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Blue-Green Deploy

The deploy:test_prod CI job updates TEST_PROD with a blue-green rollout:

  1. Pull frontend and backend images by digest (from the publish stage).
  2. Build the proxy image and start the new color (e.g. backend_blue, frontend_blue).
  3. Wait for health checks (/health, /api/csrf-token) on the new color.
  4. Switch the proxy to the new color (nginx config updated via docker exec + reload).
  5. Stop the old color (e.g. backend_green, frontend_green).

No host-path bind mounts — On Windows CI, binding repo files into containers can fail ("mount directory onto file"). The frontend uses env-driven nginx config (NGINX_BACKEND_UPSTREAM); the proxy image is baked and config is injected with docker exec.

Related: Docker overview, Troubleshooting