feat(controllers): add --controllers feature flag to enable/disable controllers per cluster

[igoramf]

Summary

• Each controller now has a unique ControllerName constant as its identifier
• New --controllers flag (and controllers.enabled Helm value) controls which controllers start at runtime — default ["*"] preserves existing behavior
• parseControllers validates the list at startup; unknown names are fatal errors
• Each of the 5 controllers/API is gated behind if enabled(...) in main.go
• Fixes the hub cluster crash caused by DecofileReconciler watching Revision.serving.knative.dev — set controllers.enabled: [decoredirect, operator-api] to disable decofile on hub

Usage

Hub cluster (infra_applications/hub/values.yaml):

controllers:
  enabled:
    - decoredirect
    - operator-api

All controllers (default):

controllers:
  enabled:
    - "*"

Invalid name → fatal error on startup:

ERROR  invalid --controllers flag  {"error": "unknown controller \"xpto\"; valid values: namespace, decofile, deco, decoredirect, operator-api"}

Test Plan

• make test passes
• helm template --set 'controllers.enabled[0]=decoredirect' --set 'controllers.enabled[1]=operator-api' renders --controllers=decoredirect,operator-api
• helm template (default) renders no --controllers arg
• Deploy to hub cluster with controllers.enabled: [decoredirect, operator-api] — operator starts without Knative crash

🤖 Generated with Claude Code

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Summary by cubic

Adds a --controllers runtime flag and controllers.enabled Helm value to turn controllers on/off per cluster. Default enables all; on the hub you can disable decofile to avoid the Knative Revision crash.

• New Features

  • --controllers (comma-separated names or "*"); unknown names fail fast with a clear error.
  • Controllers in cmd/main.go are gated via enabled(...); Valkey init/watchers and metrics run only when tenant is enabled; webhooks only when decofile is enabled.
  • Helm controllers.enabled; chart injects the flag only when not using ["*"]; parser tests added; hack/helm-generator injects the arg.
  • Build fix: Dockerfile and Makefile now build ./cmd to include new cmd/controllers.go.

• Refactors

  • Renamed NamespaceReconciler to TenantReconciler.
  • Added ControllerName constants for tenant, decofile, deco, decoredirect, and operator-api.

^{Written for commit 84ca738. Summary will update on new commits.}