README.md

rules_conda

---

Rules for creating conda environments in Bazel 💚

For more info see the docs or the example.

Requirements

rules_conda don't have any strict requirements by themselves.

Just make sure you are able to use conda.

Quickstart

Add this to your WORKSPACE file:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "rules_conda",
    sha256 = "9793f86162ec5cfb32a1f1f13f5bf776e2c06b243c4f1ee314b9ec870144220d",
    url = "https://github.com/spietras/rules_conda/releases/download/0.1.0/rules_conda-0.1.0.zip"
)

load("@rules_conda//:defs.bzl", "conda_create", "load_conda", "register_toolchain")

load_conda(quiet = False)

conda_create(
    name = "py3_env",
    environment = "@//:environment.yml",
    quiet = False,
)

register_toolchain(py3_env = "py3_env")

After that, all Python targets will use the environment specified in register_toolchain.

See below for more advanced example.

Advanced example

This example shows all possibilities of rules_conda:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "rules_conda",
    sha256 = "9793f86162ec5cfb32a1f1f13f5bf776e2c06b243c4f1ee314b9ec870144220d",
    url = "https://github.com/spietras/rules_conda/releases/download/0.1.0/rules_conda-0.1.0.zip",
)

load("@rules_conda//:defs.bzl", "conda_create", "load_conda", "register_toolchain")

load_conda(
    conda_version = "4.10.3",  # version of conda to download, default is 4.10.3
    installer = "miniforge",  # which conda installer to download, either miniconda or miniforge, default is miniconda
    install_mamba = True,  # whether to install mamba, which is a faster drop-in replacement for conda, default is False
    mamba_version = "0.17.0",  # version of mamba to install, default is 0.17.0
    quiet = False,  # True if conda output should be hidden, default is True
    timeout = 600,  # how many seconds each execute action can take, default is 3600
)

conda_create(
    name = "py3_env",  # name of the environment
    environment = "@//:py3_environment.yml",  # label pointing to environment configuration file
    use_mamba = True,  # Whether to use mamba to create the conda environment. If this is True, install_mamba must also be True
    clean = False,  # True if conda cache should be cleaned (less space taken, but slower subsequent builds), default is False
    quiet = False,  # True if conda output should be hidden	True, default is True
    timeout = 600,  # how many seconds each execute action can take, default is 3600
)

conda_create(
    name = "py2_env",  # name of the environment
    environment = "@//:py2_environment.yml",  # label pointing to environment configuration file
)

register_toolchain(
    py2_env = "py2_env",  # python2 is optional
    py3_env = "py3_env",
)

Who should use this?

These rules allow you to download and install conda, create conda environments and register Python toolchain from environments. This means you can achieve truly reproducible and hermetic local Python environments.

Pros:

• easy to use
• no existing conda installation necessary
• no global conda installation, no global PATH modifications
• virtually impossible to corrupt your environment by mistake as it always reflects your environment.yml
• all Python targets will implicitly have access to the whole environment (the one registered in toolchain)

Cons:

• every time you update your environment configuration in environment.yml, the whole environment will be recreated from scratch (but cached package data can be reused)
• on Windows you need to add environment location to PATH or set CONDA_DLL_SEARCH_MODIFICATION_ENABLE=1 during runtime, so DLLs can be loaded properly (more on that here)

So I think these rules suit you if:

• you want to use Bazel (e.g. you fell into Python monorepo trap)
• you want to use conda for Python environment management
• you don't want to set up your Python environment manually or want your Python targets to just work on clean systems
• you are okay with environments being recreated every time something changes