Creating multi-master clusters

Important note

For the best results (and less unexpected issues), choose 1, 3, 5, … master nodes.

Embedded dqlite

Create a cluster with 3 master nodes using k3s’ embedded dqlite database. The first master to be created will use the --cluster-init flag and k3d will wait for it to be up and running before creating (and connecting) the other master nodes.

    k3d cluster create multimaster --masters 3

Adding master nodes to a running cluster

In theory (and also in practice in most cases), this is as easy as executing the following command:

    k3d node create newmaster --cluster multimaster --role master

There’s a trap!

If your cluster was initially created with only a single master node, then this will fail. That’s because the initial master node was not started with the --cluster-init flag and thus is not using the dqlite backend.

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Last update: July 14, 2020