Docker in CI/CD: The Patterns That Cut My Pipeline Time by 82%

My CI pipeline used to take 45 minutes. It now takes 8. The biggest wins came from Docker optimization — not faster hardware.

The Problem

Every CI run was:

1. Pull base image (2 min)
2. Install OS dependencies (5 min)
3. Install Python packages (8 min)
4. Install Node packages (6 min)
5. Build application (4 min)
6. Run tests (15 min)
7. Build production image (5 min)

Total: ~45 minutes. Developers stopped running the full pipeline. Bugs slipped through.

Fix 1: Multi-Stage Builds (45 → 30 min)

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