# Linting¶

In order to ensure high-quality packages, we now perform routine checks on each recipe (called linting). By default, linting is performed on any recipes that have changed relative to the master branch. The CircleCI build will fail if any of the linting checks fail. Below is a list of the checks performed and how to fix them if they fail.

## Skipping a linting test¶

### Skipping on a per-commit basis¶

While only recommended in special cases, it is possible to skip specific linting tests on a commit by using special text in the commit message, [lint skip $FUNCTION for$RECIPE] where $FUNCTION is the name of the function to skip and $RECIPE is the path to the recipe directory for which this test should be skipped.

For example, if the linter reports a uses_setuptools issue for recipes/mypackage, but you are certain the package really needs setuptools, you can add [lint skip uses_setuptools for recipes/mypackage] to the commit message and this linting test will be skipped on CircleCI. Multiple tests can be skipped by adding additional special text. For example, [lint skip uses_setuptools for recipes/pkg1] [lint skip in_other_channels for recipes/pkg2/0.3.5]. Note in the latter case that the second recipe has a subdirectory for an older version.

Technically we check for the regular expression $\s*lint skip (?P<func>\w+) for (?P<recipe>.*?)\s*$ in the commit message of the HEAD commit. However, often we want to test changes locally without committing. When running locally for testing, you can add the same special text to a temporary environment variable LINT_SKIP. The same example above could be tested locally like this without having to make a commit:

LINT_SKIP="[lint skip uses_setuptools for recipes/mypackage]" circleci build


### Skipping persistently on a per-recipe basis¶

Sometimes a recipe will always fail linting. For example, in rare cases the source for a recipe may only be available as a git_url or may require setuptools as a runtime dependency. In these cases, add an extra: skip-lints list to the meta.yaml indicating which lints should be skipped, for example:

extra:
skip-lints:
- uses_git_url
- uses_setuptools


## Linting functions¶

### in_other_channels¶

Reason for failing: The package exists in another dependent channel (currently conda-forge and defaults). This often happens when a general-use package was added to bioconda first but was subsequently added to one of the more general channels. In this case we’d prefer it to be in the general channel.

Rationale: We want to minimize duplicated work. If a package already exists in another dependent channel, it doesn’t need to be maintained in the bioconda channel.

How to resolve: In special cases this can be overridden, for example if a bioconda-specific patch is required. However it is almost always better to fix or update the recipe in the other channel. Note that the package in the bioconda channel will remain in order to maintain reproducibility.

Reason for failing: The current package version, build, and platform (linux/osx) already exists in the bioconda channel.

Rationale: This acts as an early warning to bump version or build numbers.

How to resolve: Increase the version number or build number as appropriate.

### missing_home¶

Reason for failing: No homepage URL.

Rationale: We want to make sure users can get additional information about a package, and it saves a separate search for the tool. Furthermore some tools with name collisions have to be renamed to fit into the conda channel and the homepage is an unambiguous original source.

### missing_summary¶

Reason for failing: Missing a summary.

Rationale: We want to provide a minimal amount of information about the package.

How to resolve: add a short descriptive summary in the about section.

Reason for failing: No license provided.

Rationale: We need to ensure that adding the package to bioconda does not violate the license

How to resolve: Add the license in the about section. There are some ways of accommodating some licenses; see the GATK package for one method.

### missing_tests¶

Reason for failing: No tests provided.

Rationale: We need at least minimal tests to ensure the programs can be found on the path to catch basic installation errors.

How to resolve: Add basic tests to ensure the software gets installed; see Tests for more info.

### missing_hash¶

Reason for failing: Missing a hash in the source section.

Rationale: Hashes ensure that the source is downloaded correctly without being corrupted.

### should_be_noarch (currently disabled)¶

Reason for failing: The package should be labelled as noarch.

Rationale: A noarch package should be created for pure Python packages, data packages, or packages that do not require compilation. With this a single noarch package can be used across multiple platforms and (in case of Python) Python versions, which saves on build time and saves on storage space on the bioconda channel.

How to resolve: For pure Python packages, add noarch: python to the build section. Don’t do this if your Python package has a command line interface, as these are not independent of the Python version! For other generic packages (like a data package), add noarch: generic to the build section. See here for more details.

### should_not_be_noarch¶

Reason for failing: The package should not be labelled as noarch.

Rationale: The package defines gcc as a dependency, or it contains a build/skip section. In both cases, this means that there should be platform specific versions of this package. This also holds for skipping Python versions, because noarch: python also implies that the resulting package will work with all Python versions. This is typically not the case if you skip a Python version.

How to resolve: Remove the noarch statement.

### uses_git_url¶

Reason for failing: The source section uses a git URL.

Rationale: While this is supported by conda, we prefer to not use this method since it is not always reproducible. Furthermore, the Galaxy team mirrors each successfully built bioconda recipe. Mirroring git_urls is problematic.

How to resolve: Use a direct URL. Ideally a github repo should have tagged releases that are accessible as tarballs from the “releases” section of the github repo.

Reason for failing: The recipe has a dependency of perl-threaded.

Rationale: Previously bioconda used perl-threaded as a dependency for Perl packages, but now we are using perl instead. When one of these older recipes is updated, it will fail this check.

How to resolve: Change perl-threaded to perl.

### uses_javajdk¶

Reason for failing: The recipe has a dependency of java-jdk.

Rationale: Previously bioconda used java-jdk as a dependency for Java packages, but now we are using openjdk instead. When one of those older recipes is updated, it will fail this check.

How to resolve: Change java-jdk to openjdk.

### uses_setuptools (currently disabled)¶

Reason for failing: The recipe has setuptools as a run dependency.

Rationale: setuptools is typically used to install dependencies for Python packages but most of the time this is not needed within a conda package as a run dependency.

How to resolve: Ensure that all dependencies are explicitly defined. Some packages do need setuptools, in which case this can be overridden. setuptools may be required, e.g., if a package loads resources via pkg_resources which is part of setuptools. That dependency can also be introduced implicitly when setuptools-created console scripts are used. To avoid this, make sure to carry console_scripts entry points from setup.py over to meta.yaml to replace them with scripts created by conda/conda-build which don’t require pkg_resources.

### has_windows_bat_file¶

Reason for failing: The recipe includes a .bat file.

Rationale: Often when using one of the skeleton commands (conda skeleton {cran,pypi,cpan}), the command will include a Windows .bat file. Since bioconda does not support Windows, any *.bat files are unused and to reduce clutter we try to remove them.

How to resolve: Remove the .bat file from the recipe.

### setup_py_install_args¶

Reason for failing: The recipe has setuptools as a build dependency, but build.sh needs to use certain arguments when running setup.py.

Rationale: When a package depends on setuptools, we have to disable some parts of setuptools during installation to make it work correctly with conda. In particular, it seems that packages depend on other packages that specify entry points (e.g., pyfaidx) will cause errors about how setuptools is not allowed to install certifi in a conda package.

How to resolve: Change the line in either in build.sh or the build:script key in meta.yaml from:

$PYTHON setup.py install  to: $PYTHON setup.py install --single-version-externally-managed --record=record.txt


### *_not_pinned¶

Reason for failing: The recipe has dependencies that need to be pinned to a specific version all across bioconda.

Rationale: Sometimes when a core dependency (like zlib, which is used across many recipes) is updated it breaks backwards compatibility. In order to avoid this, for known-to-be-problematic dependencies we pin to a specific version across all recipes.

How to resolve: Change the dependency line as follows. For each dependency failing the linting, specify a jinja-templated version by converting it to uppercase, prefixing it with CONDA_, adding double braces, and adding a *.

Examples are much easier to understand:

• zlib should become zlib {{ CONDA_ZLIB }}*
• ncurses should become ncurses {{ CONDA_NCURSES }}*
• htslib should become htslib {{ CONDA_HTSLIB }}*
• boost should become boost {{ CONDA_BOOST }}*
• … and so on.

Here is an example in the context of a meta.yaml file where zlib needs to be pinned:

# this will give a linting error because zlib is not pinned
build:
- zlib
run:
- zlib
- bedtools


And here is the fixed version:

# fixed:
build:
- zlib {{ CONDA_ZLIB }}*
run:
- zlib {{ CONDA_ZLIB }}*
- bedtools


## Developer docs¶

For developers adding new linting functions:

Lint functions are defined in bioconda_utils.lint_functions. Each function accepts three arguments:

• recipe, the path to the recipe
• meta, the meta.yaml file parsed into a dictionary
• df, a dataframe channel info, typically as returned from linting.channel_dataframe and is expected to have the following columns: [build, build_number, name, version, license, platform, channel].

We need recipe because some lint functions check files (e.g., has_windows_bat_file). We need meta because even though we can parse it from recipe within each lint function, it’s faster if we parse the meta.yaml once and pass it to many lint functions. We need df because we need channel info to figure out if a version or build number needs to be bumped relative to what’s already in the channel.

If the linting test passes, the function should return None. Otherwise it should return a dictionary. The keys in the dict will be propagated to columns of a pandas DataFrame for downstream processing and so can be somewhat arbitrary.

After adding a new linting function, add it to the bioconda_utils.lint_functions.registry tuple so that it gets used by default.