The Bazel APEX ruleset

Example

$ b build //path/to/module:com.android.module.apex --config=android

Code locations

The main entry point is the apex macro in //build/bazel/rules/apex/apex.bzl, which expands to the _apex rule implementation.

Related files in this directory include:

  • cc.bzl for the C/C++ specific aspect that traverses into native dependencies
  • toolchain.bzl for the host toolchain
  • transition.bzl for the configuration transition to add APEX-specific configuration to dependencies, like the APEX name and min sdk version.
  • apex_aab.bzl to repackage APEXes into multi-architecture Android app bundles and APK sets.
  • apex_info.bzl contains ApexInfo and ApexMkInfo providers. These form the main interface of an APEX target.
  • apex_key.bzl for the apex_key() rule
  • apex_test.bzl for Starlark analysis tests

The bp2build converter (ConvertWithBp2build) is located here.

The mixed build handler (ProcessBazelQueryResponse) is located here.

Major features

  • Build, compress, and sign APEX ext4 images and containers for all architectures/bitness
  • Supports outputs: .apex, .capex (compressed apex), .aab (Android app bundle), .apks (APK set)
  • Supports packaging prebuilts (e.g. tzdata), native shared libs, native binaries, sh_binary
  • Works with apex, override_apex and apex_test Soong module types
  • Supports AOSP and Google/Go APEX variants
  • Supports standalone/unbundled APEX builds (fast for development) with b and full platform build with m (preloaded on system)
  • Supports generating Mainline quality signals metadata files: required/provided libs, installed_files.txt
  • Internal mainline build scripts is capable of building multi-arch AABs/APKs in a single Bazel invocation

Detailed features

  • Bazel build settings/flags in //build/bazel/rules/apex/BUILD, like apexer_verbose and unsafe_disable_apex_allowed_deps_check
  • ABI stability for native deps
    • ABI stable stubs are marked as required, and not included within the APEX
    • non-ABI stable transitive deps are copied into the APEX
  • Supports testonly APEXes (converted from apex_test)
  • Supports default certificates with product config
  • Supports default file_contexts
  • Supports allowed_deps.txt validation
  • Supports apex_available validation
  • Supports min_sdk_version validation
  • Supports logging_parent, package_name, android_manifest, key.
  • Supports apex_manifest.pb conversion
  • Supports canned_fs_config generation
  • Supports file_contexts generation
  • Licensing: NOTICE.html.gz embedded in the APEX
  • All host tools are built from source by Bazel, or vendored prebuilts
  • All actions are fully sandboxed
  • Ability to build metadata files on the command line with --output_groups=<coverage_files,backing_libs,...>

Guardrails / others

  • --config=android is needed to build for the device. All APEX targets set target_compatible_with to android only - no host APEXes.
  • Comprehensive set of rule analysis tests for in apex_test.bzl
  • Example APEX in //build/bazel/examples/apex/...
  • Unit and integration tests in //build/bazel/{examples,tests,rules}/apex/... and //build/soong/tests/...

Known issues / gap analysis (non-exhaustive)

Upcoming features are based on Roboleaf module conversion priorities, like Java, Rust, DCLA and API fingerprinting support.

  • override_apex modules are converted to a regular apex with duplicated attributes. These are hidden by bp2build currently and will be cleaned up with macros in the future.
  • Correct product platform transitions for apex_aab to mainline_modules_* products
  • Java support
  • Rust support