Packaging Guide¶

Building packages with dh-virtualenv is relatively easy to start with, but it also supports lot of customization to match your specific needs.

By default, dh-virtualenv installs your packages under /opt/venvs/«packagename». The package name is provided by the debian/control file.

To use an alternative install prefix, add a line like the following to the top of your debian/rules file.

export DH_VIRTUALENV_INSTALL_ROOT=«/your/custom/install/dir»

dh_virtualenv will now use the value of DH_VIRTUALENV_INSTALL_ROOT instead of /opt/venvs when it constructs the install path.

To use an install suffix other than the package name, call dh_virtualenv using the --install-suffix command line option. See Advanced usage for further information on passing options.

Simple usecase¶

To signal debhelper to use dh-virtualenv for building your package, you need to pass --with python-virtualenv to the debhelper sequencer.

In a nutshell, the simplest debian/rules file to build using dh-virtualenv looks like this:

#!/usr/bin/make -f

%:
        dh $@ --with python-virtualenv

However, the tool makes a few assumptions of your project’s structure:

For installing requirements, you need to have a file called requirements.txt in the root directory of your project. The requirements file is not mandatory.

The project must have a setup.py file in the root of the project. dh_virtualenv will run setup.py install to add your project to the virtualenv.

After these preparations, you can just build the package with your favorite tool!

Environment variables¶

Certain environment variables can be used to customise the behaviour of the debhelper sequencer in addition to the standard debhelper variables.

DH_VIRTUALENV_INSTALL_ROOT¶: Define a custom root location to install your package(s). The resulting location for a specific package will be $DH_VIRTUALENV_INSTALL_ROOT/«<packagename», unless --install-suffix is also used to change «<packagename».

Command line options¶

To change its default behavior, the dh_virtualenv command accepts a few command line options:

-p <package>, --package <package>¶: Act on the package named <package>.

-N <package>, --no-package <package>¶: Do not act on the specified package.

-v, --verbose¶: Turn on verbose mode. This has a few effects: it sets the root logger level to DEBUG, and passes the verbose flag to pip when installing packages. This can also be provided using the standard DH_VERBOSE environment variable.

--install-suffix <suffix>¶: Override virtualenv installation suffix. The suffix is appended to /opt/venvs, or the DH_VIRTUALENV_INSTALL_ROOT environment variable if specified, to construct the installation path.

--extra-index-url <url>¶: Use extra index url <url> when running pip to install packages. This can be provided multiple times to pass multiple URLs to pip. A common use-case is enabling a private Python package repository.

--preinstall <package>¶: Package to install before processing the requirements. This flag can be used to provide a package that is installed by pip before processing the requirements file. It is handy if you need to install a custom setup script or other packages needed to parse setup.py, and can be provided multiple times to pass multiple packages for pre-install.

--extras <name>¶: New in version 1.1.

Name of extras defined in the main package (specifically its setup.py, in extras_require). You can pass this multiple times to add different extra requirements.

--pip-tool <exename>¶: Executable that will be used to install requirements after the preinstall stage. Usually you’ll install this program by using the --preinstall argument. The replacement is expected to be found in the virtualenv’s bin/ directory.

--upgrade-pip¶

New in version 1.0.

Force upgrading to the latest available release of pip. This is the first thing done in the pre-install stage, and uses a separate pip call.

Options provided via --extra-pip-arg are ignored here, because the default pip of your system might not support them (since version 1.1).

Note: This can produce non-repeatable builds. See also --upgrade-pip-to.

--upgrade-pip-to <VERSION>¶

New in version 1.2.

Same as --upgrade-pip, but install an explicitly provided version. You can specify latest to get the exact same behaviour as with the simple option.

Note: This can be used for more repeatable builds that do not have the risk of breaking on a new pip release.

--index-url <URL>¶: Base URL of the PyPI server. This flag can be used to pass in a custom URL to a PyPI mirror. It’s useful if you have an internal PyPI mirror, or you run a special instance that only exposes selected packages of PyPI. If this is not provided, the default will be whatever pip uses as default (usually the API of https://pypi.org/).

--extra-pip-arg <PIP ARG>¶

Extra arguments to pass to the pip executable. This is useful if you need to change the behaviour of pip during the packaging process. You can use this flag multiple times to pass in different pip flags.

As an example, adding --extra-pip-arg --no-compile in the call of a override_dh_virtualenv rule in the debian/rules file will disable the generation of *.pyc files.

--extra-virtualenv-arg <VIRTUALENV ARG>¶: Extra parameters to pass to the virtualenv executable. This is useful if you need to change the behaviour of virtualenv during the packaging process. You can use this flag multiple times to pass in different virtualenv flags.

--requirements <REQUIREMENTS FILE>¶: Use a different requirements file when installing. Some packages such as pbr expect the requirements.txt file to be a simple list of requirements that can be copied verbatim into the install_requires list. This command option allows specifying a different requirements.txt file that may include pip specific flags such as -i, -r- and -e.

--setuptools¶: Use setuptools instead of distribute in the virtualenv.

--setuptools-test¶: New in version 1.0.

Run python setup.py test when building the package. This was the old default behaviour before version 1.0. This option is incompatible with the deprecated --no-test.

--python <path>¶: Use a specific Python interpreter found in path as the interpreter for the virtualenv. Default is to use the system default, usually /usr/bin/python.

--builtin-venv¶: Enable the use of the build-in venv module, i.e. use python -m venv to create the virtualenv. It will only work with Python 3.4 or later, e.g. by using the option --python /usr/bin/python3.4.

-S, --use-system-packages¶: Enable the use of system site-packages in the created virtualenv by passing the --system-site-packages flag to virtualenv.

--skip-install¶

Skip running pip install . after dependencies have been installed. This will result in anything specified in setup.py being ignored. If this package is intended to install a virtualenv and a program that uses the supplied virtualenv, it is up to the user to ensure that if setup.py exists, any installation logic or dependencies contained therein are handled.

This option is useful for web application deployments, where the package’s virtual environment merely supports an application installed via other means. Typically, the debian/«packagename».install file is used to place the application at a location outside of the virtual environment.

--pypi-url <URL>¶: Deprecated since version 1.0: Use --index-url instead.

--no-test¶: Deprecated since version 1.0: This option has no effect. See --setuptools-test.

Advanced usage¶

To provide command line options to the dh_virtualenv step, use debhelper’s override mechanism.

The following debian/rules will provide http://example.com as an additional source of Python packages:

#!/usr/bin/make -f

%:
        dh $@ --with python-virtualenv

override_dh_virtualenv:
        dh_virtualenv --extra-index-url http://example.com

pbuilder and dh-virtualenv¶

Building your Debian package in a pbuilder environment can help to ensure proper dependencies and repeatable builds. However, precisely because pbuilder creates its own build environment, build failues can be much more difficult to understand and troubleshoot. This is especially true when there is a pip error inside the pbuilder environment. For that reason, make sure that you can build your Debian package successfully outside of a pbuilder environment before trying to build it inside.

With those caveats, here are some tips for making pip and dh_virtual work inside pbuilder.

If you want pip to retrieve packages from the network, you need to add USENETWORK=yes to your /etc/pbuilderrc or ~/.pbuilderrc file.

pip has several options that can be used to make it more compatible with pbuilder.

Use --no-cache-dir to stop creating wheels in your home directory, which will fail when running in a pbuilder environment, because pbuilder sets the HOME environment variable to “/nonexistent”.

Use --no-deps to make pip builds more repeatable.

Use --ignore-installed to ensure that pip installs every package in requirements.txt in the virtualenv. This option is especially important if you are using the –system-site-packages option in your virtualenv.

Here’s an example of how to use these arguments in your rules file.

override_dh_virtualenv:
        dh_virtualenv \
        --extra-pip-arg "--ignore-installed" \
        --extra-pip-arg "--no-deps" \
        --extra-pip-arg "--no-cache-dir"

Experimental buildsystem support¶

Important

This section describes a completely experimental functionality of dh-virtualenv.

Starting with version 0.9 of dh-virtualenv, there is a buildsystem alternative. The main difference in use is that instead of the --with python-virtualenv option, --buildsystem=dh_virtualenv is passed to debhelper. The debian rules file should look like this:

#!/usr/bin/make -f

%:
        dh $@ --buildsystem=dh_virtualenv

Using the buildsystem instead of the part of the sequence (in other words, instead of the --with python-virtualenv) one can get more flexibility into the build process.

Flexibility comes from the fact that buildsystem will have individual steps for configure, build, test and install and those can be overridden by adding override_dh_auto_<STEP> target into the debian/rules file. For example:

#!/usr/bin/make -f

%:
        dh $@ --buildsystem=dh_virtualenv

override_dh_auto_test:
        py.test test/

In addition the separation of build and install steps makes it possible to use debian/install files to include built files into the Debian package. This is not possible with the sequencer addition.

The build system honors the DH_VIRTUALENV_INSTALL_ROOT environment variable. Following other environment variables can be used to customise the functionality:

DH_VIRTUALENV_ARGUMENTS¶

Pass given extra arguments to the virtualenv command

For example:

export DH_VIRTUALENV_ARGUMENTS="--no-site-packages --always-copy"

The default is to create the virtual environment with --no-site-packages.

DH_VIRTUALENV_INSTALL_SUFFIX¶

Override the default virtualenv name, instead of source package name.

For example:

DH_REQUIREMENTS_FILE¶: New in version 1.0.

Override the location of requirements file. See --requirements.

DH_UPGRADE_PIP¶: New in version 1.0.

Force upgrade of the pip tool by setting DH_UPGRADE_PIP to empty (latest version) or specific version. For example:

DH_UPGRADE_SETUPTOOLS¶: New in version 1.0.

Force upgrade of setuptools by setting DH_UPGRADE_SETUPTOOLS to empty (latest version) or specific version.

DH_UPGRADE_WHEEL¶: New in version 1.0.

Force upgrade of wheel by setting DH_UPGRADE_WHEEL to empty (latest version) or specific version.

DH_PIP_EXTRA_ARGS¶

New in version 1.0.

Pass additional parameters to the pip command. For example:

export DH_PIP_EXTRA_ARGS="--no-index --find-links=./requirements/wheels"