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A tool to audit pip freeze outputs and test version requirements

Project description


NOTE: this package was originally called pipfreeze but was renamed to avoid confusion with the command pip freeze.

Defrost is a command line tool to check if the output of the pip freeze command complies with a set of package requirements defined in a YAML file.


defrost --help

First define a set of package requirements in a YAML file, requirements.yml.

- requirement: foobar>=1.0
  reason: foobar pre-1.0 is no longer supported, please upgrade to 1.x

- requirement: ordereddict<0.0
  reason: OrderedDict is part of Python 2.7 and above. If you are still running Python 2.6, please upgrade!

Then you can pipe the output of pip freeze to defrost while providing the YAML file.

$ pip freeze > freeze.out
$ defrost requirements.yml freeze.out
Package(foobar==1.2) does not satisfy Requirement(foobar>=2.0): foobar pre-1.0 is no longer supported, please upgrade to 1.x

Defrost can also take the pip freeze output as stdin by passing a dash sign - as argument in place of the pip freeze output file.

$ pip freeze | defrost requirements.yml -
Package(foobar==1.2) does not satisfy Requirement(foobar>=2.0): foobar pre-1.0 is no longer supported, please upgrade to 1.x

You can also check whether the YAML file provided is valid with defrost-lint.

$ defrost-lint requirements.yml


pip install defrost


There are 3 fundamental objects available:

  • PipFreeze: a pythonic container of packages that takes a pip freeze output as input.

  • Package: represents a package instance at an exact version (pinned) held by a PipFreeze container (e.g. foo==1.2)

  • Requirement: a requirement for a package represents one version or a range of versions for a given package, e.g. foo>=2.0 is a requirement for all versions of foo greater or equal to 2.0. foo without a version specifier would mean all versions of foo.


PipFreeze takes a pip freeze output as input and builds packages internally.

>>> from defrost import PipFreeze

>>> pip_freeze_output = """\

>>> pip_freeze = PipFreeze(pip_freeze_output)
>>> len(pip_freeze)

>>> list(pip_freeze)
[Package(foo==1.2.3), Package(bar==2.0)]

# test presence of package foo that is less or equal to v2.0
>>> 'foo<=2.0' in pip_freeze

# test presence of any version of package zoo
>>> 'zoo' in pip_freeze

# test can also be done with a Package instance
>>> Package('foo==0.1') in pip_freeze

# ... or with a Requirement
>>> Requirement('bar>=2.0') in pip_freeze

Package deprecation

You can mark packages as deprecated by loading the YAML requirements file and passing the result of it to PipFreeze.load_requirements(). Packages present in PipFreeze will be marked as deprecated if they don’t satisfy the loaded requirements. You can also provide an optional reason to why a package is deprecated.

>>> pip_freeze = PipFreeze("""\

>>> import yaml
>>> reqs = yaml.load(open('my-reqs.yaml'))
>>> pip_freeze.load_requirements(reqs)
>>> pip_freeze.deprecated
[Package(foobar==0.8), Package(ordereddict==1.1)]
>>> for package in pip_freeze.deprecated:
...     print("%s: deprecated=%s, deprecated_by=%s, reason=%s" % (
            package, package.deprecated, package.deprecated_by, package.deprecation_reason
Package(foobar==0.8): deprecated=True, deprecated_by=Requirement(foobar>=1.0), reason=foobar pre-1.0 is no longer supported, please upgrade to 1.x
Package(ordereddict==1.1): deprecated=True, deprecated_by=Requirement(ordereddict<0.0), reason=ordereddict is part of Python 2.7 and above. If you are still running Python 2.6, please upgrade!


Packages take an exact package version as input.

>>> from defrost import Package

>>> package = Package('foo==1.2')
>>> package.version

If you don’t pass an exact version in your requirement it will raise a ValueError.

>>> package = Package('foo')
>>> Package('foo')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: foo does not represent an exact package version; the format should be foo==1.0

You can also manually deprecate packages:

>>> package = Package('foo==1.2')
>>> package.deprecated
>>> package.deprecate(reason='because')
>>> package.deprecated
>>> package.deprecation_reason


A requirement represents a range of package versions.

>>> from defrost import Requirement

>>> req = Requirement('foo>=1.0,<2.0')
>>> req.specifier
[('>=', '1.0'), ('<', '2.0')]

Requirements play well with packages. Using the Python operator in, you can check if a package satifies a requirement.

>>> req = Requirement('foo>=1.0')
>>> Package('foo==1.0') in req
>>> Package('foo==2.0') in req
>>> Package('foo==0.1') in req


  • implement PipFreeze.__getitem__ and PipFreeze.get().



  • gracefully handle comments that may be present in pip freeze output


  • introduce defrost-lint command to test the validity of requirement files.


  • remove attributes Package.raw and Requirement.raw, instead use Package.__str__() and Requirement.__str__().

  • ignore links found in pip freeze output (-f or -e lines)

  • Introduce the notion of deprecation severity. Package.deprecate() now takes a severity kwarg which defaults to "error" and a requirement entry in the YAML file now accepts an optional severity which can be set to error or warn. This affects the exit status code for the command line interface.

  • PipFreeze.load_requirements() would choke if a reason was not provided


  • add attribute Package.deprecated_by

  • method Package.deprecate() takes an optional deprecated_by argument.

  • add command line utility to list deprecated packages given a requirement file and a pip freeze output file.

  • rename project pipfreeze to defrost to avoid confusion with the command pip freeze.


  • sort packages on name and then version such that foo==2.0 comes before foo-bar==1.0 which is not the case when both are treated as plain strings.


  • implement Requirement

  • implement Package

  • implement PipFreeze.__contains__()

  • implement PipFreeze.__len__()

  • drop py26 support

  • remove PipFreeze.satisfies_requirement()

  • implement PipFreeze.load_requirements()


  • implement PipFreeze.__bool__() (py3) and PipFreeze.__nonzero__() (py2)

  • implement PipFreeze.__iter__()


  • implement pipfreeze.PipFreeze

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