Description

Deploying via shell scripts is powerful in that it's incredibly flexible, but sometimes it's too cumbersome, ugly, or not functional enough. We need a higher-level construct, especially for deploys, that let's developers easily configure common deployment scenarios.

Proposal

• Introduce specific keywords for various deployment scenarios such as kubernetes, ideally through extensible plugins (#14178).
• The deploy plugin may run in the context of the GitLab rails server rather than the GitLab runner. There are various pros and cons to this.
  • Running in Rails allows access to deployment variables without having to expose them to the runners.
  • Running in Rails allows easier return of richer information than simple pass/fail exit code. e.g. return information needed for connecting a terminal to a container. (Runners could support this, but we'd have to extend the API)
  • Plugins running in Rails might be more approachable than writing in Go.
• Either way, the plugin would be able to directly connect services via API without needing scripts or CLIs.
• Plugins could be tightly tied to Services to provide the ability to store variables or otherwise configure deployment at a project level (#23859)
• Richer interactions could allow actions beyond simple deployment such as:
  • access a terminal that connects to running environments
  • smart monitoring of deployments
  • incremental/rolling deploys, canary deploys, blue/green deploys, traffic vectoring, etc.
  • simplifying closing environments
  • restart/pause/etc of environments
• The obvious downside is that this would be GitLab-specific, and up to us to maintain as things change.

review_app:
   kubernetes:
     pod: my/pod/file
   variables:
     MY_APP_DOMAIN: review-$DOMAIN.app.com
  environment:
    name: review/$APP

Links / references

• From #22864 (comment 16790373) and #23286 (closed)
• GitLab Runner plugins: #14178

/cc @ayufan