Bazel Build Optimization
Production patterns for Bazel in large-scale monorepos.
When to Use This Skill
- Setting up Bazel for monorepos
- Configuring remote caching/execution
- Optimizing build times
- Writing custom Bazel rules
- Debugging build issues
- Migrating to Bazel
Core Concepts
1. Bazel Architecture
workspace/
├── WORKSPACE.bazel # External dependencies
├── .bazelrc # Build configurations
├── .bazelversion # Bazel version
├── BUILD.bazel # Root build file
├── apps/
│ └── web/
│ └── BUILD.bazel
├── libs/
│ └── utils/
│ └── BUILD.bazel
└── tools/
└── bazel/
└── rules/
2. Key Concepts
| Concept | Description |
|---|---|
| Target | Buildable unit (library, binary, test) |
| Package | Directory with BUILD file |
| Label | Target identifier //path/to:target |
| Rule | Defines how to build a target |
| Aspect | Cross-cutting build behavior |
Templates and detailed worked examples
Full template library and detailed worked examples live in references/details.md. Read that file when you need the concrete templates.
Best Practices
Do's
- Use fine-grained targets - Better caching
- Pin dependencies - Reproducible builds
- Enable remote caching - Share build artifacts
- Use visibility wisely - Enforce architecture
- Write BUILD files per directory - Standard convention
Don'ts
- Don't use glob for deps - Explicit is better
- Don't commit bazel-* dirs - Add to .gitignore
- Don't skip WORKSPACE setup - Foundation of build
- Don't ignore build warnings - Technical debt