[Feature flag] Rollout of `vue3_migrate_clusters`

Summary

Roll out the feature currently behind the vue3_migrate_clusters feature flag.

DRI: @mrincon
Team Slack channel: TBD

Note

Process and guidance live in the docs — this issue is just the commands and a place to track the rollout. "Rolling out" means incrementally enabling the flag on GitLab.com to validate stability — it is not the same as releasing the feature, which happens when the flag is removed. Feature flag controls · Feature flag lifecycle

What could go wrong?

Blast radius is the Kubernetes cluster pages. No data is written by the flag, so there is no data-loss risk.

Most of these pages sit behind the default-off certificate_based_clusters ops flag, so few users reach them. The exception is the agent tab on */clusters/index, which always renders and is linked from three sidebars. Treat that page as the real blast radius.

Watch for:

~/clusters/clusters_bundle.js:104 mounts with the raw new Vue({ el, ... }) constructor, so its root carries no data-gitlab-vue3-app marker. A silent fallback to Vue 2 there is invisible. Check it by hand.
The cluster feature specs never stub certificate_based_clusters, so a green suite does not prove the deprecated pages work.

Rollout

Run all production /chatops in #production and cross-post the results to TBD. Background: incremental rollout process, feature actors.

Non-production

/chatops gitlab run feature set vue3_migrate_clusters 50 --actors --dev --pre --staging --staging-ref
/chatops gitlab run feature set vue3_migrate_clusters true --dev --pre --staging --staging-ref

Production — percentage rollout (wait ≥15 min between steps, watch dashboards):

/chatops gitlab run feature set vue3_migrate_clusters <percentage> --actors

Or target specific actors instead:

/chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss vue3_migrate_clusters true
/chatops gitlab run feature set --group=gitlab-org,gitlab-com vue3_migrate_clusters true
/chatops gitlab run feature set --user=mrincon vue3_migrate_clusters true

Before global rollout

Confirm the relevant gotchas before going to 100% — see enabling a feature for GitLab.com:

Docs + version history updated
Breaking changes announced, if any
Change management issue opened, if required
External API consumers handled with a fail-open mechanism, if applicable

Cleanup

Remove the flag once deemed stable — see cleaning up. Track it here, or open a follow-up Feature Flag Cleanup issue. Remove the flag and its YAML definition from the codebase, then:

/chatops gitlab run release check <merge-request-url> <milestone>
/chatops gitlab run feature delete vue3_migrate_clusters --dev --pre --staging --staging-ref --production

Rollback

/chatops gitlab run feature set vue3_migrate_clusters false                                         # production
/chatops gitlab run feature set vue3_migrate_clusters false --dev --pre --staging --staging-ref     # non-production
/chatops gitlab run feature delete vue3_migrate_clusters --dev --pre --staging --staging-ref --production  # remove entirely

[Feature flag] Rollout of vue3_migrate_clusters