If you have a cluster in Rancher that you want to use as a template for creating similar clusters, you can use Rancher CLI to clone the cluster’s configuration, edit it, and then use it to quickly launch the cloned cluster.

Caveats

  • Only cluster types that interact with cloud hosts over API can be cloned. Duplication of imported clusters and custom clusters provisioned using Docker machine is not supported.

    Cluster Type Cloneable?
    Hosted Kubernetes Providers
    Nodes Hosted by Infrastructure Provider
    Custom Cluster
    Imported Cluster
  • During the process of duplicating a cluster, you will edit a config file full of cluster settings. However, we recommend editing only values explicitly listed in this document, as cluster duplication is designed for simple cluster copying, not wide scale configuration changes. Editing other values may invalidate the config file, which will lead to cluster deployment failure.

Prerequisites

Download and install Rancher CLI. Remember to create an API bearer token if necessary.

1. Export Cluster Config

Begin by using Rancher CLI to export the configuration for the cluster that you want to clone.

  1. Open Terminal and change your directory to the location of the Rancher CLI binary, rancher.

  2. Enter the following command to list the clusters managed by Rancher.

    ./rancher cluster ls
    
  3. Find the cluster that you want to clone, and copy either its resource ID or NAME to your clipboard. From this point on, we’ll refer to the resource ID or NAME as <RESOURCE_ID>, which is used as a placeholder in the next step.

  4. Enter the following command to export the configuration for your cluster.

    ./rancher clusters export <RESOURCE_ID>
    

    Step Result: The YAML for a cloned cluster prints to Terminal.

  5. Copy the YAML to your clipboard and paste it in a new file. Save the file as cluster-template.yml (or any other name, as long as it has a .yml extension).

2. Modify Cluster Config

Use your favorite text editor to modify the cluster configuration in cluster-template.yml for your cloned cluster.

  1. Open cluster-template.yml (or whatever you named your config) in your favorite text editor.

    Warning: Only edit the cluster config values explicitly called out below. Many of the values listed in this file are used to provision your cloned cluster, and editing their values may break the provisioning process.

  2. As depicted in one of the examples below, at the <CLUSTER_NAME> placeholder, replace your original cluster’s name with a unique name (<CLUSTER_NAME>). If your cloned cluster has a duplicate name, the cluster will not provision successfully.

    Version: v3
    clusters:
        <CLUSTER_NAME>: # ENTER UNIQUE NAME
        dockerRootDir: /var/lib/docker
        enableNetworkPolicy: false
        googleKubernetesEngineConfig:
          credential: |-
            {
              "type": "service_account",
              "project_id": "gke-cluster-221300",
              "private_key_id": "1d210afae352bc298bde1b3e680ec0c8b22cdd61"
    Version: v3
    clusters:
        <CLUSTER_NAME>: # ENTER UNIQUE NAME
        amazonElasticContainerServiceConfig:
            accessKey: 00000000000000000000
            associateWorkerNodePublicIp: true
            instanceType: t2.medium
            maximumNodes: 3
            minimumNodes: 1
            region: us-west-2
            secretKey: 0000000000000000000000000000000000000000
        dockerRootDir: /var/lib/docker
        enableNetworkPolicy: false
    Version: v3
    clusters:
        <CLUSTER_NAME>: # ENTER UNIQUE NAME
        azureKubernetesServiceConfig:
          adminUsername: azureuser
          agentPoolName: rancher
          agentVmSize: Standard_D5_v2
          clientId: 00000000-0000-0000-0000-000000000000
          clientSecret: 00000000000000000000000000000000000000000000
          count: 3
          kubernetesVersion: 1.11.2
          location: westus
          osDiskSizeGb: 100
          resourceGroup: docker-machine
          sshPublicKeyContents: ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDJc2kDExgRaDLD
    Version: v3
    clusters:
        <CLUSTER_NAME>: # ENTER UNIQUE NAME
        dockerRootDir: /var/lib/docker
        enableNetworkPolicy: false
        rancherKubernetesEngineConfig:
          addonJobTimeout: 30
          authentication:
            strategy: x509
          authorization: {}
          bastionHost: {}
          cloudProvider: {}
          ignoreDockerVersion: true

  3. Nodes Hosted by Infrastructure Provider Only: For each nodePools section, replace the original nodepool name with a unique name at the <NODEPOOL_NAME> placeholder. If your cloned cluster has a duplicate nodepool name, the cluster will not provision successfully.

    nodePools:
        <NODEPOOL_NAME>:
        clusterId: do
        controlPlane: true
        etcd: true
        hostnamePrefix: mark-do
        nodeTemplateId: do
        quantity: 1
        worker: true
  4. When you’re done, save and close the configuration.

3. Launch Cloned Cluster

Move cluster-template.yml into the same directory as the Rancher CLI binary. Then run this command:

./rancher up --file cluster-template.yml

Result: Your cloned cluster begins provisioning. Enter ./rancher cluster ls to confirm. You can also log into the Rancher UI and open the Global view to watch your provisioning cluster’s progress.