Replace Docker-based builds with Nix flakes for reproducible builds.
Changes:
- Use nixos/nix:latest image with `nix` tag requirement
- Build Docker image with `nix build .#dockerImage`
- Add optional Cachix integration for binary caching
- Load image with `docker load < result`
- Keep existing deploy stage unchanged
Benefits:
- Reproducible builds across all environments
- Binary caching via Cachix (faster subsequent builds)
- All dependencies pinned in flake.lock
- Image size similar to Docker builds (~507 MB compressed)
Requirements:
- GitLab Runner with Nix installed and `nix` tag
- Docker socket mounted for loading/pushing images
- Optional: CACHIX_AUTH_TOKEN for binary caching
See docs/gitlab-runner-nix-setup.md for runner setup instructions.
The old Docker-based config is available in git history if rollback needed.
- Update GitLab CI deploy job to set DEPLOY_TIMESTAMP when deploying
- Use 'kubectl set env' to update all pods with same timestamp
- Change deployment.yaml to use static placeholder value
- Update documentation to explain GitLab CI timestamp approach
This ensures all pods show the same deployment time, regardless of:
- Which pod handles the request (with replicas=2)
- When individual pods were created or restarted
- Pod restarts from crashes or rolling updates
The timestamp now represents when the deployment was initiated by GitLab CI,
not when individual pods were created.
- Migrations now run in Application.start/2 before starting services
- Ecto's advisory locks prevent concurrent migrations in clustered setup
- Simplified deployment - no separate migration job needed
- Removed migrate-job.yaml manifest
- Create Kubernetes Job to run migrations before deployment
- Update GitLab CI to execute migration job and wait for completion
- Ensures migrations run once per deployment in clustered environment
- Migration job uses PostgreSQL advisory locks to prevent race conditions
