Keepalived and IPA-downloader support as plugins?

[dtantsur]

Hi folks,

I've been thinking about connecting keepalived support to IrSO (without it, metal3-dev-env won't work). Similarly to IronicDatabase, we could just create a Keepalived resource. Not similarly to IronicDatabase, keepalived has to be deployed into the same Deployment as Ironic (but not on HA, I guess?).

On top of that, I'm thinking how to enable downstream modifications. For example, OpenShift does not use Keepalived, it injects something else into the pod.

[dtantsur]

Option 1: hardcode Keepalived support, let OpenShift fork the project. As an OpenShift developer, I'd hate this.

[dtantsur]

Option 2: some sort of CR-level plugins? Imagine, I create an Ironic this way:

---
apiVersion: metal3.io/v1alpha1
kind: Keepalived
metadata:
  name: ironic-sample
spec: {}
---
apiVersion: metal3.io/v1alpha1
kind: Ironic
metadata:
  name: ironic-sample
spec:
  networking:
    ipAddress: 172.0.2.2
    ipManagerRef:
      apiGroup: metal3.io/v1alpha1
      kind: Keepalived
      name: ironic-sample

Then I expect the Keepalived controller to... modify the Deployment? Somehow in a way that the Ironic controller don't override?

This is not a well thought solution, but I'd be curious to hear feedback.

[dtantsur]

Option 3: add explicit support for Keepalived, use #75 (which I think is useful regardless) for downstreams.

[tuminoid]

I think I agree. Option 1 is not great, option 2 has implementation issues.

[elfosardo]

I do think this is the best option too

[lentzi90]

I agree. This is a common pattern also in the whole ecosystem. Sooner or later there will be a user who wants to override something, add their own sidecar, etc. and then this is practically the only way to accommodate all use-cases.

[lentzi90]

To back my claim that this is a common pattern, I link to the cert-manager and CAPI operator configuration docs:

• cert-manager allows arbitrary volumes for example: https://artifacthub.io/packages/helm/cert-manager/cert-manager#volumes-~-array
• CAPI operator allows arbitrary containers and more: https://github.com/kubernetes-sigs/cluster-api-operator/blob/main/docs/README.md#provider-spec

[dtantsur]

Thanks all! Here goes: #77 (no extra configuration needed so I did not end up creating a new resource in the end).