[FF] Rollout ci_matrix_expressions gitlab_com_derisk

Summary

This issue is to roll out the ci_matrix_expressions feature that enables $[[ matrix.VARIABLE ]] syntax for dynamic job dependencies in CI matrix configurations.

Owners

• Most appropriate Slack channel: #g_pipeline-authoring
• Best individual to reach out to: @avielle

Expectations

What are we expecting to happen?

Users with matrix jobs using needs:parallel:matrix can use $[[ matrix.VAR ]] syntax to create 1:1 mappings between matrix jobs across stages without manual duplication.

What can go wrong and how would we detect it?

• Pipeline configuration parsing errors or failures
• Performance impact on CI config processing
• Monitor error rates in CI pipeline creation

Rollout Steps

Rollout on non-production environments

• Enable on staging and dev: /chatops run feature set ci_matrix_expressions true --dev --pre --staging --staging-ref

Specific rollout on production

• Enable for GitLab owned projects: /chatops run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss,gitlab-com/www-gitlab-com ci_matrix_expressions true

Global rollout on production

• Enable globally: /chatops run feature set ci_matrix_expressions true

Release the feature

• Create a merge request to remove the ci_matrix_expressions feature flag:
• Once cleanup MR is deployed, delete the feature flag: /chatops run feature delete ci_matrix_expressions --dev --pre --staging --staging-ref --production
• Close this rollout issue

Rollback Steps

• Disable globally: /chatops run feature set ci_matrix_expressions false
• Delete feature flag from all environments: /chatops run feature delete ci_matrix_expressions --dev --pre --staging --staging-ref --production