app=redis,role=master 10.0.136.3 6379/TCP
redis-slave app=redis,role=slave app=redis,role=slave 10.0.21.92 6379/TCP
...
```
To play with the service itself, find the external IP of the load balancer:
```shell
$ kubectl get services guestbook -o template --template='{{(index .status.loadBalancer.ingress 0).ip}}'
104.154.63.66$
```
and then visit port 3000 of that IP address e.g. `http://104.154.63.66:3000`.
To play with the service itself, find the external IP of the load balancer. This is reported in the IP column for the guestbook services which shows
an internal IP address 10.0.217.218 and an external IP address 146.148.81.8 (you may need to scroll right in the box
above to see the IP column. It make take a few moments to show up) after which you can
visit port 3000 of that IP address e.g. `http://146.148.81.8:3000`.
**NOTE:** You may need to open the firewall for port 3000 using the [console][cloud-console] or the `gcloud` tool. The following command will allow traffic from any source to instances tagged `kubernetes-minion`:
```shell
$ gcloud compute firewall-rules create --allow=tcp:3000 --target-tags=kubernetes-minion kubernetes-minion-3000
```
For Google Container Engine clusters the nodes are tagged differently. See the [Google Container Engine Guestbook example](https://cloud.google.com/container-engine/docs/tutorials/guestbook).
When you visit the external IP address of the guestbook service in a browser you should see something like this:
![Guestbook](guestbook-page.png)
If you are running Kubernetes locally, you can just visit http://localhost:3000
For details about limiting traffic to specific sources, see the [GCE firewall documentation][gce-firewall-docs].
For details about limiting traffic to specific sources, see the [Google Compute Engine firewall documentation][gce-firewall-docs].
[cloud-console]: https://console.developer.google.com
[gce-firewall-docs]: https://cloud.google.com/compute/docs/networking#firewalls
@ -199,11 +213,8 @@ redis-slave-controller
redis-slave
```
To turn down a Kubernetes cluster:
```shell
$ cluster/kube-down.sh
```
To turn down your Kubernetes cluster follow the appropriate instructions in the
[Getting Started Guides](../../docs/getting-started-guides) for your type of cluster.
[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/examples/guestbook-go/README.md?pixel)]()

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@ -4,18 +4,18 @@
"metadata":{
"name":"guestbook",
"labels":{
"name":"guestbook"
"app":"guestbook"
}
},
"spec":{
"replicas":3,
"selector":{
"name":"guestbook"
"app":"guestbook"
},
"template":{
"metadata":{
"labels":{
"name":"guestbook"
"app":"guestbook"
}
},
"spec":{

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guestbook-go/guestbook-service.json
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@ -4,7 +4,7 @@
"metadata":{
"name":"guestbook",
"labels":{
"name":"guestbook"
"app":"guestbook"
}
},
"spec":{
@ -15,7 +15,7 @@
}
],
"selector":{
"name":"guestbook"
"app":"guestbook"
},
"type": "LoadBalancer"
}

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guestbook-go/redis-master-controller.json
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@ -5,20 +5,20 @@
"metadata":{
"name":"redis-master",
"labels":{
"name":"redis",
"app":"redis",
"role":"master"
}
},
"spec":{
"replicas":1,
"selector":{
"name":"redis",
"app":"redis",
"role":"master"
},
"template":{
"metadata":{
"labels":{
"name":"redis",
"app":"redis",
"role":"master"
}
},

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guestbook-go/redis-master-service.json
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@ -4,7 +4,7 @@
"metadata":{
"name":"redis-master",
"labels":{
"name":"redis",
"app":"redis",
"role":"master"
}
},
@ -16,7 +16,7 @@
}
],
"selector":{
"name":"redis",
"app":"redis",
"role":"master"
}
}

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guestbook-go/redis-slave-controller.json
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@ -5,20 +5,20 @@
"metadata":{
"name":"redis-slave",
"labels":{
"name":"redis",
"app":"redis",
"role":"slave"
}
},
"spec":{
"replicas":2,
"selector":{
"name":"redis",
"app":"redis",
"role":"slave"
},
"template":{
"metadata":{
"labels":{
"name":"redis",
"app":"redis",
"role":"slave"
}
},

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@ -4,7 +4,7 @@
"metadata":{
"name":"redis-slave",
"labels":{
"name":"redis",
"app":"redis",
"role":"slave"
}
},
@ -16,7 +16,7 @@
}
],
"selector":{
"name":"redis",
"app":"redis",
"role":"slave"
}
}