Migrating Rancher to a New Cluster

If you are migrating Rancher to a new Kubernetes cluster, you don’t need to install Rancher on the new cluster first. If Rancher is restored to a new cluster with Rancher already installed, it can cause problems.

Prerequisites

These instructions assume that you have created a backup and already installed a new Kubernetes cluster where Rancher will be deployed. The backup is specific to the Rancher application and can only migrate the Rancher application.

Migrating Rancher to a New Cluster - 图1caution

You must use the same hostname that was set as the server URL in the original cluster. If you don’t, downstream clusters will show as unavailable in the cluster management page of the UI, and you won’t be able to click inside the cluster or on the cluster’s Explore button.

Rancher version must be v2.5.0 and up

Rancher can be installed on any Kubernetes cluster, including hosted Kubernetes clusters such as Amazon EKS clusters. For help installing Kubernetes, refer to the documentation of the Kubernetes distribution. A Rancher-created Kubernetes distributions such as, but not limited to, RKE or K3s may also be used.

Since Rancher can be installed on any Kubernetes cluster, you can use this backup and restore method to migrate Rancher from one Kubernetes cluster to any other Kubernetes cluster. This method only migrates Rancher-related resources and won’t affect other applications on the cluster. Refer to the support matrix to identify which Kubernetes cluster types and versions are supported for your Rancher version.

1. Install the rancher-backup Helm chart

Install the rancher-backup chart:

  1. Add the Helm repository:

    1. helm repo add rancher-charts https://charts.rancher.io
    2. helm repo update

  2. Set a CHART_VERSION variable, selecting a rancher-backup chart version compatible with your version of Rancher. See the support matrix, within the Rancher Apps / Cluster Tools section, to see which rancher-backup versions are supported:

    1. CHART_VERSION=<chart-version>

  3. Install the charts:

    1. helm install rancher-backup-crd rancher-charts/rancher-backup-crd -n cattle-resources-system --create-namespace --version $CHART_VERSION
    2. helm install rancher-backup rancher-charts/rancher-backup -n cattle-resources-system --version $CHART_VERSION

    Migrating Rancher to a New Cluster - 图2note

    The above assumes an environment with outbound connectivity to Docker Hub.

    For an air-gapped environment, use the following Helm value to pull the backup-restore-operator image from your private registry when you install the rancher-backup Helm chart.

    1. --set image.repository <registry>/rancher/backup-restore-operator

2. Restore from backup using a Restore custom resource

  1. When using S3 object storage as the backup source for a restore that requires credentials, create a Secret object in this cluster to add the S3 credentials. The secret data must have two keys - accessKey, and secretKey, that contain the S3 credentials.

    The secret can be created in any namespace, this example uses the default namespace.

    1. kubectl create secret generic s3-creds \
    2.   --from-literal=accessKey=<access key> \
    3.   --from-literal=secretKey=<secret key>

    Migrating Rancher to a New Cluster - 图3note

    Add your access key and secret key as values for accessKey and secretKey in the command above.

  2. Create a Restore object:

    During a migration, prune must be set to false. See the example below:

    1. # restore-migration.yaml
    2. apiVersion: resources.cattle.io/v1
    3. kind: Restore
    4. metadata:
    5.   name: restore-migration
    6. spec:
    7.   backupFilename: backup-b0450532-cee1-4aa1-a881-f5f48a007b1c-2020-09-15T07-27-09Z.tar.gz
    8.   prune: false
    9.   encryptionConfigSecretName: encryptionconfig
    10.   storageLocation:
    11.     s3:
    12.       credentialSecretName: s3-creds
    13.       credentialSecretNamespace: default
    14.       bucketName: backup-test
    15.       folder: ecm1
    16.       region: us-west-2
    17.       endpoint: s3.us-west-2.amazonaws.com

    Migrating Rancher to a New Cluster - 图4Important

    The field encryptionConfigSecretName should be used only if your backup was created with encryption enabled.

    If this applies, provide the name of the Secret object containing the encryption config file. If you only have the encryption config file, but don’t have the secret created in this cluster, use the following steps to create the secret:

    1. Create an encryption configuration file

    2. The command below uses a file named encryption-provider-config.yaml, with the --from-file flag. Run the below once the EncryptionConfiguration is saved in a file called encryption-provider-config.yaml:

      1. kubectl create secret generic encryptionconfig \
      2.   --from-file=./encryption-provider-config.yaml \
      3.   -n cattle-resources-system

  3. Apply the manifest, and monitor the Restore status:

    1. Apply the Restore object resource:

      1. kubectl apply -f restore-migration.yaml

    2. Watch the Restore status:

      1. kubectl get restore

    3. Watch the restoration logs:

      1. kubectl logs -n cattle-resources-system --tail 100 -f -l app.kubernetes.io/instance=rancher-backup

    4. Once the Restore resource has the status Completed, you can continue the cert-manager and Rancher installation.

3. Install cert-manager

Follow the steps to install cert-manager in the documentation about installing cert-manager on Kubernetes.

4. Bring up Rancher with Helm

Use the same version of Helm to install Rancher, that was used on the first cluster.

For Kubernetes v1.25 or later, set global.cattle.psp.enabled to false when using Rancher v2.7.2-v2.7.4. This is not necessary for Rancher v2.7.5 and above, but you can still manually set the option if you choose.

  1. helm install rancher rancher-latest/rancher \
  2.   --namespace cattle-system \
  3.   --set hostname=<same hostname as the server URL from the first Rancher server> \
  4.   --version x.y.z

Migrating Rancher to a New Cluster - 图5note

If the original Rancher environment is running, you can collect the current values with a kubeconfig for the original environment:

  1. helm get values rancher -n cattle-system -o yaml > rancher-values.yaml

These values can be reused using the rancher-values.yaml file. Be sure to switch the kubeconfig to the new Rancher environment.

  1. helm install rancher rancher-latest/rancher -n cattle-system -f rancher-values.yaml --version x.y.z

5. Redirect Traffic to the New Cluster

After migration completes, update your DNS records and any load balancers, so that traffic is routed correctly to the migrated cluster. Remember that you must use the same hostname that was set as the server URL in the original cluster.

Full instructions on how to redirect traffic to the migrated cluster differ based on your specific environment. Refer to your hosting provider’s documentation for more details.