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feat: enable the definition of conda pin files in order to freeze an … 
…environment. This can drastically increase the robustness because it allows to freeze an environment at a working state. (#1667)

* feat: enable the definition of conda pin files in order to freeze an environment

* fixes and test case

* skip on win

* docs
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@johanneskoester
johanneskoester committed May 19, 2022
1 parent 26e57d6 commit 53972bf
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85 changes: 59 additions & 26 deletions docs/snakefiles/deployment.rst
View file
Expand Up @@ -287,44 +287,41 @@ Note that you need to clean up environments manually for now. However, in many c

Conda deployment also works well for offline or air-gapped environments. Running ``snakemake --use-conda --conda-create-envs-only`` will only install the required conda environments without running the full workflow. Subsequent runs with ``--use-conda`` will make use of the local environments without requiring internet access.

Freezing environments to exactly pinned packages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. _conda_named_env:
If Snakemake finds a special file ending on ``<platform>.pin.txt`` next to a conda environment file (with ``<platform>`` being the current platform, e.g. ``linux-64``), it will try to use the contents of that file to determine the conda packages to deploy.
The file is expected to contain conda's `explicit specification file format <https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html#building-identical-conda-environments>`_.
Snakemake will first try to deploy the environment using that file, and only if that fails it will use the regular enviroment file.

Using already existing named conda environments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This enables to freeze an environment to a certain state, and will ensure that people using a workflow will get exactly the same environments down to the individual package builds, which is in fact very similar to providing the environment encapsulated in a container image.
Generating such pin files for conda environments can be automatically done using `Snakedeploy <https://snakedeploy.readthedocs.io>`_.
Let ``envs/ggplot.yaml`` be the conda environment file used in the example above.
Then, the pinning can be generated with

Sometimes it can be handy to refer to an already existing named conda environment from a rule, instead of defining a new one from scratch.
Importantly, one should be aware that this can **hamper reproducibility**, because the workflow then relies on this environment to be present
**in exactly the same way** on any new system where the workflow is executed. Essentially, you will have to take care of this manually in such a case.
Therefore, the approach using environment definition files described above is highly recommended and preferred.
.. code-block:: bash
Nevertheless, in case you are still sure that you want to use an existing named environment, it can simply be put into the conda directive, e.g.
snakedeploy pin-conda-envs envs/ggplot.yaml
.. code-block:: python
Multiple paths to environments can be provided at the same time; also see ``snakedeploy pin-conda-envs --help``.

rule NAME:
input:
"table.txt"
output:
"plots/myplot.pdf"
conda:
"some-env-name"
script:
"scripts/plot-stuff.R"
Of course, it is **important to update the pinnings** whenever the original environment is modified, such that they do not diverge.

For such a rule, Snakemake will just activate the given environment, instead of automatically deploying anything.
Instead of using a concrete name, it is also possible to provide a name containing wildcards (which must also occur in the output files of the rule), analogous to the specification of input files.
Updating environments
~~~~~~~~~~~~~~~~~~~~~

Note that Snakemake distinguishes file based environments from named ones as follows:
if the given specification ends on ``.yaml`` or ``.yml``, Snakemake assumes it to be a path to an environment definition file; otherwise, it assumes the given specification
to be the name of an existing environment.
When a workflow contains many conda environments, it can be helpful to automatically update them to the latest versions of all packages.
This can be done automatically via `Snakedeploy <https://snakedeploy.readthedocs.io>`_:

.. _singularity:
.. code-block:: bash
snakedeploy update-conda-envs envs/ggplot.yaml
Multiple paths to environments can be provided at the same time; also see ``snakedeploy update-conda-envs --help``.


-------------------------
Providing post-deployment scripts
-------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

From Snakemake 6.14 onwards post-deployment shell-scripts can be provided to perform additional adjustments of a conda environment.
This might be helpful in case a conda package is missing components or requires further configuration for execution.
Expand All @@ -351,6 +348,42 @@ Post-deployment scripts must be placed next to their corresponding environment-f
The path of the conda environment can be accessed within the script via ``$CONDA_PREFIX``.


.. _conda_named_env:

-----------------------------------------------
Using already existing named conda environments
-----------------------------------------------

Sometimes it can be handy to refer to an already existing named conda environment from a rule, instead of defining a new one from scratch.
Importantly, one should be aware that this can **hamper reproducibility**, because the workflow then relies on this environment to be present
**in exactly the same way** on any new system where the workflow is executed. Essentially, you will have to take care of this manually in such a case.
Therefore, the approach using environment definition files described above is highly recommended and preferred.

Nevertheless, in case you are still sure that you want to use an existing named environment, it can simply be put into the conda directive, e.g.

.. code-block:: python
rule NAME:
input:
"table.txt"
output:
"plots/myplot.pdf"
conda:
"some-env-name"
script:
"scripts/plot-stuff.R"
For such a rule, Snakemake will just activate the given environment, instead of automatically deploying anything.
Instead of using a concrete name, it is also possible to provide a name containing wildcards (which must also occur in the output files of the rule), analogous to the specification of input files.

Note that Snakemake distinguishes file based environments from named ones as follows:
if the given specification ends on ``.yaml`` or ``.yml``, Snakemake assumes it to be a path to an environment definition file; otherwise, it assumes the given specification
to be the name of an existing environment.


.. _singularity:

--------------------------
Running jobs in containers
--------------------------
Expand Down
158 changes: 112 additions & 46 deletions snakemake/deployment/conda.py
View file
Expand Up @@ -65,16 +65,27 @@ def __init__(
container_img=None,
cleanup=None,
):
self._conda = Conda(container_img)

self.file = None
self.name = None
self.post_deploy_file = None
self.pin_file = None
if env_file is not None:
self.file = infer_source_file(env_file)

deploy_file = Path(self.file.get_path_or_uri()).with_suffix(
".post-deploy.sh"
)
if deploy_file.exists():
self.post_deploy_file = infer_source_file(deploy_file)

pin_file = Path(self.file.get_path_or_uri()).with_suffix(
f".{self._conda.platform}.pin.txt"
)

if pin_file.exists():
self.pin_file = infer_source_file(pin_file)
if env_name is not None:
assert env_file is None, "bug: both env_file and env_name specified"
self.name = env_name
Expand All @@ -92,6 +103,7 @@ def __init__(
self._content_hash = None
self._content = None
self._content_deploy = None
self._content_pin = None
self._path = None
self._archive_file = None
self._cleanup = cleanup
Expand All @@ -116,6 +128,12 @@ def _get_content_deploy(self):
return self.workflow.sourcecache.open(self.post_deploy_file, "rb").read()
return None

def _get_content_pin(self):
self.check_is_file_based()
if self.pin_file:
return self.workflow.sourcecache.open(self.pin_file, "rb").read()
return None

@property
def _env_archive_dir(self):
return self.workflow.persistence.conda_env_archive_path
Expand All @@ -136,6 +154,12 @@ def content_deploy(self):
self._content_deploy = self._get_content_deploy()
return self._content_deploy

@property
def content_pin(self):
if self._content_pin is None:
self._content_pin = self._get_content_pin()
return self._content_pin

@property
def hash(self):
if self._hash is None:
Expand Down Expand Up @@ -309,9 +333,8 @@ def execute_deployment_script(self, env_file, deploy_file):
os.path.relpath(path=deploy_file, start=os.getcwd())
)
)
conda = Conda(self._container_img)
shell.check_output(
conda.shellcmd(self.address, "sh {}".format(deploy_file)),
self._conda.shellcmd(self.address, "sh {}".format(deploy_file)),
stderr=subprocess.STDOUT,
)

Expand All @@ -324,8 +347,10 @@ def create(self, dryrun=False):
# Read env file and create hash.
env_file = self.file
deploy_file = None
pin_file = None
tmp_env_file = None
tmp_deploy_file = None
tmp_pin_file = None

if not isinstance(env_file, LocalSourceFile) or isinstance(
env_file, LocalGitFile
Expand All @@ -343,9 +368,15 @@ def create(self, dryrun=False):
tmp.write(self.content_deploy)
deploy_file = tmp.name
tmp_deploy_file = tmp.name
if self.pin_file:
with tempfile.NamedTemporaryFile(delete=False, suffix="pin.txt") as tmp:
tmp.write(self.content_pin)
pin_file = tmp.name
tmp_pin_file = tmp.name
else:
env_file = env_file.get_path_or_uri()
deploy_file = self.post_deploy_file
pin_file = self.pin_file

env_path = self.address

Expand Down Expand Up @@ -402,18 +433,17 @@ def create(self, dryrun=False):
)
)
return env_path
conda = Conda(self._container_img)
logger.info(
"Creating conda environment {}...".format(self.file.simplify_path())
)
# Check if env archive exists. Use that if present.
env_archive = self.archive_file
try:
# Touch "start" flag file
os.makedirs(env_path, exist_ok=True)
with open(os.path.join(env_path, "env_setup_start"), "a") as f:
pass

# Check if env archive exists. Use that if present.
if os.path.exists(env_archive):
logger.info("Installing archived conda packages.")
pkg_list = os.path.join(env_archive, "packages.txt")
Expand Down Expand Up @@ -450,46 +480,78 @@ def create(self, dryrun=False):
out = shell.check_output(
cmd, stderr=subprocess.STDOUT, universal_newlines=True
)

else:
# Copy env file to env_path (because they can be on
# different volumes and singularity should only mount one).
# In addition, this allows to immediately see what an
# environment in .snakemake/conda contains.
target_env_file = env_path + ".yaml"
shutil.copy(env_file, target_env_file)

logger.info("Downloading and installing remote packages.")
cmd = " ".join(
[
self.frontend,
"env",
"create",
"--quiet",
'--file "{}"'.format(target_env_file),
'--prefix "{}"'.format(env_path),
]
)
if self._container_img:
cmd = singularity.shellcmd(
self._container_img.path,
cmd,
args=self._singularity_args,
envvars=self.get_singularity_envvars(),
)
out = shell.check_output(
cmd, stderr=subprocess.STDOUT, universal_newlines=True
)

# cleanup if requested
if self._cleanup is CondaCleanupMode.tarballs:
logger.info("Cleaning up conda package tarballs.")
shell.check_output("conda clean -y --tarballs")
elif self._cleanup is CondaCleanupMode.cache:
logger.info(
"Cleaning up conda package tarballs and package cache."
def create_env(env_file, filetype="yaml"):
# Copy env file to env_path (because they can be on
# different volumes and singularity should only mount one).
# In addition, this allows to immediately see what an
# environment in .snakemake/conda contains.
target_env_file = env_path + f".{filetype}"
shutil.copy(env_file, target_env_file)

logger.info("Downloading and installing remote packages.")

subcommand = [self.frontend]
yes_flag = ["--yes"]
if filetype == "yaml":
subcommand.append("env")
yes_flag = []

cmd = " ".join(
subcommand
+ [
"create",
"--quiet",
'--file "{}"'.format(target_env_file),
'--prefix "{}"'.format(env_path),
]
+ yes_flag
)
if self._container_img:
cmd = singularity.shellcmd(
self._container_img.path,
cmd,
args=self._singularity_args,
envvars=self.get_singularity_envvars(),
)
out = shell.check_output(
cmd, stderr=subprocess.STDOUT, universal_newlines=True
)
shell.check_output("conda clean -y --tarballs --packages")

# cleanup if requested
if self._cleanup is CondaCleanupMode.tarballs:
logger.info("Cleaning up conda package tarballs.")
shell.check_output("conda clean -y --tarballs")
elif self._cleanup is CondaCleanupMode.cache:
logger.info(
"Cleaning up conda package tarballs and package cache."
)
shell.check_output("conda clean -y --tarballs --packages")
return out

if pin_file is not None:
try:
logger.info(
f"Using pinnings from {self.pin_file.get_path_or_uri()}."
)
out = create_env(pin_file, filetype="pin.txt")
except subprocess.CalledProcessError as e:
# remove potential partially installed environment
shutil.rmtree(env_path, ignore_errors=True)
advice = ""
if isinstance(self.file, LocalSourceFile):
advice = (
" If that works, make sure to update the pin file with "
f"'snakedeploy pin-conda-env {self.file.get_path_or_uri()}'."
)
logger.warning(
f"Failed to install conda environment from pin file ({self.pin_file.get_path_or_uri()}). "
f"Trying regular environment definition file.{advice}"
)
out = create_env(env_file, filetype="yaml")
else:
out = create_env(env_file, filetype="yaml")

# Execute post-deplay script if present
if deploy_file:
Expand Down Expand Up @@ -562,15 +624,19 @@ def __init__(self, container_img=None, prefix_path=None):
container_img = container_img.path
self.container_img = container_img

info = json.loads(
shell.check_output(
self._get_cmd("conda info --json"), universal_newlines=True
)
)

if prefix_path is None or container_img is not None:
self.prefix_path = json.loads(
shell.check_output(
self._get_cmd("conda info --json"), universal_newlines=True
)
)["conda_prefix"]
self.prefix_path = info["conda_prefix"]
else:
self.prefix_path = prefix_path

self.platform = info["platform"]

# check conda installation
self._check()

Expand Down
10 changes: 10 additions & 0 deletions tests/test_conda_pin_file/Snakefile
View file
@@ -0,0 +1,10 @@
shell.executable("bash")

rule a:
output:
"test.txt"
conda:
"test-env.yaml"
shell:
"rg --version | head -n1 | cut -f2 -d' ' > {output}"

1 change: 1 addition & 0 deletions tests/test_conda_pin_file/expected-results/test.txt
View file
@@ -0,0 +1 @@
13.0.0
9 changes: 9 additions & 0 deletions tests/test_conda_pin_file/test-env.linux-64.pin.txt
View file
@@ -0,0 +1,9 @@
# This file may be used to create an environment using:
# $ conda create --name <env> --file <this file>
# platform: linux-64
@EXPLICIT
https://conda.anaconda.org/conda-forge/linux-64/_libgcc_mutex-0.1-conda_forge.tar.bz2#d7c89558ba9fa0495403155b64376d81
https://conda.anaconda.org/conda-forge/linux-64/libgomp-12.1.0-h8d9b700_16.tar.bz2#f013cf7749536ce43d82afbffdf499ab
https://conda.anaconda.org/conda-forge/linux-64/_openmp_mutex-4.5-2_gnu.tar.bz2#73aaf86a425cc6e73fcf236a5a46396d
https://conda.anaconda.org/conda-forge/linux-64/libgcc-ng-12.1.0-h8d9b700_16.tar.bz2#4f05bc9844f7c101e6e147dab3c88d5c
https://conda.anaconda.org/conda-forge/linux-64/ripgrep-13.0.0-h2f28480_2.tar.bz2#15a0bf4a1260b0a08198eb683eb272fb
4 changes: 4 additions & 0 deletions tests/test_conda_pin_file/test-env.yaml
View file
@@ -0,0 +1,4 @@
channels:
- conda-forge
dependencies:
- ripgrep =12.0

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