[FCOS] openstack: workers don't join the cluster due to python scripts

[vrutkovs]

Openstack / oVirt are using a python script to find IPs: https://github.com/openshift/machine-config-operator/blob/fcos/templates/worker/00-worker/openstack/files/openstack-non-virtual-ip.yaml#L6

FCOS doesn't provide python (and most likely never will), so it needs to be rewritten

[LorbusChris]

cc @iamemilio

[cgwalters]

Probably best to track this as an MCO bug?

I think the fix is similar to okd-project/okd#38 - move the scripts into Go code executed in the machine-config-daemon binary.

[celebdor]

/assign celebdor

[cgwalters]

Today, we also ship /usr/libexec/machine-config-daemon in the host by default which comes from this repo. So, a useful pattern could be to add arbitrary subcommands to that binary.

Note though when submitting PRs to this repo, the binary in CI will not be updated - that currently only happens after code lands in master and goes through the main RHCOS build process.

[cgwalters]

Today, we also ship /usr/libexec/machine-config-daemon in the host by default which comes from this repo. So, a useful pattern could be to add arbitrary subcommands to that binary.

And to elaborate this is used today by e.g. this unit.

Note though when submitting PRs to this repo, the binary in CI will not be updated - that currently only happens after code lands in master and goes through the main RHCOS build process.

Hence today unfortunately one would have to "ratchet" a change here by landing the Go code in master, wait for it to propagate into an updated machine-os-content, then delete the other code and switch the calling code to use the new code.

[vrutkovs]

The PR can be tested on fcos branch - since FCOS doesn't ship MCD (and RHCOS shouldn't too really) it fetches the binary from the release payload and pivots early - thus MCD is always consistent across all nodes

[LorbusChris]

New approach:
Add a baremetal-runtimecfg-ubi8 image and use that to run the python scripts in a containerized way, exclusively in OKD.