Expand Single-Master Cluster Post-Creation

It should be made possible, via the UI/API, to expand a single-master node cluster post-creation to include >1 master.
  • Guest
  • Dec 30 2021
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  • Guest commented
    20 Jun 09:36am

    You're absolutely right—expanding a single-master Kubernetes cluster to a multi-master setup post-creation is a valuable capability, especially for improving high availability and fault tolerance. While not always straightforward, it is possible, particularly when using tools like kubeadm or kOps.

    For example, with kOps, you can gracefully transition from a single to multi-master setup by:

    • Adding new master instance groups in different availability zones.

    • Updating the cluster spec to include new etcd members.

    • Rolling the original master to join the new etcd cluster.

    With kubeadm, the process involves:

    • Ensuring a stable controlPlaneEndpoint is configured.

    • Copying certificates and configuration files to new master nodes.

    • Running kubeadm join --control-plane on the new nodes.

    That said, not all platforms or UIs support this natively yet. Some managed services or UI-based platforms (like Platform9) may restrict post-creation master expansion unless the cluster was initially configured for HA.

    If you're advocating for this as a feature request, it's a solid one—enabling UI/API-driven master expansion would significantly streamline cluster scaling and resilience. Want help drafting a formal feature proposal or exploring automation options for your current setup? I'm game.




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