Day 11: Crafting Multi-Stage Pipelines in GitLab CI/CD

Introduction

As we continue our journey into GitLab's CI/CD capabilities, today, we'll explore how to create and manage multi-stage pipelines. Multi-stage pipelines help streamline the development process by dividing it into organized, sequential stages, ensuring smoother and error-free deployments.

Why Multi-Stage Pipelines?

Multi-stage pipelines let you separate different parts of your CI/CD process. This means if a job fails, it won’t affect the subsequent jobs unless they're dependent on the failed one. It improves clarity, efficiency, and accuracy.

A Basic Multi-Stage Pipeline

In GitLab, the stages of a pipeline are defined in the .gitlab-ci.yml file. Here's a basic example:

stages:
  - build
  - test
  - deploy

build_job:
  stage: build
  script:
    - echo "Building the project..."

test_job:
  stage: test
  script:
    - echo "Testing the project..."

deploy_job:
  stage: deploy
  script:
    - echo "Deploying to production..."

In this setup, the pipeline will first build the project, then test it, and if all goes well, deploy it.

Adding More Stages and Jobs

Let's add an additional stage for code-review.

stages:
  - build
  - test
  - code-review
  - deploy

# ... [previous jobs]

code_review:
  stage: code-review
  script:
    - echo "Running automated code review tools..."
    # Insert code review scripts or tools here.

Sequential and Parallel Jobs

Within a stage, jobs run in parallel by default. If you have multiple jobs under the test stage, they will run simultaneously, speeding up your pipeline.

stages:
  - test

unit_tests:
  stage: test
  script:
    - echo "Running unit tests..."

integration_tests:
  stage: test
  script:
    - echo "Running integration tests..."

Both unit_tests and integration_tests will run in parallel since they are part of the same test stage.

Dependencies Between Jobs

GitLab provides the dependencies keyword to specify which jobs another job depends on. This is useful if you want a job in a later stage to use artifacts from an earlier stage.

# ... [previous stages and jobs]

deploy_staging:
  stage: deploy
  script:
    - deploy_to_staging.sh
  dependencies:
    - build_job
    - test_job

Conclusion

Mastering multi-stage pipelines in GitLab can revolutionize your CI/CD process, making it more structured and efficient. By clearly segmenting different parts of the development cycle, you can ensure that each phase is completed thoroughly before moving to the next. Tomorrow, we'll dive deeper into parallel and matrix builds in GitLab, which can further optimize and speed up your pipelines.

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