Package releasing made easy: zest.releaser overview and installation

zest.releaser is collection of command-line programs to help you automate the task of releasing a Python project.

It does away with all the boring bits. This is what zest.releaser automates for you:

  • It updates the version number. The version number can either be in or version.txt or in a __versions__ attribute in a Python file or in setup.cfg. For example, it switches you from 0.3.dev0 (current development version) to 0.3 (release) to 0.4.dev0 (new development version).
  • It updates the history/changes file. It logs the release date on release and adds a new heading for the upcoming changes (new development version).
  • It tags the release. It creates a tag in your version control system named after the released version number.
  • It optionally uploads a source release to PyPI. It will only do this if the package is already registered there (else it will ask, defaulting to ‘no’); zest releaser is careful not to publish your private projects!

Most important URLs

First the three most important links:

And… we’re automatically being tested by Travis and Landscape: Code Health

Compatibility / Dependencies

zest.releaser works on Python 2.7. Python 3.5+ is supported. PyPy2 is supported.

To be sure: the packages that you release with zest.releaser may very well work on other Python versions: that totally depends on your package.

We depend on:

  • setuptools for the entrypoint hooks that we offer.
  • colorama for colorized output (some errors printed in red).
  • six for python2/python3 compatibility.
  • twine for secure uploading via https to pypi. Plain setuptools doesn’t support this.

Since version 4.0 there is a recommended extra that you can get by installing zest.releaser[recommended] instead of zest.releaser. It contains a few trusted add-ons that we feel are useful for the great majority of zest.releaser users:

  • wheel for creating a Python wheel that we upload to PyPI next to the standard source distribution. Wheels are the new Python package format. Create or edit setup.cfg in your project (or globally in your ~/.pypirc) and create a section [zest.releaser] with create-wheel = yes to create a wheel to upload to PyPI. See for deciding whether this is a good idea for your package. Briefly, if it is a pure Python 2 or pure Python 3 package: just do it. If it is a pure Python 2 and a pure Python 3 project, it is known as a “universal” wheel, because one wheel can be installed on all implementations and versions of Python. If you indicate this in setup.cfg with the section [bdist_wheel] having universal = 1, then we will automatically upload a wheel, unless create-wheel is explicitly set to false.
  • check-manifest checks your file for completeness, or tells you that you need such a file. It basically checks if all version controlled files are ending up the the distribution that we will upload. This may avoid ‘brown bag’ releases that are missing files.
  • pyroma checks if the package follows best practices of Python packaging. Mostly it performs checks on the file, like checking for Python version classifiers.
  • chardet, the universal character encoding detector. To do the right thing in case your readme or changelog is in a non-utf-8 character set.
  • readme to check your long description in the same way as pypi does. No more unformatted restructured text on your pypi page just because there was a small error somewhere. Handy.


Just a simple pip install zest.releaser or easy_install zest.releaser is enough. If you want the recommended extra utilities, do a pip install zest.releaser[recommended].

Alternatively, buildout users can install zest.releaser as part of a specific project’s buildout, by having a buildout configuration such as:

parts =

recipe = zc.recipe.egg
eggs = zest.releaser[recommended]

Version control systems: svn, hg, git, bzr

Of course you must have a version control system installed. zest.releaser currently supports:

  • Subversion (svn).
  • Mercurial (hg).
  • Git (git).
  • Git-svn.
  • Bazaar (bzr).

Others could be added if there are volunteers! Git and mercurial support have been contributed years ago when we were working with bzr and subversion, for instance.

Available commands

Zest.releaser gives you four commands to help in releasing python packages. They must be run in a version controlled checkout. The commands are:

  • prerelease: asks you for a version number (defaults to the current version minus a ‘dev’ or so), updates the or version.txt and the CHANGES/HISTORY/CHANGELOG file (with either .rst/.txt/.md/.markdown or no extension) with this new version number and offers to commit those changes to subversion (or bzr or hg or git).
  • release: copies the the trunk or branch of the current checkout and creates a version control tag of it. Makes a checkout of the tag in a temporary directory. Offers to register and upload a source dist of this package to PyPI (Python Package Index). Note: if the package has not been registered yet, it will not do that for you. You must register the package manually (python register) so this remains a conscious decision. The main reason is that you want to avoid having to say: “Oops, I uploaded our client code to the internet; and this is the initial version with the plaintext root passwords.”
  • postrelease: asks you for a version number (gives a sane default), adds a development marker to it, updates the or version.txt and the CHANGES/HISTORY/CHANGELOG file with this and offers to commit those changes to version control. Note that with git and hg, you’d also be asked to push your changes (since 3.27). Otherwise the release and tag only live in your local hg/git repository and not on the server.
  • fullrelease: all of the above in order.

Note: markdown files should use the “underline” style of headings, not the “atx” style where you prefix the headers with # signs.

There are some additional tools:

  • longtest: small tool that renders a’s long description and opens it in a web browser. This assumes an installed docutils (as it needs
  • lasttagdiff: small tool that shows the diff of the current branch with the last released tag. Handy for checking whether all the changes are adequately described in the changes file.
  • lasttaglog: small tool that shows the log of the current branch since the last released tag. Handy for checking whether all the changes are adequately described in the changes file.
  • addchangelogentry: pass this a text on the command line and it will add this as an entry in the changelog. This is probably mostly useful when you are making the same change in a batch of packages. The same text is used as commit message. In the changelog, the text is indented and the first line is started with a dash. The command detects it if you use for example a star as first character of an entry.
  • bumpversion: do not release, only bump the version. A development marker is kept when it is there. With --feature we update the minor version. With option --breaking we update the major version.