Module 11 Lesson 5: Case Study: Global Monorepo

In this final study, we look at "OmniCorp," a company that keeps all its services (Auth, Payment, Search, Shipping, etc.) in One single Git repository.

1. The Challenge

• CI/CD Bloat: A standard pipeline would have 500+ jobs and take 4 hours.
• Merge Conflicts: 200 developers are pushing to the same repo every day.
• Network: Cloning the repo takes 10 minutes.

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2. The Solution: Dynamic Orchestration

1. Shallow Clones: Use GIT_DEPTH: 1 to only download the latest files.
2. Path-Based Triggers: Only run jobs for services that actually changed (Review Module 4, Lesson 2).
3. Parent/Child Pipelines: The master YAML is only 20 lines. It just "Dispatches" work to the sub-folders.

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3. The Blueprint (.gitlab-ci.yml)

# Master Parent Pipeline
include:
  - local: ci-configs/common.yml

dispatch-payment:
  trigger:
    include: services/payment/.gitlab-ci.yml
    strategy: depend
  rules:
    - changes: [services/payment/**/*]

dispatch-search:
  trigger:
    include: services/search/.gitlab-ci.yml
    strategy: depend
  rules:
    - changes: [services/search/**/*]

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4. The "Matrix" Optimization

For services that run on multiple OS versions (Windows, Linux, MacOS), the team uses the parallel: matrix keyword to generate 3 jobs from one single description. This ensures that "OmniCorp" apps work everywhere without writing 3 separate YAML files.

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Exercise: The Orchestrator's Puzzle

1. Service Alpha changed, triggering a Child pipeline. That child fails. Does the Parent pipeline show "Success" or "Failure"? (Review strategy: depend).
2. Why is the changes: rule the most important line in a Monorepo pipeline?
3. Imagine a developer changes a "Shared Library" in the /libs folder. How many child pipelines should be triggered? (How would you write that rule?)
4. Research: What is "Distributed Build Caching" (e.g., Bazel or Nx) and how does it integrate with GitLab CI?

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Summary

You have completed Module 11: Real-World Case Studies. You have seen how GitLab CI/CD adapts to every environment, from the small JS startup and the legacy PHP shop to the highly secure bank and the global enterprise monorepo.

Next Module: The final quest: Module 12: Capstone Project: Enterprise CI/CD Pipeline.