Bazel External Deps Roadmap

Last verified: 2018-07-17 (Update history)

Point of contact: dslomov

Roadmap for improving external dependencies support and integration with package managers and other build systems in Bazel.

Goal

External dependencies work fall into three broad categories:

1. General improvements for WORKSPACE support in Bazel (see External Repositories: The Future for general background and discussion).

2. Allowing Bazel project to depend on other projects built with a different build tool and/or available through a package manager.
   • bazel-deps is one tool that provide that support.
   • A good analysis of challenges with C++ dependencies has been done by Envoy project.
3. Allowing other build systems to depend on Bazel project.
   • Generally this includes features such as
     • plugins for other build systems invoking Bazel
     • publishing Bazel-built artifacts so that they can be used by other build systems
     • generating project files for other build systems
   • The full set of features needed for this is currently forming. (We welcome your input on bazel-discuss@)

2018 Q2

1. General improvements for WORKSPACE support in Bazel
   • Implement diamond splitting for external dependencies. DONE
   • Prototype support for WORKSPACE.resolved
     • Blog post
2. Bazel depends on 3rd-party
   • Exeperiments in rules_foreign_cc

2018 Q3

1. General improvements for WORKSPACE support in Bazel
   • Document curent state and best practices for BUILD files that can be used both as main and external repository, decide on whether the change to exec root layout is needed
   • Implement WORKSPACE/WORKSPACE.resolved split, so that users can easily upgrade and share their dependencies in a controlled and well-defined way
   • Technical plan for recursive workspaces: convenient way for users to manage transitive dependencies
2. Bazel depends on 3rd-party
   • Provide rules for cmake and other C++ build systems
     • Validation: Envoy is able to switch to these rules for their cmake dependecies.
   • Integrate bazel-deps into WORKSPACE.resolved so that users don’t have to run it as a separate tool
   • Technical plan for PIP support

2018 Q4

• Technical plan for better support of WORKSPACE.configured (tentative)
• Technical plan for improvements of repository rule APIs and semantics (no restarts? action graphs?)