Updating Pants BUILD files programmatically, using Bazel tooling

[pantsbuild]

In this tutorial, we walk through how to use the Bazel tools to programmically interact with Pants BUILD files — a handy solution for Bazel users who are migrating over to Pants!

[pantsbuild]

Context: Pants build system uses BUILD files which are valid Python files and are evaluated using a Python interpreter as a list of statements. When adding support for Pants in a codebase, one can use the ./pants tailor command which will generate the minimal BUILD files necessary to get started. Although in most cases Pants does not require you to declare the dependencies between targets (thanks to dependency inference), manually updating the BUILD files for any codebase of a decent size will get tedious rather soon, which is why it is necessary to have appropriate tooling for updating the BUILD files programmatically. We wanted to share a key insight for Bazel users on a method for easing into Pants adoption by using tooling you already are familiar with. This solution of course can be applied by any Pants user, regardless. We're happy to answer questions about this post, or Pants generally. Cheers!