1. Usage: polyvers cmdline-tool

1.1. Tutorial

1.1.1. Install the tool

And you get the polyvers command:

$ pip install polyvers
$ polyvers --version
$ polyvers --help

$ polyvers status
polyvers: Neither `setup.py` nor `.polyvers(.json|.py|.salt)` config-files found!


Actually two projects are installed:

  • polyvers cmd-line tool, for developing python monorepos,
  • polyversion: the base python library used by projects developed with polyvers tool, so that their sources can discover their subproject-version on runtime from Git.

1.1.2. Prepare project

Assuming our monorepo project /monorepo.git/ contains two sub-projects, then you need enter the following configurations into your build files:

    +--setup.py               # see below for contents
    |                         from polyversion import polyversion, polytime
    |                         __version__ = polyversion()
    |                         __updated__ = polytime()
    |                         ...
        +--setup.py:          # like above
        +--core/__init__.py   # like above


You may see different sample approaches for your setup-files by looking into both polyvers & polyversion subprojects of this repo (because they eat their own dog food).

The polyversion library function as a setuptools “plugin”, and adds a new setup() keyword polyversion = (bool | dict) (see polyversion.init_plugin_kw() for its content), which you can use it like this:

from setuptools import setup

    version=''              # omit (or None) to abort if cannot auto-version
    polyversion={           # dict or bool
        'version_scheme: 'mono-project',
        ...  # See `polyversion.init_plugin_kw()` for more keys.
    setup_requires=[..., 'polyversion'],


The setup_requires=['polyvers'] keyword (only available with setuptools, and not distutils), enables the new polyversion= setup-keyword.

Alternatively, a subproject may use PEP 0518 to pre-install polyversion library before pip-installing or launching setup.py script. To do that, add the pyproject.toml file below next to your setup script:

requires = ["setuptools", "wheel", "polyversion"]

and then you can simply import polyversion from your setup.py:

from setuptools import setup
from polyversion import polyversion

    version=polyversion(mono_project=True)  # version implied empty string.


To properly install a PEP 0518 project you need pip-v10+ version.

1.1.3. Initialize polyvers

…we let the tool auto-discover the mapping of project folders ↔ project-names and create a traitlets configuration YAML-file named as /monorepo.git/.polyvers.py:

$ cd monorepo.git

$ polyvers init --monorepo
Created new config-file '.polyvers.yaml'.

$ cat .polyvers.yaml
  - pname: mainprog     # name extracted from `setup.py`.
    basepath: .         # path discovered by the location of `setup.py`
  - pname: core
    basepath: core-lib

$ git add .polyvers.yaml
$ git commit -m 'add polyvers config-gile'

And now we can use the polyvers command to inspect the versions of all sub-projects:

$ polyvers status
- mainprog
- core

Indeed there are no tags in in git-history for the tool to derive and display project-versions, so only project-names are shown. With --all option more gets displayed:

$ polyvers status -a
- pname: mainprog
  basepath: .
  history: []
- pname: core
  basepath: core-lib
  history: []

..where gitver would be the result of git-describe.

1.1.4. Bump versions

We can now use tool to set the same version to all sub-projects:

$ polyvers bump 0.0.0 -f noengraves   # all projects implied, if no project-name given
00:52:06       |WARNI|polyvers.bumpcmd.BumpCmd|Ignored 1 errors while checking if at least one version-engraving happened:
  ignored (--force=noengraves): CmdException: No version-engravings happened, bump aborted.
00:52:07       |NOTIC|polyvers.bumpcmd.BumpCmd|Bumped projects: mainprog-0.0.0 --> 0.0.0, core-0.0.0 --> 0.0.0

The --force=noengraves disables a safety check that requires at least one file modification for engraveing the current version in the leaf “Release” commit (see next step).

 $ polyvers status
 - mainprog-v0.0.0
 - core-v0.0.0

 $ git lg    # Ok, augmented `lg` output a bit here...HEAD --> UPPER branch.
 ======= ====== ==================== ========================================
      O  latest mainprog-r0.0.0      - x2 tags on "Release" leaf-commit
     /          core-r0.0.0            outside-of-trunk (not in HEAD).
    O    MASTER mainprog-v0.0.0      - x2 tags on "Version" commit
    |           core-v0.0.0            for bumping both projects to v0.0.0
    O                                - Previous commit, before version bump.

.. Hint::
   Note the difference between ``ABC-v0.0.0`` vs ``ABC-r0.0.0`` tags.

In the source code, it's only the "release" commit that has :term:`engrave`\d* version-ids:

.. code-block:: console

 $ cat mainprog/mainprog/__init__.py    # Untouched!
 import polyvers

 __title__     = "mainprog"
 __version__ = polyvers.version('mainprog')

 $ git checkout  latest
 $ cat mainprog/mainprog/__init__.py
 import polyvers

 __title__     = "mainprog"
 __version__ = '0.0.0'

 $ git checkout  -  # to return to master.

1.1.5. Engrave version in the sources

Usually programs report their version somehow when run, e.g. with `cmd --version. With polyvers we can derive the latest from the tags created in the previous step, using a code like this, usually in the file /mainprog/mainprog/__init__.py::

import polyvers

__title__ = "mainprog"
__version__ = polyvers.version('mainprog')

…and respectively /core-lib/core/__init__.py::

__version__ = polyvers.version('core')

1.1.6. Bump sub-projects selectively

Now let’s add another dummy commit and then bump ONLY ONE sub-project:

$ git commit  --allow-empty  -m "some head work"
$ polyvers bump ^1 mainprog
00:53:07       |NOTIC|polyvers.bumpcmd.BumpCmd|Bumped projects: mainprog-0.0.0 --> 0.0.1

$ git lg
======= ====== ==================== ========================================
     O  latest mainprog-r0.0.1.dev0 - The latest "Release" leaf-commit.
    /                                 branch `latest` was reset non-ff.
   O    MASTER mainprog-v0.0.1.dev0 - The latest "Version" commit.
   O                                - some head work
   | O         mainprog-r0.0.0      - Now it's obvious why "Release" commits
   |/          core-r0.0.0            are called "leafs".
   O           mainprog-v0.0.0
   |           core-v0.0.0

$ git checkout latest
$ cat mainprog/mainprog/__init__.py
import polyvers

__title__     = "mainprog"
__version__ = '0.0.1.dev0'

$ cat core/core/__init__.py
import polyvers

__title__ = "core"
__version__ = '0.0.0+mainprog.0.0.1.dev0'
$ git checkout -

Notice how the the “local” part of PEP-440 (statring with +...) is used by the engraved version of the un-bumped core project to signify the correlated version of the bumped mainprog. This trick is not necessary for tags because they apply repo-wide, to all sub-projects.

1.2. Features

PEP 440 version ids

While most versioning tools use Semantic versioning, python’s distutils native library supports the quasi-superset, but more versatile, PEP-440 version ids, like that:

  • Pre-releases: when working on new features:

    X.YbN               # Beta release
    X.YrcN  or  X.YcN   # Release Candidate
    X.Y                 # Final release
  • Post-release:

    X.YaN.postM         # Post-release of an alpha release
    X.YrcN.postM        # Post-release of a release candidate
  • Dev-release:

    X.YaN.devM          # Developmental release of an alpha release
    X.Y.postN.devM      # Developmental release of a post-release
version-bump algebra
When bumping, the increment over the base-version can be specified with a “relative version”, which is a combination of PEP 0440 segments and one of these modifiers: +^~= See polyvers.vermath for more.
repo scheme

whether a git repo hosts a single or multiple subprojects


When your single project succeeds, problems like these are known only too well:

Changes in web-server part depend on core features that cannot go public because the “official” wire-protocol is freezed.

While downstream projects using core as a library complain about its bloated transitive dependencies (asking why flask library is needed??).

So the time to “split the project” has come. But from Lerna:

«Splitting up large codebases into separate independently versioned packages is extremely useful for code sharing. However, making changes across many repositories is messy and difficult to track, and testing across repositories gets complicated really fast.»

So a monorepo [1] [2] is the solution. But as Yarn put it:

«OTOH, splitting projects into their own folders is sometimes not enough. Testing, managing dependencies, and publishing multiple packages quickly gets complicated and many such projects adopt tools such as …»

Polyvers is such a tool.

version scheme

the pattern for version-tags. 2x2 versioning schemes are pre-configured, for mono-project and monorepo repositories, respectively:

release scheme
out-of-trunk commit
leaf commit
release tag
version tag

Even in single-project repos, sharing code across branches may cause merge-conflicts due to the version-ids engraved” in the sources. In monorepos, the versions proliferate, and so does the conflicts.

Contrary to Similar Tools, static version-ids are engraved only in out-of-trunk (leaf) commits, and only when the sub-projects are released. In-trunk code is never touched, and version-ids are reported, on runtime, based on Git tags (like git-describe), so they are always up-to-date.

the search-n-replace in files, to substitute the new version. Default grep-like substitutions are included, which can be re-configured in the .polyvers.yaml config file.
setuptools plugin
setuptools integration
The polyversion library function as a setuptools “plugin”, and adds a new setup() keyword polyversion = (bool | dict) (see polyversion.init_plugin_kw() for its content).

When the setuptools:setup() keyword polyversion_check_bdist_enabled = True the setuptools plugin aborts any bdist… commands if they are not run from engraved sources, (ie from an r-tag).

To enable this check without editing the sources, add the following into your $CWD/setup.cfg file:

polyversion_check_bdist_enabled = true
Marking dependent versions across sub-projects
[TODO] When bumping the version of a sub-project the “local” part of PEP-440 on all other the dependent sub-projects in the monorepo signify their relationship at the time of the bump.
Lock release trains as “developmental”
[TODO] Specific branches can be selected always to be published into PyPi only as PEP-440’s “Developmental” releases, meanining that users need pip install --pre to install from such release-trains. This is a safeguard to avoid accidentally landing half-baked code to users.
default version env-var
From which env-var to read a project’s version if git cmd fail. It does not override any value given as default_version keyword for polyversion.polyversion(). Also polyversion.polytime() assumes keyword no_raise=True if such env-var is found. [Default var-name: <pname>_VERSION]
Other Features
  • Highly configurable using traitlets, with sensible defaults; it should be possible to start using the tool without any config file (see init cmd), or by adding one of the flags --monorepo/--mono-project in all commands, in the face of conflicting tags.
  • Always accurate version reported on runtime when run from git repos (never again wonder with which version your experimental-data were produced).

1.2.1. Known Limitations, Drawbacks & Workarounds

  • PEP440 Epoch handling is not yet working.

  • Version-bump’s grammar is not yet as described in “GRAMMAR” section of command’s doc:

    $ polyvers config desc --class BumpCmd
    Increase or set the version of project(s) to the (relative/absolute) version.
        polyvers config desc [OPTIONS] <version> [<project>]...
    - If no project(s) specified, increase the versions on all projects.
    - Denied if version for some projects is backward-in-time (or has jumped parts?);
      use --force if you might.
    VERSION: - A version specifier, either ABSOLUTE, or RELATIVE to the current
    version og each project:
      - *ABSOLUTE* PEP-440 version samples:
        - Pre-releases: when working on new features:
            X.YbN               # Beta release
            X.YrcN  or  X.YcN   # Release Candidate
            X.Y                 # Final release
  • (not related to this tool) In setup.py script, the kw-argument package_dir={'': <sub-dir>} arg is needed for py_modules to work when packaging sub-projects (also useful with find_packages(), check this project’s sources). But <sub-dir> must be relative to launch cwd, or else, pip install -e <subdir> and/or python setup.py develop break.

  • (not related to this tool) When building projects with python setup.py bdist_XXX, you have to clean up your build directory (e.g. python setup.py clean --all) or else, the distribution package will contain the sources from all previous subprojects built. That applies also when rebuilding a project between versions.

  • Installing directly from git-repos needs an engraved branch (e.g. latest):

    pip install git+https://github.com/JRCSTU/polyvers@latest

    If you still want to install non-engraved branhces (e.g. master), set the default version env-var; for example, since polyvers subproject has not customized the name of its env-var, you may install the very latest like this:

    polyvers_VERSION=1.2.3 pip install git+https://github.com/JRCSTU/polyvers


    The version given in the env-var is irrelevant. The installed version will still derive from git tags, and the local-part from the actual git-commit.

  • (not related to this tool) If you don’t place a setup.py file at the root of your git-repo (using package_dir argument to setup() function or in find_packages(), according to setuptools-docs), then in order to pip install git+https://... directly from remote URLs you have to use this official trick. For example, to install polyversion subproject:

    pip install "git+https://github.com/JRCSTU/polyvers@latest#egg=polyversion&subdirectory=pvlib"

    Notice that the quotes are needed to escape the & char from bash. Respectively, use this to install from the very latest:

    polyversion_VERSION=1.2.3 pip install git+https://github.com/JRCSTU/polyvers#egg=polyversion&subdirectory=pvlib"
  • Set branch latest as default in GitHub to show engraved sub-project version-ids.

  • See TODOs.

1.3. Recipes

1.3.1. Automatically sign tags:

Add this to your ~/.polyvers.yaml:

  sign_tags: true
  sign_user: <username-or-keyid>