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Update roadmap for Bazel 8.
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{% include "_buttons.html" %}

## Overview

Happy new year to our Bazel community. With the new year, we plan to bring details of our 2023 roadmap. Last year, we published our 2022 year roadmap with our Bazel 6.0 plans. We hope that the roadmap provided informed your build tooling needs. As the Bazel project continues to evolve in response to your needs, we want to share our 2023 update.

With these changes, we’re looking to keep our open-source community informed and included. This roadmap describes current initiatives and predictions for the future of Bazel development, giving you visibility into current priorities and ongoing projects.

## Bazel 7.0 Release
We plan to bring Bazel 7.0 [long term support (LTS)](https://bazel.build/release/versioning) to you in late 2023. With Bazel 7.0 we aim to deliver many of the in progress items and continue to work through feature improvements that our users have been asking for.

### Better cross-platform cache sharing
Enables [cached artifacts](https://docs.google.com/document/d/1o0mrl2DanfV_6kB_Kf_jUdge13CQ8CvCiqeni2o-rvA/edit#heading=h.mvuo768l4ja2) to be shared across different build local (Mac) and remote (Linux) build platforms primarily for Java/Kotlin and Android development, resulting in better performance and efficient cache usage.

### Android app build with Bazel
Manifest & Resource Merger updates to v30.1.3 so Android app developers can use newer manifest merging features like tools:node="merge".

### Remote execution improvements
Bazel 7.0 provides support for asynchronous execution, speeding up remote execution via increased parallelism with flag --jobs.

### Bzlmod: external dependency management system
[Bzlmod](https://bazel.build/docs/bzlmod) automatically resolves transitive dependencies, allowing projects to scale while staying fast and resource-efficient. Bazel 7.0 contains a number of enhancements to [Bazel's external dependency management](https://docs.google.com/document/d/1moQfNcEIttsk6vYanNKIy3ZuK53hQUFq1b1r0rmsYVg/edit#heading=h.lgyp7ubwxmjc) functionality, including:

- Bzlmod turned on by default for external dependency management in Bazel
- Lock file support — enables hermetic build with Bzlmod
- Vendor/offline mode support — allows users to run builds with pre-downloaded dependencies
- Complete repository cache support (caching not only downloads artifacts, but also the final repository content)
- [Bazel Central Registry](https://registry.bazel.build/) includes regular community contribution and adoption of key Bazel rules & projects

### Build analysis metrics
Bazel 7.0 provides analysis-phase time metrics, letting developers optimize their own build performance.

### Build without the Bytes turned on by default
[Builds without the Bytes](https://github.com/bazelbuild/bazel/issues/6862) optimizes performance by avoiding the download of intermediate artifacts and preventing builds from bottlenecking on network bandwidth. Features added include:

- [Support for remote cache eviction with a lease service](https://docs.google.com/document/d/1wM61xufcMS5W0LQ0ar5JBREiN9zKfgu6AnHVD7BSkR4/edit#heading=h.mflzzzunlhlz), so that users don’t run into errors when artifacts are evicted prematurely

- Address feature gaps in symlink support
- Provide options to retrieve intermediate outputs from remote actions

### Build Productivity with Skymeld
Bazel 7.0 introduces Skymeld — an evaluation mode that reduces the wall time of your multi-target builds. Skymeld eliminates the barrier between analysis and execution phases to improve build speeds, especially for builds with multiple top-level targets. However, for single-target builds, no significant difference is expected.

## Bazel Ecosystem & Tooling

### Android app build with Bazel
- Migrate Android native rules to Starlark: For Bazel 7.0 the Android rules migrate to Starlark to decouple development from Bazel itself and to better enable community contributions. Additionally, we have made these rules independent of the core Bazel binary, allowing us to release more frequently.
- [Migration of Android rules to Starlark](https://bazel.build/reference/be/android)
- R8 support: Allows Android app developers to use R8 updated optimizations.
- Mobile Install: Allows Android app developers to develop, test, deploy any Android app changes quickly through an updated version of [Mobile Install](https://bazel.build/docs/mobile-install).

### Software Bill of Materials data generation (SBOMs) & OSS license compliance tools
With Bazel, developers can generate data to help produce [SBOMs](https://security.googleblog.com/2022/06/sbom-in-action-finding-vulnerabilities.html). This data outputs in text or JSON format, and can be easily formatted to meet [SPDX](https://spdx.dev/specifications/) or [CycloneDX](https://cyclonedx.org/specification/overview/) specifications. Additionally, the process provides rules to declare the licenses Bazel modules are made available under, and tools to build processes around those declarations. See the in-progress [rules_license implementation](https://github.com/bazelbuild/rules_license) on GitHub.

### Signed builds
Bazel provides trusted binaries for Windows and Mac signed with Google keys. This feature enables multi-platform developers/dev-ops to identify the source of Bazel binaries and protect their systems from potentially malicious, unverified binaries.

### Migration of Java, C++, and Python rules to Starlark
Complete migration of Java, C++, and Python rulesets to Starlark. This effort allows Bazel users to fork only rulesets and not Bazel binary codebase, allowing users to

- Update and customize rules as needed
- Update rules independently of Bazel

### Bazel-JetBrains* IntelliJ IDEA support
Incremental IntelliJ plugin updates to support the latest JetBrains plugin release.

*This roadmap snapshots targets, and should not be taken as guarantees. Priorities are subject to change in response to developer and customer feedback, or new market opportunities.*

*To be notified of new features — including updates to this roadmap — join the [Google Group](https://groups.google.com/g/bazel-discuss) community.*

*Copyright © 2022 JetBrains s.r.o. JetBrains and IntelliJ are registered trademarks of JetBrains s.r.o
## Overview {:#overview}

As the Bazel project continues to evolve in response to your needs, we want to
share our 2024 update.

This roadmap describes current initiatives and predictions for the future of
Bazel development, giving you visibility into current priorities and ongoing
projects.

## Bazel 8.0 Release {:#bazel-8.0}

We plan to bring Bazel 8.0 [long term support
(LTS)](https://bazel.build/release/versioning) to you in late 2024.
The following features are planned to be implemented.

### Bzlmod: external dependency management system {:#bzlmod:-external}

[Bzlmod](https://bazel.build/docs/bzlmod) automatically resolves transitive
dependencies, allowing projects to scale while staying fast and
resource-efficient.

With Bazel 8, we will disable WORKSPACE support by default (it will still be
possible to enable it using `--enable_workspace`); with Bazel 9 WORKSPACE
support will be removed. Starting with Bazel 7.1, you can set
`--noenable_workspace` to opt into the new behavior.

Bazel 8.0 will contain a number of enhancements to
[Bazel's external dependency management]
(https://docs.google.com/document/d/1moQfNcEIttsk6vYanNKIy3ZuK53hQUFq1b1r0rmsYVg/edit#heading=h.lgyp7ubwxmjc)
functionality, including:

* The new flag `--enable_workspace` can be set to `false` to completely
disable WORKSPACE functionality.
* New directory watching API (see
[#21435](https://github.com/bazelbuild/bazel/pull/21435), shipped in Bazel
7.1).
* Improved scheme for generating canonical repository names for better
cacheability of actions across dependency version updates.
([#21316](https://github.com/bazelbuild/bazel/pull/21316), shipped in Bazel
7.1)
* An improved shared repository cache (see
[#12227](https://github.com/bazelbuild/bazel/issues/12227)).
* Vendor and offline mode support — allows users to run builds with
pre-downloaded dependencies (see
[#19563](https://github.com/bazelbuild/bazel/issues/19563)).
* Reduced merge conflicts in lock files
([#20396](https://github.com/bazelbuild/bazel/issues/20369)).
* Segmented MODULE.bazel
([#17880](https://github.com/bazelbuild/bazel/issues/17880))
* Allow overriding module extension generated repository
([#19301](https://github.com/bazelbuild/bazel/issues/19301))
* Improved documentation (e.g.
[#18030](https://github.com/bazelbuild/bazel/issues/18030),
[#15821](https://github.com/bazelbuild/bazel/issues/15821)) and migration
guide and migration tooling.

### Remote execution improvements {:#remote-execution}

* Add support for asynchronous execution, speeding up remote execution by
increased parallelism with flag `--jobs`.
* Make it easier to debug cache misses by a new compact execution log,
reducing its size by 100x and its runtime overhead significantly (see
[#18643](https://github.com/bazelbuild/bazel/issues/18643)).
* Implement garbage collection for the disk cache (see
[#5139](https://github.com/bazelbuild/bazel/issues/5139)).
* Implement remote output service to allow lazy downloading of arbitrary build
outputs (see
[#20933](https://github.com/bazelbuild/bazel/discussions/20933)).

### Migration of Android, C++, Java, Python, and Proto rules {:#migration-android,}

Complete migration of Android, C++, Java, and Python rulesets to dedicated
repositories and decoupling them from the Bazel releases. This effort allows
Bazel users and rule authors to

* Update rules independently of Bazel.
* Update and customize rules as needed.

The new location of the rulesets is going to be `bazelbuild/rules_android`,
`rules_cc`, `rules_java`, `rules_python` and `google/protobuf`. `rules_proto` is
going to be deprecated.

Bazel 8 will provide a temporary migration flag that will automatically use the
rulesets that were previously part of the binary from their repositories. All
the users of those rulesets are expected to eventually depend on their
repositories and load them similarly to other rulesets that were never part of
Bazel.

Bazel 8 will also improve on the existing extending rules and subrule APIs and
mark them as non-experimental.

### Starlark improvements {:#starlark-improvements}

* Symbolic Macros are a new way of writing macros that is friendlier to
`BUILD` users, macro authors, and tooling. Compared to legacy macros, which
Bazel has only limited insight into, symbolic macros help users avoid common
pitfalls and enforce best practices.
* Package finalizers are a proposed feature for adding first-class support for
custom package validation logic. They are intended to help us deprecate
`native.existing_rules()`.

### Configurability {:#configurability}

* Output path mapping continues to stabilize: promising better remote cache
performance and build speed for rule designers who use transitions.
* Automatically set build flags suitable for a given `--platforms`.
* Define project-supported flag combinations and automatically build targets
with default flags without having to set bazelrcs.
* Don't redo build analysis every time build flags change.

### Project Skyfocus - minimize retained data structures {:#project-skyfocus}

Bazel holds a lot of state in RAM for fast incremental builds. However,
developers often change a small subset of the source files (e.g. almost never
one of the external dependencies). With Skyfocus, Bazel will provide an
experimental way to drop unnecessary incremental state and reduce Bazel's memory
footprint, while still providing the same fast incremental build experience.

The initial scope aims to improve the retained heap metric only. Peak heap
reduction is a possibility, but not included in the initial scope.

### Misc {:#misc}

* Mobile install v3, a simpler and better maintained approach to incrementally
deploy Android applications.
* Garbage collection for repository caches and Bazel's `install_base`.
* Reduced sandboxing overhead.

### Bazel-JetBrains* IntelliJ IDEA support {:#bazel-jetbrains*-intellij}

Incremental IntelliJ plugin updates to support the latest JetBrains plugin
release.

*This roadmap snapshots targets, and should not be taken as guarantees.
Priorities are subject to change in response to developer and customer
feedback, or new market opportunities.*

*To be notified of new features — including updates to this roadmap — join the
[Google Group](https://groups.google.com/g/bazel-discuss) community.*

*Copyright © 2022 JetBrains s.r.o. JetBrains and IntelliJ are registered trademarks of JetBrains s.r.o

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