Module 10 Lesson 5: Documentation & Handoff

The most successful pipeline is one that works even when you are on vacation. If you are the only one who knows how to fix the .gitlab-ci.yml, you aren't an "Engineer"—you're a "Single Point of Failure."

1. Documenting the "Why"

Inside your YAML file, use Comments to explain the non-obvious parts.

Bad: # Run tests
Good: # We use --no-sandbox here because the GitLab Shared Runner lacks Chrome permissions.

2. The Project README

Every repository should have a "CI/CD Section" in its README that answers:

What variables are required? (List DB_PASSWORD, STRIPE_KEY, etc. - but not the values!).
How do I run the build locally?
How do I "Force" a bypass if a test is flaky?

3. The "Handoff" Checklist

When you finish a new pipeline, ask a teammate to try and "Break" it.

Can they find the logs?
Can they understand the "Orange" warning status?
If they delete a variable, does the error message in the console tell them exactly what is missing?

4. Visualizing with Diagrams

For complex multi-project pipelines (Module 4), a simple "Mermaid" diagram in your documentation can save 10 hours of explanation.

graph LR
    Trigger[Dev Push] --> Pipeline[CI Pipeline]
    Pipeline -->|Success| Deploy[Production]
    Pipeline -->|Failure| Alert[Slack Channel]

Exercise: The Legacy Audit

Go to an old project you built. If you look at the .gitlab-ci.yml now, can you remember exactly why you added every line?
Add a "CI/CD Documentation" section to your current project's README.
List 5 "Hidden" variables that a new developer on your team would need to set up to get the pipeline working.
Search: What is "GitLab Pages"? How can it be used to host your technical documentation and test reports automatically?

Summary

You have completed Module 10: CI/CD Best Practices. You are now not just a "Scripter," but a "DevOps Architect." You build systems that are DRY, Modular, Resilient, and well-documented.

Next Module: The Real World: Module 11: Real-World Case Studies.