Bazel Bzlmod and Dependency Management Training

Master Bazel's modern dependency management system with Bzlmod, the MODULE.bazel-based approach that replaces the legacy WORKSPACE file. This 2-day training covers the Bazel Central Registry, custom registries, version resolution algorithms, and practical migration strategies for existing WORKSPACE-based projects preparing for Bazel 7+ and the WORKSPACE removal in Bazel 9.

Training Details

Duration	2 days (16 hours)
Level	Intermediate
Delivery	In-person, Live online, Hybrid
Certification	N/A

Who Is This For?

• Build engineers managing Bazel dependency infrastructure
• Platform engineers migrating from WORKSPACE to Bzlmod
• Software engineers working with external dependencies in Bazel
• Tech leads planning Bazel version upgrades (Bazel 7+)
• DevOps engineers maintaining internal Bazel registries

Learning Outcomes

After completing this training, participants will be able to:

• Write MODULE.bazel files with bazel_dep, module extensions, and use_repo declarations
• Navigate and publish modules to the Bazel Central Registry
• Set up and maintain custom Bazel registries for internal modules
• Migrate existing WORKSPACE files to Bzlmod incrementally
• Configure language-specific dependency management (Maven, pip, Go modules)
• Resolve version conflicts using overrides, compatibility_level, and yanked versions

Detailed Agenda

Day 1: Bzlmod Architecture and Registry System

Module 1: Bzlmod Concepts and Motivation

• WORKSPACE limitations: no transitive dependency management, load order sensitivity
• Bzlmod design goals: reproducible, diamond-safe dependency resolution
• MODULE.bazel syntax: module(), bazel_dep(), use_repo(), use_extension()
• Module versions, compatibility_level, and semantic versioning
• Bzlmod resolution algorithm: Minimal Version Selection (MVS)
• Hands-on: Create a MODULE.bazel from scratch, declare dependencies, explore the resolved dependency graph

Module 2: MODULE.bazel Syntax Deep Dive

• module() declaration: name, version, compatibility_level, repo_name
• bazel_dep() attributes: version, max_compatibility_level, dev_dependency
• Module extensions: use_extension(), tag classes, extension implementation
• use_repo() for importing repositories from extensions
• register_toolchains() and register_execution_platforms() in Bzlmod
• Hands-on: Write a MODULE.bazel with multiple dependencies, module extensions, and toolchain registrations

Module 3: Registry System and Bazel Central Registry

• Bazel Central Registry (BCR) structure: modules/, metadata, source.json, patches
• Browsing and searching the BCR at registry.bazel.build
• Custom registries: local path registries, Git-based registries, HTTP archive registries
• Registry selection priority: --registry flag, .bazelrc configuration
• Publishing to the BCR: module submission process, presubmit.yml
• Hands-on: Set up a local file-based registry, publish a module, configure registry priority

Module 4: WORKSPACE to Bzlmod Migration

• Bzlmod and WORKSPACE coexistence: --enable_workspace flag (Bazel 7 default off, Bazel 8 deprecated)
• WORKSPACE removal timeline: Bazel 9 removes WORKSPACE support entirely
• Migration strategy: incremental dependency migration, hybrid mode
• Identifying WORKSPACE deps: http_archive, git_repository, maven_install mappings
• Common migration pitfalls: macro expansion, bind() removal, managed_directories removal
• Hands-on: Migrate a real-world WORKSPACE file to MODULE.bazel incrementally, verify build equivalence

Day 2: Language-Specific Dependencies and Conflict Resolution

Module 5: Java and Maven Dependencies

• rules_jvm_external in Bzlmod: maven.install tag class
• Artifact pinning with maven_install.json lock file
• Excluding transitive dependencies, forcing versions
• Maven BOM support and dependency management
• Private Maven repository authentication
• Hands-on: Configure Maven dependencies via Bzlmod, pin versions, resolve transitive conflicts

Module 6: Python and pip Dependencies

• pip.parse in Bzlmod: requirements_lock, python_interpreter_target
• Per-platform requirements files with requirements_linux, requirements_darwin
• Wheel-only installs and sdist compilation requirements
• Hub repositories and pip_parse multi-version support
• Vendoring Python dependencies for hermetic builds
• Hands-on: Set up Python dependencies with pip.parse, handle platform-specific packages, create lock files

Module 7: Go and Gazelle Dependencies

• go_deps module extension: from_file with go.mod
• Gazelle integration with Bzlmod: gazelle:update, gazelle:resolve
• Go module proxy configuration and GOPROXY settings
• Replacing Go modules with local paths using overrides
• Managing Go toolchain versions with rules_go Bzlmod extension
• Hands-on: Configure Go dependencies from go.mod via Bzlmod, run Gazelle, manage Go toolchain versions

Module 8: Version Conflict Resolution and Capstone

• Minimal Version Selection (MVS) in practice: version upgrades and downgrades
• single_version_override: forcing a specific version globally
• multiple_version_override: allowing diamond dependencies with different versions
• archive_override, git_override, local_path_override for development
• Yanked versions: marking broken releases, --allow_yanked_versions
• bazel mod graph, bazel mod deps, bazel mod explain for dependency debugging
• Hands-on: Capstone project — migrate a multi-language project from WORKSPACE to Bzlmod, set up a custom registry for internal modules, resolve version conflicts, and verify hermetic builds

Prerequisites

• Bazel Fundamentals training or equivalent hands-on experience with Bazel
• Experience with WORKSPACE files and external dependency management
• Familiarity with at least one language-specific package manager (Maven, pip, Go modules)
• Understanding of semantic versioning and dependency resolution concepts

Delivery Formats

Format	Description
In-Person	On-site at your company's location, hands-on with direct interaction
Live Online	Interactive virtual sessions with screen sharing and real-time labs
Hybrid	Combination of on-site and remote sessions, flexible scheduling

All formats include hands-on labs, course materials, and post-training support.