BazelCon 2024

Bazel’s rules_python supports using a hermetic python environment at build and test time. However, maintaining sufficient similarity between the environment that unit tests are running in under bazel test and the production environment can be challenging, particularly once things like extension modules with nontrivial native dependencies get involved. The conda ecosystem is primarily for python packages, but also includes packages for nearly all of the native dependencies of those python packages as well. This talk describes the bazel rule-set we use to fetch conda packages and deploy them for use both during the bazel build and test, and in production. These rules allow us to provide our customers with a deployment package which they can simply untar and run on a wide range of linux environments with very limited prerequisites, producing several distinct (but overlapping) environments for different products within our monorepo, at the same time ensuring that our unit tests are running in a nearly identical environment, all while maintaining acceptable build times.