docs: add section about multi-master setups

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iwilltry42 2020-05-11 08:44:57 +02:00
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# Creating multi-master clusters
!!! note "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.
```bash
k3d create cluster multimaser --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:
```bash
k3d create node newmaster --cluster multimaster --role master
```
!!! note "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.