Version control repository manager
The Python package vcs-repo-mgr provides a command line program and Python API to perform common operations (in the context of packaging/deployment) on version control repositories. It’s currently tested on Python 2.6, 2.7, 3.4, 3.5 and 3.6 on Linux and Mac OS X. Bazaar, Mercurial and Git repositories are supported.
The vcs-repo-mgr package is available on PyPI which means installation should be as simple as:
$ pip install vcs-repo-mgr
There’s actually a multitude of ways to install Python packages (e.g. the per user site-packages directory, virtual environments or just installing system wide) and I have no intention of getting into that discussion here, so if this intimidates you then read up on your options before returning to these instructions ;-).
$ sudo apt-get install bzr mercurial git-core
There are two ways to use the vcs-repo-mgr package: As the command line program vcs-tool and as a Python API. For details about the Python API please refer to the API documentation available on Read the Docs. The command line interface is described below.
Usage: vcs-tool [OPTIONS] [ARGS]
Command line program to perform common operations (in the context of packaging/deployment) on version control repositories. Supports Bazaar, Mercurial and Git repositories.
Select a repository to operate on by providing the name of a repository defined in one of the configuration files ~/.vcs-repo-mgr.ini and /etc/vcs-repo-mgr.ini.
Alternatively the location of a remote repository can be given. The location should be prefixed by the type of the repository (with a “+” in between) unless the location ends in “.git” in which case the prefix is optional.
Select a revision to operate on. Accepts any string that’s supported by the VCS system that manages the repository, which means you can provide branch names, tag names, exact revision ids, etc. This option is used in combination with the --find-revision-number, --find-revision-id and --export options.
If this option is not provided a default revision is selected: “last:1” for Bazaar repositories, “master” for git repositories and “default” (not “tip”!) for Mercurial repositories.
Select a release to operate on. This option works in the same way as the --revision option. Please refer to the vcs-repo-mgr documentation for details on “releases”.
Although release identifiers are based on branch or tag names they may not correspond literally, this is why the release identifier you specify here is translated to a global revision id before being passed to the VCS system.
|-n, --find-revision-number||Print the local revision number (an integer) of the revision given with the --revision option. Revision numbers are useful as a build number or when a simple, incrementing version number is required. Revision numbers should not be used to unambiguously refer to a revision (use revision ids for that instead). This option is used in combination with the --repository and --revision options.|
|-i, --find-revision-id||Print the global revision id (a string) of the revision given with the --revision option. Global revision ids are useful to unambiguously refer to a revision. This option is used in combination with the --repository and --revision options.|
|--list-releases||Print the identifiers of the releases in the repository given with the --repository option. The release identifiers are printed on standard output (one per line), ordered using natural order comparison.|
|--select-release=RELEASE_ID||Print the identifier of the newest release that is not newer than RELEASE_ID in the repository given with the --repository option. The release identifier is printed on standard output.|
Print the summed revision numbers of multiple repository/revision pairs. The repository/revision pairs are taken from the positional arguments to vcs-repo-mgr.
This is useful when you’re building a package based on revisions from multiple VCS repositories. By taking changes in all repositories into account when generating version numbers you can make sure that your version number is bumped with every single change.
|--vcs-control-field||Print a line containing a Debian control file field and value. The field name will be one of “Vcs-Bzr”, “Vcs-Hg” or “Vcs-Git”. The value will be the repository’s remote location and the selected revision (separated by a “#” character).|
|-u, --update||Create/update the local clone of a remote repository by pulling the latest changes from the remote repository. This option is used in combination with the --repository option.|
Merge a change into one or more release branches and the default branch.
By default merging starts from the current branch. You can explicitly select the branch where merging should start using the --rev, --revision and --release options.
You can also start by merging a feature branch into the selected release branch before merging the change up through later release branches and the default branch. To do so you pass the name of the feature branch as a positional argument.
If the feature branch is located in a different repository you can prefix the location of the repository to the name of the feature branch with a “#” token in between, to delimit the location from the branch name.
|-e, --export=DIRECTORY||Export the contents of a specific revision of a repository to a local directory. This option is used in combination with the --repository and --revision options.|
|-d, --find-directory||Print the absolute pathname of a local repository. This option is used in combination with the --repository option.|
|-v, --verbose||Increase logging verbosity (can be repeated).|
|-q, --quiet||Decrease logging verbosity (can be repeated).|
|-h, --help||Show this message and exit.|
The primary way to use the vcs-tool command requires you to create a configuration file:
$ cat > ~/.vcs-repo-mgr.ini << EOF [coloredlogs] type = git local = /tmp/coloredlogs remote = email@example.com:xolox/python-coloredlogs.git EOF
Because the -r, --repository option accepts remote repository locations in addition to names it’s not actually required to create a configuration file. Of course this depends on your use case(s).
Below are some examples of the command line interface. If you’re interested in using the Python API please refer to the online documentation.
If the configuration file defines a local and remote repository and the local repository doesn’t exist yet it will be created the first time you update it:
$ vcs-tool --repository coloredlogs --update 2014-05-04 18:55:54 INFO Creating Git clone of firstname.lastname@example.org:xolox/python-coloredlogs.git at /tmp/coloredlogs .. Cloning into bare repository '/tmp/coloredlogs'... remote: Reusing existing pack: 96, done. remote: Counting objects: 5, done. remote: Compressing objects: 100% (5/5), done. remote: Total 101 (delta 0), reused 0 (delta 0) Receiving objects: 100% (101/101), 28.11 KiB, done. Resolving deltas: 100% (44/44), done.
Later runs will pull the latest changes instead of performing a full clone:
$ vcs-tool --repository coloredlogs --update 2014-05-04 18:55:56 INFO Updating Git clone of email@example.com:xolox/python-coloredlogs.git at /tmp/coloredlogs .. From github.com:xolox/python-coloredlogs * branch HEAD -> FETCH_HEAD
Revision numbers are integer numbers that increment with every added revision. They’re very useful during packaging/deployment:
$ vcs-tool --repository coloredlogs --revision master --find-revision-number 24
Revision ids (hashes) are hexadecimal strings that uniquely identify revisions. They are useful to unambiguously refer to a revision and its history (e.g while building a package you can embed the revision id as a hint about the origins of the package):
$ vcs-tool --repository coloredlogs --revision master --find-revision-id bce75c1eea88ebd40135cd45de716fe9591e348c
By default the repositories created by vcs-repo-mgr do not contain a working tree, just the version control files (in Git terminology this is called a “bare repository”). This has two reasons:
- Bare repositories help conserve disk space. This is insignificant for small repositories, but on large repositories it can make a noticeable difference. Especially if you’re using a lot of them :-)
- Bare repositories enforce the principle that the working tree shouldn’t be
used during packaging (instead you should export the tree at a specific
revision to a temporary directory and use that). This insistence on not
using the working tree during packaging has two reasons:
- The working tree can contain files which are not under version control. Such files should certainly not be included in a package unintentionally.
- If the working tree of a repository is used, this makes it impossible to safely perform parallel builds from the same repository (the builds can corrupt each other’s working tree).
This means that if you want to do something with the files in the repository you have to export a revision to a (temporary) directory:
$ vcs-tool --repository coloredlogs --export /tmp/coloredlogs-snapshot 2014-05-04 19:17:24 INFO Exporting revision master of /tmp/coloredlogs to /tmp/coloredlogs-snapshot .. $ ls -l /tmp/coloredlogs-snapshot total 28K drwxrwxr-x 2 peter peter 4.0K May 3 14:31 coloredlogs drwxrwxr-x 3 peter peter 4.0K May 3 14:31 vim -rw-rw-r-- 1 peter peter 1.1K May 3 14:31 LICENSE.txt -rw-rw-r-- 1 peter peter 56 May 3 14:31 MANIFEST.in -rw-rw-r-- 1 peter peter 5.4K May 3 14:31 README.rst -rwxrwxr-x 1 peter peter 1.1K May 3 14:31 setup.py
This section is currently a “braindump” which means I haven’t committed to any of these improvements, I’m just thinking out loud ;-).
- Improve interactive repository selection
Two improvements for interactive usage of the vcs-tool program:
- Automatically load a repository’s configuration when a pathname is given that matches an entry in a configuration file (right now you need to give the repository’s name in order to load its configuration).
- Do the obvious thing when no repository is specified on the command line but the working directory matches a configured repository.
- Wildcard matching in configuration files
- It might be interesting to support shell wildcard matching against local directory names to apply a default configuration to a group of repositories?
- Enable more extensive customization
- Right now the version control commands are hard coded and not easy to customize for those cases where the existing API gets you 90% of where you want to be but makes that last 10% impossible. Technically this is already possible through subclassing, but a more lightweight solution would certainly be nice to have :-).
This section documents known issues that users may run into.
Bazaar and Mercurial are both written in Python and available on PyPI and as such I included them in the installation requirements of vcs-repo-mgr, because I couldn’t think of a good reason not to.
Adding support for Python 3 to vcs-repo-mgr made things more complicated because Bazaar and Mercurial didn’t support Python 3, leading to installation errors. To cope with this problem the Bazaar and Mercurial requirements were made conditional on the Python version:
- On Python 2 the Bazaar and Mercurial packages would be installed together with vcs-repo-mgr.
- On Python 3 the user was instead responsible for making sure that Bazaar and Mercurial were installed (for example using system packages).
This works fine because vcs-repo-mgr only invokes Bazaar and Mercurial using the command line interfaces so it doesn’t matter whether the version control system is using the same version of Python as vcs-repo-mgr.
Since then the installation of the Bazaar package has started failing on PyPy, unfortunately this time there is no reliable and backwards compatible way to make the Bazaar dependency optional in wheel distributions due to bugs in setuptools.
When I investigated support for environment markers that match Python implementations (refer to the link above) I decided that instead of writing a setup script full of nasty and fragile hacks I’d rather just drop official (tested) support for PyPy, as silly as the reason for it may be.
The latest version of vcs-repo-mgr is available on PyPI and GitHub. The documentation is hosted on Read the Docs and includes a changelog. For bug reports please create an issue on GitHub. If you have questions, suggestions, etc. feel free to send me an e-mail at firstname.lastname@example.org.
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