mirror of https://github.com/docker/docs.git
145 lines
4.6 KiB
Markdown
145 lines
4.6 KiB
Markdown
---
|
|
title: Add labels to cluster nodes
|
|
description: Learn how to add metadata to cluster nodes that can be used to specify constraints when deploying services.
|
|
keywords: cluster, node, label, swarm, metadata
|
|
---
|
|
|
|
With Docker UCP, you can add labels to your nodes. Labels are metadata that
|
|
describe the node, like its role (development, QA, production), its region
|
|
(US, EU, APAC), or the kind of disk (hdd, ssd). Once you have labeled your
|
|
nodes, you can add deployment constraints to your services, to ensure they
|
|
are scheduled on a node with a specific label.
|
|
|
|
For example, you can apply labels based on their role in the development
|
|
lifecycle, or the hardware resources they have.
|
|
|
|
|
|
|
|
Don't create labels for authorization and permissions to resources.
|
|
Instead, use resource sets, either UCP collections or Kubernetes namespaces,
|
|
to organize access to your cluster.
|
|
[Learn about managing access with resource sets](../../authorization/group-resources.md).
|
|
|
|
## Apply labels to a node
|
|
|
|
In this example we'll apply the `ssd` label to a node. Then we'll deploy
|
|
a service with a deployment constraint to make sure the service is always
|
|
scheduled to run on a node that has the `ssd` label.
|
|
|
|
Log in with administrator credentials in the UCP web UI, navigate to the
|
|
**Nodes** page, and choose the node you want to apply labels to. In the
|
|
details pane, click **Configure**.
|
|
|
|
In the **Edit Node** page, scroll down to the **Labels** section.
|
|
|
|
Click **Add Label**, and add a label with the key `disk` and a value of `ssd`.
|
|
|
|
{: .with-border}
|
|
|
|
Click **Save** and dismiss the **Edit Node** page. In the node's details
|
|
pane, click **Labels** to view the labels that are applied to the node.
|
|
|
|
You can also do this from the CLI by running:
|
|
|
|
```bash
|
|
docker node update --label-add <key>=<value> <node-id>
|
|
```
|
|
|
|
## Deploy a service with constraints
|
|
|
|
When deploying a service, you can specify constraints, so that the service gets
|
|
scheduled only on a node that has a label that fulfills all of the constraints
|
|
you specify.
|
|
|
|
In this example, when users deploy a service, they can add a constraint for the
|
|
service to be scheduled only on nodes that have SSD storage:
|
|
`node.labels.disk == ssd`.
|
|
|
|
Navigate to the **Stacks** page. Name the new stack "wordpress", and in the
|
|
**Mode** dropdown, check **Swarm Services**.
|
|
|
|
In the **docker-compose.yml** editor, paste the following stack file.
|
|
|
|
```
|
|
version: "3.1"
|
|
|
|
services:
|
|
db:
|
|
image: mysql:5.7
|
|
deploy:
|
|
placement:
|
|
constraints:
|
|
- node.labels.disk == ssd
|
|
restart_policy:
|
|
condition: on-failure
|
|
networks:
|
|
- wordpress-net
|
|
environment:
|
|
MYSQL_ROOT_PASSWORD: wordpress
|
|
MYSQL_DATABASE: wordpress
|
|
MYSQL_USER: wordpress
|
|
MYSQL_PASSWORD: wordpress
|
|
wordpress:
|
|
depends_on:
|
|
- db
|
|
image: wordpress:latest
|
|
deploy:
|
|
replicas: 1
|
|
placement:
|
|
constraints:
|
|
- node.labels.disk == ssd
|
|
restart_policy:
|
|
condition: on-failure
|
|
max_attempts: 3
|
|
networks:
|
|
- wordpress-net
|
|
ports:
|
|
- "8000:80"
|
|
environment:
|
|
WORDPRESS_DB_HOST: db:3306
|
|
WORDPRESS_DB_PASSWORD: wordpress
|
|
|
|
networks:
|
|
wordpress-net:
|
|
```
|
|
|
|
Click **Create** to deploy the stack, and when the stack deploys,
|
|
click **Done**.
|
|
|
|
|
|
|
|
Navigate to the **Nodes** page, and click the node that has the
|
|
`disk` label. In the details pane, click the **Inspect Resource**
|
|
dropdown and select **Containers**.
|
|
|
|
|
|
|
|
Dismiss the filter and navigate to the **Nodes** page. Click a node that
|
|
doesn't have the `disk` label. In the details pane, click the
|
|
**Inspect Resource** dropdown and select **Containers**. There are no
|
|
WordPress containers scheduled on the node. Dismiss the filter.
|
|
|
|
## Add a constraint to a service by using the UCP web UI
|
|
|
|
You can declare the deployment constraints in your docker-compose.yml file or
|
|
when you're creating a stack. Also, you can apply them when you're creating
|
|
a service.
|
|
|
|
To check if a service has deployment constraints, navigate to the
|
|
**Services** page and choose the service that you want to check.
|
|
In the details pane, click **Constraints** to list the constraint labels.
|
|
|
|
To edit the constraints on the service, click **Configure** and select
|
|
**Details** to open the **Update Service** page. Click **Scheduling** to
|
|
view the constraints.
|
|
|
|
|
|
|
|
You can add or remove deployment constraints on this page.
|
|
|
|
## Where to go next
|
|
|
|
- [Store logs in an external system](store-logs-in-an-external-system.md)
|
|
|
|
|