defrost

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.

Usage

defrost --help

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

---
requirements:
- 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

Install

pip install defrost

Library

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

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

>>> from defrost import PipFreeze

>>> pip_freeze_output = """\
foo==1.2.3
bar==2.0
"""

>>> pip_freeze = PipFreeze(pip_freeze_output)
>>> len(pip_freeze)
2

>>> 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
True

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

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

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

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("""\
foobar==0.8
bar==2.0
ordereddict==1.1
""")

>>> 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!

Package

Packages take an exact package version as input.

>>> from defrost import Package

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

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
False
>>> package.deprecate(reason='because')
>>> package.deprecated
True
>>> package.deprecation_reason
'because'

Requirement

A requirement represents a range of package versions.

>>> from defrost import Requirement

>>> req = Requirement('foo>=1.0,<2.0')
>>> req.name
'foo'
>>> 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
True
>>> Package('foo==2.0') in req
True
>>> Package('foo==0.1') in req
False