Describe the best pipeline for deployment to production: what stages, what conditions?

The best pipeline for deployment to production usually includes the following stages:

1. Build — compiling code, installing dependencies, building artifacts.
2. Testing — running unit tests, integration tests, static code analysis.
3. Staging/Pre-prod — deploying to a test or intermediate server where functionality can be verified in conditions close to production.
4. Code review and approval — manual or automated confirmation of quality and readiness for release.
5. Deploy to production — deploying to the production environment.
6. Monitoring and rollback — observing metrics and logs, with the ability to quickly rollback if issues arise.

Conditions and best practices:

• Automate all stages to eliminate human factors.
• Use feature flags for gradual rollout of new features.
• Canary or blue-green deployment to minimize risks.
• Have automated tests with high coverage.
• Clear criteria for transitioning between stages (e.g., all tests must pass successfully).

Example of a simple YAML pipeline for CI/CD:

stages:
  - build
  - test
  - deploy_staging
  - approval
  - deploy_prod

build:
  stage: build
  script:
    - npm install
    - npm run build

test:
  stage: test
  script:
    - npm test

deploy_staging:
  stage: deploy_staging
  script:
    - deploy.sh staging

approval:
  stage: approval
  when: manual

deploy_prod:
  stage: deploy_prod
  script:
    - deploy.sh production
  when: on_success
  needs:
    - approval

This pipeline ensures quality control and release safety.