fix: disable metrics for per-WorkspaceType multicluster managers

[2mind]

Summary

targetcontroller.createMulticlusterManager() creates one multicluster manager per WorkspaceType, but never sets Metrics in the manager options. controller-runtime then falls back to its default bind address (:8080) for every one of them: the first manager claims the port, and each subsequent manager fails to start:

Failed to run multicluster manager  ctrlkey=root:account
error=failed to start metrics server: failed to create listener: listen tcp :8080: bind: address already in use

The WorkspaceType of the failed manager is then never initialized — its InitTargets are ignored until the pod restarts and happens to start with that target already known.

This disables the metrics server for the per-WorkspaceType managers (BindAddress: "0"). Only the main manager is supposed to serve metrics (--metrics-address, 127.0.0.1:8085 by default), and the secondary managers' metrics are not scraped from anywhere.

"Disable" rather than "one port per WorkspaceType" because the number of WorkspaceTypes is unbounded, while only a single metrics endpoint is actually served; if per-WorkspaceType metrics are ever wanted, they should be registered with a WorkspaceType label in the main registry instead.

Verification

• go build ./..., go vet ./internal/..., CGO_ENABLED=1 go test -tags unit ./... — pass.
• Reproduced on our kcp installation (kcp v0.32.x, kcp-operator 0.9.0, init-agent v0.4.0 with multicluster-provider v0.8.0): as soon as a second WorkspaceType appeared, its manager died with the error above and that WorkspaceType stayed uninitialized. The init-agent image we run in that installation carries this change (together with fix: wire event recorder into initializingworkspaces cluster multicluster-provider#117) and initializes all WorkspaceTypes in the cluster.

What Type of PR Is This?

/kind bug

Related Issue(s)

Fixes #26

Release Notes

Fix a metrics server port collision that prevented init-agent from initializing more than one WorkspaceType

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[kcp-ci-bot]

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[2mind]

/kind bug