Select a cluster to distribute applications - Alibaba Cloud Distributed Cloud Container Platform| Alibaba Cloud Documentation Center

When you use a master instance of ACK One to distribute applications, you must select the cluster to which you want to distribute the applications. This topic describes how to select a cluster that is associated with a master instance to distribute applications by specifying the cluster name or a label as the cluster selector.

Prerequisites

The kubeconfig file of the master instance is obtained from the ACK One console by using an account with the developer role. A kubectl client is connected to the master instance.
Namespaces and resource quotas are configured by the master instance administrator. For more information, see Manage namespaces and resource quotas.
Multiple ACK clusters are associated with the master instance. For more information, see Associate clusters with a master instance.
The AMC command-line tool is installed. For more information, see Use AMC.

Method 1: Specify a cluster name

Run the following command to query the names of the clusters that are associated with a master instance:

kubectl get managedclusters

Expected output:

NAME                     HUB ACCEPTED   MANAGED CLUSTER URLS   JOINED   AVAILABLE   AGE
managedcluster-c5***z9   true                                  True     True        12d
managedcluster-c1***e5   true                                  True     True        12d

Create a Policy object with the following code block.

Replace <clusterid1> with the id of the cluster to which you want to distribute applications.

apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
  name: cluster-beijing
  namespace: demo
type: topology
properties:
  clusters: ["<clusterid1>"]   # The name of the cluster to which you want to distribute applications. Specify multiple cluster names in the following format: ["<clusterid1>", "<clusterid2>"...].


Parameter	Description
`type: topology`	A Policy object of the Topology type allows you to define the clusters to which applications are distributed. A Policy object of the Override type allows you to override the configurations of applications.
`properties. clusters`	You can specify multiple cluster id to distribute applications to multiple clusters.

Method 2: Specify a label as the cluster id

Run the following command to query the names of the clusters that are associated with a master instance:

kubectl get managedclusters

Expected output:

NAME                     HUB ACCEPTED   MANAGED CLUSTER URLS   JOINED   AVAILABLE   AGE
managedcluster-c5***z9   true                                  True     True        12d
managedcluster-c1***e5   true                                  True     True        12d

Run the following command to add a label to a cluster that is associated with the master instance:
Replace <clusterid> with the name of the cluster to which you want to add the label. Replace env=production1 with the actual key-value pair that you want to add.
```
kubectl label managedclusters <clusterid> env=production1
```

Create a Policy object with the following code block. Set the clusterSelector parameter to the label that you added as the cluster selector.

Replace env: production1 with the key-value pair that you added.

apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
  name: cluster-test
  namespace: demo
type: topology
properties:
  clusterSelector:   
    env: production1     # The key-value pair that is used to select the cluster. If you want to select more than one cluster, add more key-value pairs below this key-value pair.


Parameter	Description
`type: topology`	A Policy object of the Topology type allows you to define the clusters to which applications are distributed. A Policy object of the Override type allows you to override the configurations of applications.
`properties: clusterSelector`	You can specify labels as cluster selectors. The specified labels are used to select clusters that are associated with the master instance.