What's New

Individuals and companies can now sponsor Pants financially.

Pants is an open-source project that is not owned or controlled by any one company or organization, and does incur some expenses. These expenses are managed by Pants Build, a non-profit that was established for this purpose. This non-profit's only source of revenue is sponsorship by individuals and companies that use Pants.

We offer formal sponsorship tiers for companies, as well as individual sponsorships via GitHub.

Overall

The pants launcher binary (aka scie-pants) is now the recommended way to run Pants. Use of a ./pants shell script in a repository is deprecated.

The pants launcher has numerous benefits, such as:

• automatically download and maintain a Python distribution for running Pants
• run pants from any directory within a repository and not just the build root
• far less overhead when starting commands (up to 4-5×)

See the Pants installation instructions for additional information on how to migrate to the pants launcher binary.

Related to this, pants' distribution model is changing, and 2.17 will be the last version where:

• the pantsbuild.pants package is published to PyPI. Use the pants_requirements target for installing the requisite packages for plugins, rather than python_requirement or similar.
• the universal (cross-platform) pants PEX is published to GitHub Releases. For future releases, smaller per-platform PEXes will be attached instead.

Performance

As mentioned above, the new launcher binary reduces start-up overhead.

Large files are now cached as standalone files on disk, rather than stored directly in the internal database pants uses for cache (but still under the ~/.cache/pants/lmdb_store directory). This improves performance for manipulating these files, especially when the cache directory and sandbox temporary directory are on the same file system and thus allow hard-linking.

Backends

Python

Python dependencies are now analyzed via an intrinsic rule implemented in Rust for increased performance over the prior Python implementation of the rule. See #18854 for discusion of the performance improvements.

Exported mutable virtualenvs can now include PEP-660 editable installs of python_distribution targets. To enable this feature for a resolve, add that resolve's name to the [export].py_editables_in_resolves list in pants.toml.
See #18639 for details on Pants' PEP-660 implementation.

The default pip Pants uses under the hood has changed from 20.3.4 to 23.1.2. This newer pip has better dependency resolution performance in many cases, but may give different results than the earlier pip. Of course those results will still be correct in the sense that they will be compatible with your requirements and constraints.

The python_awslambda or python_google_cloud_function targets now support a new 'zip' layout, as recommended by the cloud vendors. This layout gives smaller packages and faster cold starts than the existing Lambdex layout, and will become the default in 2.18. See the docs for python_awslambda and for python_google_cloud_function.

The default value for the [python].interpreter_constraints option was deprecated in 2.16 and is now removed: pants.toml must provide this option. We recommend constraining to a single interpreter minor version if you can, for instance: interpreter_constraints = ['==3.11.*']. See the Interpreter Compatibility docs for more details.

Docker

The Docker backend now supports authenticating with registries via the DOCKER_HOST, DOCKER_CONFIG and DOCKER_CERT_PATH environment variables.

New: Javascript (experimental!)

Pants now has very early experimental support for Javascript thanks to ongoing efforts by Tobias Nilsson and Theo Ribeiro. Please note that the Javascript backend is still incomplete, is being actively developed, and probably has critical bugs. Despite that, the Pants maintainers would appreciate any feedback from the community to help guide our development efforts.

Supported goals are:

• test: Letting you run tests via runners installed with the package manager of your choice.
• package goal, either to run a customized package.json script that produces an artifact via node_build_script, or to pack a tarball for npm-registry publication via the npm_distribution target.
• tailor: Generates build file targets for *.js, *.test.js and package.json files.
• generate-lockfile: Creates the lockfile in the format matching a projects package manager.

The backend supports all package managers provided by corepack. yarn@v2 and PlugNPlay is not supported.

Enable the pants.backend.experimental.javascript backend to try out this support. Please file issues for any issues encountered, and follow along the stabilization ticket on github.

New: Taplo TOML Formatter

Pants now supports the Taplo TOML formatter. Enable the pants.backend.tools.taplo backend to add this support.

Plugin API Changes

Rules should now request output types which do not need an input type via the new one-argument form of Get. For example, rules can now write await Get(ChosenLocalEnvironmentName). Certain request types which exists only to work around the previous lack of such synax are now deprecated in favor of the one argument Get() form.

The PythonBinary type is now deprecated, use PythonBuildStandalone instead.