How to specify arguments multiple times with different values in RKE

This document (000021231) is provided subject to the disclaimer at the end of this document.

Environment

Rancher > v2.6.7 and RKE > v1.3.13

Situation

It may be required to specify extra arguments multiple times with different values for RKE components. This can be accomplished using the field extra_args_array within the cluster YAML configuration.

Note:
The example below covers adding the service-account-key-file flag[1][2] to the kube-apiserver of a downstream RKE cluster. The specified file can contain multiple keys, and the flag can be specified multiple times with different files.

Resolution

Before you begin, ensure you have a recent healthy cluster snapshot[3] and add the certificate files to all the ControlPlane nodes in the cluster.

cp /etc/kubernetes/ssl/kube-apiserver-key.pem /etc/kubernetes/ssl/kube-apiserver-key2.pem
cp /etc/kubernetes/ssl/kube-apiserver-key.pem /etc/kubernetes/ssl/kube-apiserver-key3.pem

From the Rancher UI navigate to the Clusters Management page and locate the cluster you wish to make the change.
Click the three dots to the right of the UI for the cluster entry and then click Edit Config.
On the config page click the Edit as YAML option and add the arguments to the kube-apiserver similar below to the configuration.

   kube-api:
      extra_args_array:
        service-account-key-file:
          - /etc/kubernetes/ssl/kube-apiserver-key.pem
          - /etc/kubernetes/ssl/kube-apiserver-key2.pem
          - /etc/kubernetes/ssl/kube-apiserver-key3.pem

Save the configuration and allow the cluster to update. If the certificate files are not present on all the ControlPlane nodes the node the update will fail.

Note:
For clusters provisioned with the RKE binary, the extra_args_array configuration can be added to the cluster.yaml file for the required components.

Additional Information

References:

[1] https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
[2] https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/#serviceaccount-token-volume-projection
[3] https://ranchermanager.docs.rancher.com/how-to-guides/new-user-guides/backup-restore-and-disaster-recovery/restore-rancher-launched-kubernetes-clusters-from-backup#viewing-available-snapshots

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.