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Allow passing callable venv_backend for creation of session virtualenv #753

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160 changes: 160 additions & 0 deletions docs/cookbook.rst
Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,166 @@ Enter the ``dev`` nox session:
With this, a user can simply run ``nox -s dev`` and have their entire environment set up automatically!


Instant Dev Environment using callable venv_backend
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

As an alternative to the above, you can instead invoke a custom callable for ``venv_backend`` to create a development nox session.

.. code-block:: python

from nox.sessions import SessionRunner
from nox.virtualenv import VirtualEnv


def create_venv_override_location(
location: str,
interpreter: str | None,
reuse_existing: bool,
venv_params: Any,
runner: SessionRunner,
) -> VirtualEnv:
"""
Override location of virtualenv

To set the location, pass `venv_params = {"location": path/to/.venv, "venv_params": ...}`
where `venv_params[venv_params]` will be passed to `VirtualEnv` creation.
"""

if not isinstance(venv_params, dict) or "location" not in venv_params:
raise ValueError("must supply `venv_backend = {'location': path, ...}")

# Override the virtual environment location
location = venv_params["location"]
assert isinstance(location, str)

venv = VirtualEnv(
location=location,
interpreter=interpreter,
reuse_existing=reuse_existing,
venv_params=venv_params.get("venv_params"),
)

venv.create()
return venv


@nox.session(
python="3.11",
venv_backend=create_venv_override_location,
venv_params={"location": ".venv"},
)
def dev(session: nox.Session) -> None:
"""Easy way to create a development environment

This will place the development environment in the `.venv` directory
"""
session.install("-e", ".[dev]")




Create environment with ``conda env create``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

It's common to create conda environments directly from an ``environment.yaml``
file with ``conda env create``. There are also cases where using ``micromamba`` is advantageous.
To do this with nox, you can use a callable ``venv_backend``. For example:

.. code-block:: python

import os
from nox.sessions import SessionRunner
from nox.virtualenv import CondaEnv
from nox.logger import logger


def factory_conda_env(backend: str):
"""Create a callable backend with specified conda backend."""
# Override CondaEnv backend
CondaEnv.allowed_globals = ("conda", "mamba", "micromamba") # type: ignore[assignment]

if backend not in CondaEnv.allowed_globals:
msg = f"{backend=} must be in {CondaEnv.allowed_globals}"
raise ValueError(msg)


def create_conda_env(
location: str,
interpreter: str | None,
reuse_existing: bool,
venv_params: Any,
runner: SessionRunner,
) -> CondaEnv:
"""
Custom venv_backend to create conda environment from `environment.yaml` file

This particular callable infers the file from the interpreter. For example,
if `interpreter = "3.8"`, then the environment file will be `environment/py3.8-conda-test.yaml`
"""
if not interpreter:
raise ValueError("must supply interpreter for this backend")

venv = CondaEnv(
location=location,
interpreter=interpreter,
reuse_existing=reuse_existing,
venv_params=venv_params,
conda_cmd=backend,
)

env_file = f"environment/py{interpreter}-conda-test.yaml"

assert os.path.exists(env_file)
# Custom creating (based on CondaEnv.create)
if not venv._clean_location():
logger.debug(f"Re-using existing conda env at {venv.location_name}.")
venv._reused = True

else:
cmd = (
[venv.conda_cmd]
+ (["--yes"] if venv.conda_cmd == "micromamba" else ["env"])
+ ["create", "--prefix", venv.location, "-f", env_file]
)
# cmd = ["conda", "env", "create", "--prefix", venv.location, "-f", env_file]

logger.info(
f"Creating conda env in {venv.location_name} with env file {env_file}"
)
logger.info(f"{cmd}")
nox.command.run(cmd, silent=False, log=nox.options.verbose or False)

return venv

return create_conda_env



@nox.session(python=["3.8"], venv_backend=factory_conda_env("conda"))
def conda_tests(session: nox.Session) -> None:
"""Run test suite in conda environment."""
# Note that all extra dependencies are assumed to
# be installed during environment creation
session.install("-e", ".", "--no-deps")
session.run("pytest", *session.posargs)


@nox.session(python=["3.8"], venv_backend=factory_conda_env("micromamba"))
def micromamba_tests(session: nox.Session) -> None:
"""Run test suite in micromamba environment."""
# Note that all extra dependencies are assumed to
# be installed during environment creation
session.install("-e", ".", "--no-deps")
session.run("pytest", *session.posargs)

Note that this scheme can be extended to use, for example, `conda-lock
<https://github.com/conda/conda-lock>`_ to install locked environments.






The Auto-Release
^^^^^^^^^^^^^^^^

Expand Down
7 changes: 7 additions & 0 deletions docs/tutorial.rst
Original file line number Diff line number Diff line change
Expand Up @@ -410,6 +410,13 @@ incompatible versions of packages already installed with conda.
use/require `mamba <https://github.com/mamba-org/mamba>`_ instead of conda.


Customized virtual environment creation
---------------------------------------

If the builtin methods for creating virtual environments don't fit you exact
needs, you can instead pass a callable for ``venv_backend``. See :doc:`cookbook` for examples.


Parametrization
---------------

Expand Down
72 changes: 72 additions & 0 deletions environment/create_env_files.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,72 @@
import logging
import os
import sys
from pathlib import Path

PYTHON_VERSIONS = ["3.7", "3.8", "3.9", "3.10", "3.11"]
LOCK_VERSIONS = ["3.11"]


logger = logging.getLogger(__name__)


HERE = Path(__file__).resolve().parent


def create_yaml(*deps: str) -> str:
x = ["dependencies:"]
x.extend([f" - {dep}" for dep in deps])
return "\n".join(x) + "\n"


def create_yaml_files():
os.chdir(HERE)
logging.info(f"cwd: {Path.cwd()}")

# load requirements:
requirements = [
x.replace(" ", "")
for x in Path("../requirements-conda-test.txt").read_text().strip().split("\n")
]

# create environment files
for py in PYTHON_VERSIONS:
yaml = Path(f"py{py}-conda-test.yaml")

# make sure these have python and pip
s = create_yaml(f"python={py}", *requirements, "pip")
with yaml.open("w") as f:
f.write(s)


def create_lock_files():
import subprocess

os.chdir(HERE)
for py in LOCK_VERSIONS:
subprocess.run(
[
"conda-lock",
"lock",
"-c",
"conda-forge",
f"--file=py{py}-conda-test.yaml",
f"--lockfile=py{py}-conda-test-conda-lock.yml",
],
stdout=sys.stdout,
stderr=sys.stderr,
)


if __name__ == "__main__":
args = sys.argv[1:]

if not args:
print("pass yaml (to create yaml files) or lock (to create lock files)")

else:
for arg in args:
if arg == "yaml":
create_yaml_files()
elif arg == "lock":
create_lock_files()
9 changes: 9 additions & 0 deletions environment/py3.10-conda-test.yaml
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
dependencies:
- python=3.10
- argcomplete>=1.9.4,<3.0
- colorlog>=2.6.1,<7.0.0
- jinja2
- pytest
- tox<4.0.0
- virtualenv>=14.0.0
- pip
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