Bazel Documents

This is an index of all documents for Bazel.

There are two kinds:

• Design docs that are subject to the workflow described below
• Live documents for which the workflow is not a good fit

Design doc workflow

New proposals follow the design process and are sent for review as a GitHub discussion.

State diagram of the design process

stateDiagram-v2    
    ur: Under review
    
    Draft --> ur
    ur --> Approved
    Approved --> Implemented
    Draft --> Dropped
    ur --> Dropped
    Approved --> Dropped
    
    classDef success fill:#ded
    classDef failure fill:#fcc
    
    class Implemented success
    class Dropped failure

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Live documents

Last updated	Title	Author(s) alias
2023-10-09	Starlark Rules Roadmap	@comius
2023-09-26	Bazelbuild Repositories Maintenance Guide	@comius and @meteorcloudy
2023-08-30	Bazel Proto Rules	@comius
2023-08-01	Problems with Bazel's code coverage collection	@c-mita
2023-07-27	A Guide to Skyframe StateMachines	@aoeui
2022-02-17	The Bazel codebase	@lberki

Design docs

Under review

Last updated	Title	Author(s) alias	Category
2025-03-12	Executing WebAssembly in repository rules	@jmillikin	External Repositories
2024-12-07	Starlark API for Baseline Coverage	@fmeum	Code Coverage, BES
2024-07-31	SEP-001 Bootstraping Starlark Types	@comius	Starlark
2023-12-12	--remote_local_fallback Respects Strategy Declarations	@Silic0nS0ldier	Configurability, Execution Strategy
2023-10-25	C++20 Modules Support	@PikachuHyA	C++
2023-09-12	Proto toolchainization	@comius	Protos
2023-08-08	Inheritance of Target Incompatibility	@fmeum	Platforms, Configurability
2023-06-30	Fingerprinting Starlark Functions	@brandjon	Starlark and actions
2023-06-15	Integrated bzl_library	@brandjon	Starlark
2023-03-17	C/C++ standard resolution for Bazel modules	@fmeum	C++, External Repositories
2023-03-17	More accurate cquery	@gregestren	Configurability

Draft

Last updated	Title	Author(s) alias	Category
2025-04-24	Linking on multiple platforms	@comius	C++ linking
2024-08-29	A New Code Coverage API	@c-mita	Code Coverage
2022-04-29	@since(version) annotations in documentation.	@aiuto	Documentation

Approved

Last updated	Title	Author(s) alias	Category
2025-04-24	Incremental builds with small memory footprint	@lberki	Core
2025-04-24	Execution platform selection for test actions in multi-platform builds	@fmeum	Configurability, Execution
2025-04-24	Bazel Remote Output Service	@coeuvre	Remote Execution
2025-04-24	A true repository cache	@Wyverald	External Repositories
2024-07-28	Execution Platform Scoped Spawn Strategies	@Silic0nS0ldier	Configurability, Execution Strategy
2024-05-08	Selectively Enabling Execution Platforms	@katre	Configuration
2024-04-29	Starlark Transition Composition	@katre	Configuration
2023-08-14	Platform-based flags	@katre	Platforms
2023-08-08	Standard platform transitions	@katre	Platforms
2023-06-12	Remote Output Service: place bazel-out/ on a FUSE file system	@EdSchouten	Remote Execution
2023-03-07	Build Stamping API for Starlark rules	@buildbreaker2021	Starlark Rules
2023-01-23	Remote Cache Eviction for Build without the Bytes	@coeuvre	Remote Execution
2022-10-11	Renaming applicable_licenses	@aiuto	Configuration
2021-02-15	External directory reshuffling	@lberki	External Repositories
2021-02-15	C++ rules skylark migration plan	@mhlopko	C++
2019-05-08	Android Native to Starlark Migration	@timpeut	Android
2018-08-14	Decoupling android_ndk_repository from Bazel	@jin	Android

Implemented

Last updated	Title	Author(s) alias	Category
2025-04-24	Optional and nodep external dependencies	@Wyverald	External Repositories
2025-04-24	Per-target execution platform constraints for exec groups	@fmeum	Configurability, Execution
2025-04-24	Generic Flag Propagation Model	@aranguyen	Configurability
2025-04-24	Garbage collection for the disk cache	@tjgq	Performance
2025-04-24	Standard exec configurations	@gregestren	Configurability
2025-04-24	Extending Bazel rules	@comius	Starlark Rules
2025-04-23	Extend expand_template() API to reduce retained memory	@hvadehra	Starlark
2025-04-17	Aspect Propagation Controller	@mai93	Rules API
2025-04-17	Dormant Dependencies II	@lberki	Build Language
2025-04-17	subrule: Decomposing Starlark rules	@comius	Starlark Rules
2025-04-17	Deprecating managed_directories	@lberki	External Repositories
2024-06-06	Simplifying lockfile maintenance	@fmeum	External Repositories
2024-03-18	A new home for the host platform	@Wyverald	Configurability, External Repositories
2023-12-06	bazel mod tidy	@fmeum	External dependencies
2023-12-5	Offline & Vendor Modes	@salmasamy	Bazel, External Repositories
2023-05-04	Directory watching API for repo rules	@Wyverald	External Repositories
2023-03-21	Bazel feature detection in Starlark	@Wyverald	General, Starlark Rules
2023-03-20	Automatic use_repo fixups for module extensions	@fmeum	External Repositories
2023-03-14	REPO.bazel	@Wyverald	External Repositories
2023-01-30	Transitive static libraries	@fmeum	C++
2022-12-15	Bzlmod lockfile	@salmasamy	Bazel, External Repositories
2022-09-05	Automatic exec groups for toolchains	@comius @kotlaja	Configurability
2022-08-17	Locating runfiles with Bzlmod	@fmeum	External Repositories, Bazel
2022-06-13	Credential Helpers for Bazel	@Yannic	External Repositories
2022-05-12	Bzlmod External Dependencies Inspection Tool	@andyrinne12	External Repositories
2022-03-18	proto_common module	@comius	Proto Rules
2021-06-23	Improving native.existing_rules	@tetromino, @brandjon	Build Language
2021-06-09	Aspects Propagating other Aspects	@messa	Starlark
2021-04-22	Custom constructors for providers	@brandjon	Build Language
2021-03-24	Java common refactoring	@comius	Java rules
2020-12-22	Injecting Starlark Values Into Builtins	@brandjon	Starlark
2021-03-06	OSS License Declarations	@aiuto	Product
2021-02-15	Rules for software license compliance	@aiuto	License Rules, Bazel
2023-03-31	Optional Toolchains	@katre	Configurability
2022-05-25	Canonical label literals	@Wyverald	External Repositories
2022-03-07	Representing repeatable Starlark flags as config.string_list	@fmeum	Configurability, Build Language
2022-01-14	Proposal for subpackages built-in helper function	@kkress	Bazel
2021-08-02	Bazel Central Registry Policies and Procedures	@meteorcloudy	External Repositories
2021-03-06	Remote Persistent Workers	[@ulfjack]
2021-03-06	Rules authors SIG	@alexeagle	Community
2021-02-18	Require ProtoInfo for proto_lang_toolchain#blacklisted_protos	@Yannic	Protobuf
2021-02-16	Selecting Between Python 2 and 3	@brandjon	Python
2021-02-16	Remote Downloads	@EricBurnett, @jmillikin, @sstriker	External Repositories
2021-02-16	Starlark Directory Expansion in Args MapEach	@haileiyu	Starlark
2021-02-16	Test execution on Windows without Bash	@laszlocsomor	Windows
2021-02-15	Toolchain resolution using configuration flags	@comius	Configurability
2021-02-15	Configured Query Starlark Output	@c-parsons	Configurability, Starlark
2021-02-15	Proposal: new format ‘flag_per_line’ for Args	@vmaverick	Starlark
2021-02-15	cquery somepath: easy mode	@gregestren	Configurability
2021-02-15	Automatically migrating maven_jar to rules_jvm_external	@jin	External Repositories
2021-02-15	Target-level execution properties	@agoulti	Configurability
2021-02-15	Bazel Starlark API: add ctx.resolve_tools	@laszlocsomor	Starlark
2021-02-15	Auto-configured Host Platform	@katre	Configurability
2021-02-15	Multiplex persistent worker	@borkaehw	Bazel
2021-02-15	Starlark Build Configuration	@juliexxia, @gregestren	Configurability
2021-02-15	Crosstool in Skylark	@scentini, @mhlopko	C++
2021-02-15	Declared Providers	@dslomov, @laurentlb	Starlark
2021-02-15	Java Platformization	@comius	Configurability
2021-02-15	Starlark Shorthand Flag Mapping	@WarkahScott	Configurability
2021-02-15	Measuring Configuration Overhead	@gregestren	Configurability
2021-02-15	Action Groups (Multi-Toolchain Resolution)	@juliexxia	Configurability
2021-02-15	Common Bazel Constraints	@gregestren	Configurability
2021-02-15	Starlark Build Configurations - Parameterized-Transitions API	@juliexxia	Configurability
2021-02-15	Partial C++ Starlark API	@oquenchil	C++
2021-02-15	Crosstool in Skylark	@mhlopko	C++
2021-02-15	Shrinking the Bazel binary	@buchgr, @meistert	Bazel
2021-02-15	External C/C++ libraries rules	@ichern	Bazel
2021-02-15	Bazel Runfiles Libraries	@laszlocsomor	Bazel
2021-02-15	Name resolution	@laurentlb	Starlark
2020-10-28	Keepalived remote execution	@coeuvre	Remote Execution
2020-10-19	Bazel External Dependencies Overhaul	@meteorcloudy, @philwo, @Wyverald	External Repositories
2020-09-30	Toolchain Transition Migration	@katre	Configurability
2020-09-30	Toolchain Transitions	@katre	Configurability
2020-09-30	Passing Toolchain Context across Dependencies	@katre	Configurability
2020-05-13	Execution Transitions	@katre	Configurability
2020-05-13	Old Flags to Platform Migration	@aragos	Configurability
2019-12-20	Incompatible Target Skipping	@AustinSchuh, @gregestren	Configurability
2019-12-17	cquery somepath: easy mode	@gregestren	Configurability
2019-12-17	Exposing Target Platform Constraints	@katre	Configurability
2019-10-24	Visibility for source files	@aehlig	Build API
2019-04-22	Move //tools/build_defs/pkg to rules_pkg	@aiuto	Bazel
2019-05-10	Bazel with NPM package manager	@ichern	External Repositories
2019-05-27	Authentication for ctx.download	@aehlig	External Repositories
2019-04-29	Forcing non-cache-hits in the repository cache	@aehlig	External Repositories
2019-04-05	Handling download failures	@aehlig	External Repositories
2018-12-14	Versioned Documentation	@jin	Documentation
2018-11-26	Update Download Functions in repository_ctx	@dkelmer	External Repositories
2018-11-14	Platform Inheritance	@katre	Configurability
2018-11-09	Config Setting Chaining	@gregestren	Configurability
2018-10-29	Progress reporting for external repositories	@aehlig	External Repositories
2018-11-10	Symlinks in Remote Execution	@buchgr	Remote Execution
2018-08-27	Args Directory Support	@tomlu	Starlark
2018-08-20	Skylark API to the C++ toolchain	@mhlopko	C++
2018-08-03	Skyframe threading model	@tomlu	Skyframe
2018-07-13	Bazel hashing of external directory output	@aehlig	External Repositories
2018-05-24	Unified Configuration Transitions	@gregestren	Configurability
2018-04-26	Per-Rule Execution Platform Constraints	@katre	Configurability
2017-10-06	Dynamic Bazel Configurations	@gregestren	Configurability
2017-03-03	Label-keyed String Dictionary Type for Build Attributes	@serynth	Configurability
2017-01-20	Aspect required providers	@tomlu, @dslomov	Starlark
2017-01-20	Aspects-on-aspects	@dslomov	Starlark
2016-10-18	Invalidation of remote repositories	@damienmg	External Repositories
2016-10-11	Distribution Artifact for Bazel	@aehlig	Release
2016-09-30	Central cache for external repositories	@jin	External Repositories
2016-09-05	Building Python on Windows	@meteorcloudy	Python, Windows
2016-06-21	Specifying environment variables	@aehlig	Bazel
2016-06-02	Sandboxing	@philwo	Bazel
2016-05-26	Implementing Beautiful Error Messages (Loading Phase)	@laurentlb	Bazel
2016-05-23	Beautiful error messages	@laurentlb	Bazel
2016-04-18	Parameterized Skylark Aspects	@dslomov, lindleyf	Starlark
2016-02-16	Generating C++ crosstool with a Skylark Remote Repository	@damienmg	Toolchains
2015-07-02	Skylark Remote Repositories	@damienmg	External repositories

Dropped

Last updated	Title	Author(s) alias	Category
2025-04-24	Regular rules in module extensions	@matts1	External Repositories
2025-04-24	Better SBOMS: annotated rule attributes	@aiuto
2025-04-24	Modular cc toolchains	@silvergasp	CC toolchain rules
2025-04-24	Adding http mirror to accelerate repos downloading	@yancl	External Repositories
2025-04-24	Better Starlark analysis unit tests	@hvadehra	Starlark
2025-04-24	Introspecting selects	@comius	Configurability
2025-04-24	Bazel Ruleset GOVERNANCE | MECHANICS	@radvani13	Rules
2025-04-17	Extend expand_template() API to reduce retained memory	@hvadehra	Starlark
2025-04-17	Faster aspects: pruning on the way down	@aiuto
2025-04-17	Avoiding accidental secret leaks in the BEP	@jmmv	Core
2025-04-17	Splitting large BEP events	@buchgr	Build Event Protocol
2025-04-17	Dependency adapters for virtual targets	@vdye	Bazel
2024-07-17	Dormant Dependencies	@lberki	Build Language
2023-06-21	Integrated bzl_library	@brandjon	Starlark
2022-02-18	Coding guidelines for Starlark rules	@comius	Starlark Rules
2019-07-11	Load Bazel Protobuf rules from @rules_proto	@Yannic	Protobuf
2022-07-07	Enabling Global exec_groups	@susinmotion	Configurability
2021-06-17	Starlark fail(errorcode="")	@aiuto	Documentation / Event Stream
2023-03-31	Execution Platforms vs. Strategies	@katre and @aragos	Configurability
2021-02-18	Toolchainifying proto rules	@Yannic	Protobuf
2023-03-30	Guidance for Rules Authors how to deal with Bazel versions / upgrades	@philwo	Bazel
2022-11-16	Platforms on Targets	@katre	Configuration
2021-07-21	Monorepo Toolchain Registration	@katre	Toolchains
2021-02-16	Semantics of the expansion of Labels	@aehlig	External Repositories
2021-02-16	Propagate tags from the targets to actions	@ishikhman	Bazel, Starlark
2021-02-16	Remote Repository Cache	jmillikin	External Repositories
2021-02-16	Moving Skylark out of Bazel	@brandjon	Starlark
2021-02-16	Dependency Discovery Proposal	@stevebillings	External Repositories
2021-02-16	s/skydoc/stardoc/g: a plan	@jin	Documentation
2021-02-16	Experimental Content-Based Output Paths	@gregestren	Configurability
2021-02-15	Managing Breaking Changes in Bazel	@dslomov	Community
2021-02-15	Separating Build API from Bazel	@c-parsons	Starlark
2021-02-15	Improved Command Line Reporting	@cvcal	Bazel
2021-02-15	Bazel External Dependencies Roadmap	@dslomov	External Repositories
2021-02-15	Aspects Propagating Other Aspects	@lberki	Build API
2021-02-15	Mandatory load() statements in BUILD files	@lberki	Starlark
2021-02-15	Visibility for implicit attributes	@aehlig	Build API
2021-02-15	Structured Compiler Diagnostics	@illicitonion	Build Event Protocol, Build API
2021-02-15	Replacing native <lang>_proto_library rules with Starlark	@Yannic	Protobuf
2021-02-15	Always dirty repository rules	@ichern	External Repositories
2021-02-15	Design for a Python Toolchain	@brandjon	Python
2021-02-15	Bazel Federation	@dslomov, @laurentlb	Community
2021-02-15	On custom shell toolchain for Bazel Starlark rules	@ichern	Toolchains, Starlark
2021-02-15	Recursive Workspaces	@aehlig	External Repositoires
2021-02-15	Resource auto-tuning via flags	@jmmv	Performance
2021-02-15	Repository Remapping Revisited	@dkelmer	External Repositories
2021-02-15	Bazel Rules Curation	@laurentlb	Community
2021-02-15	Extending the design of WORKSPACE files	@aehlig, @dslomov	External Repositories
2021-02-15	Namespaces when using multiple bazel repositories	@aehlig, @dslomov	External Repositories
2021-02-15	Delaying of load statements	@aehlig	External Repositories
2021-02-15	Repository rules with multiple return values	@aehlig	External Repositories
2021-02-15	Diamond Splitting for External Repositories	@dslomov	External Repositories
2021-02-15	Output Map Madness	@brandjon	Starlark
2021-02-15	External Repositories: The Future	@aehlig, @dslomov	External Repositories
2021-02-15	A Brave New World for the Bazel WORKSPACE File	@mattmoor, @dslomov, @davidstanke, @damienmg	External Repositories
2021-02-15	Garbage Collection for the Repository Cache	@aehlig	External Repositories
2021-02-15	Saner Skylark Sets	@dslomov	Starlark
2021-02-15	Customizing the Python Stub Template	@brandjon	Python
2021-02-15	HTTP downloads with Authorization using .netrc	@genrym	External Repositories
2021-02-15	Package Validation Proposal	@kkress	Bazel, Starlark
2020-10-19	Adding a constraint to default target platform	@comius	Configurability
2020-09-30	Bazel Constraint Equality	@aragos	Configurability
2020-09-30	Versioned Runtime APIs under Platforms & Toolchains	@aragos	Configurability
2020-01-16	Starlark project files	@robbertvanginkel	Bazel, Starlark
2019-08-22	Non-Hermetic Tool Paths in Platforms	@aragos	Configurability
2019-08-01	Platforms and Strategies	@katre	Configurability, Execution Strategy
2018-06-14	Platforms and Configurations	@katre	C++, Starlark
2016-09-19	Recursive WORKSPACE file parsing	@kchodorow	External Repositories
2015-03-06	bazel init a.k.a ./configure for Bazel	@damienmg	Bazel