Support hostNetwork on the server StatefulSet

[kopiczko]

Is your feature request related to a problem? Please describe.
We'd like to reuse K8s API etcd as a backend for the vault instance running inside the cluster. This is CAPI cluster where etcd pod runs in the host network bound to localhost. This etcd pod doesn't expose any ports. There isn't really way to expose this port cleanly because it's created with upstream controllers. We'd like to run vault server in the host network to make it possible to reach the etcd.

Describe the solution you'd like
Add server.hostNetwork setting.

Describe alternatives you've considered
We were thinking about exposing etcd with a proxy but that may make it complicated with the certificates.

Additional context
N/A. I'm happy to provide a PR if this is something you'd accept.

[dealweb723]

I'm encountering a similar request as this. Any updates?

[kopiczko]

@dealweb723 what we are doing right now is:

...

  tolerations:
    - key: "node-role.kubernetes.io/master"
      operator: "Exists"

...

    config: |
      backend "etcd" {
        address = "https://HOST_IP:2379"
        
        ...

      }

...

The downside here is that it has to run on the control plane.