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feat: implement cluster joining for server and worker nodes

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Different options get applied to each depending on what is needed for the role.

This also updates how we initialize the cluster to better support how metrics exposure and cross-server networking.
This commit is contained in:
Jose Diaz-Gonzalez
2024-01-20 04:58:02 -05:00
parent af3009f0da
commit 69e9511666
7 changed files with 593 additions and 29 deletions
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25
docs/deployment/schedulers/k3s.md
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@@ -145,10 +145,31 @@ In some cases, Dokku must be setup from scratch and joined to an existing cluste
dokku scheduler-k3s:set --global token topsecret:server:token
```
Next, run the `scheduler-k3s:join-cluster` command. This command takes a single server node in the cluster, will SSH onto the specified server, retrieve the kubeconfig, and then configure kubectl on the Dokku node to speak with the specified k3s cluster. Dokku will also periodically retrieve all server nodes in the cluster so that server nodes can be safely replaced as needed.
Next, run the `scheduler-k3s:cluster-add` command. This command takes a single server node in the cluster, will SSH onto the specified server, retrieve the kubeconfig, and then configure kubectl on the Dokku node to speak with the specified k3s cluster.
> [!TODO]
> TODO: Dokku will also periodically retrieve all server nodes in the cluster so that server nodes can be safely replaced as needed.
```shell
dokku scheduler-k3s:join-cluster root@server-1.example.com
dokku scheduler-k3s:cluster-add ssh://root@worker-1.example.com
```
If the server isn't in the `known_hosts` file, the connection will fail. This can be bypassed by setting the `--insecure-allow-unknown-hosts` flag:
```shell
dokku scheduler-k3s:cluster-add --insecure-allow-unknown-hosts ssh://root@worker-1.example.com
```
New server nodes are added as worker nodes which run application workloads but do not otherwise participate in managing the cluster. For high availability, new server nodes can be added to the cluster by specifying the `--role` flag:
```shell
dokku scheduler-kes:cluster-add --role server ssh://root@cluster-1.example.com
```
Server nodes allow any workloads to be scheduled on them by default, in addition to the control-plane, etcd, and the scheduler itself. To avoid app workloads being scheduled on your control-plane, use the `--taint-scheduling` flag:
```shell
dokku scheduler-kes:cluster-add --role server --taint-scheduling ssh://root@cluster-1.example.com
```
### Using kubectl remotely