catkin_virtualenv

This package provides a mechanism to:

• export python pip requirements via package.xml.
• bundle a virtualenv within a catkin package, inheriting requirements from any dependencies.
• wrap python scripts and tests in a catkin package with a virtualenv loader.
• change which interpreter is used for executing scripts and tests (i.e. python2, python3, pypy, etc.)

At build time, CMake macros provided by this package will create a virtualenv inside the devel space, and create wrapper scripts for any Python scripts in the package. Both will be included in any associated bloom artifacts.

This library is GPL licensed due to the inclusion of dh_virtualenv.

Compatibility:

• Python 3.7+
• Ubuntu 20.04+, maybe others
• ROS Noetic, maybe others
• catkin-tools, colcon, catkin_make_isolated (i.e. ros_buildfarm), but not catkin_make

For general help, please check the FAQ. Report bugs on the issue tracker.

Exporting python requirements

A package containing python modules with external pip dependencies should define a requirements.txt:

GitPython==2.1
psutil==5.2.2

Add an export to package.xml:

<export>
  <pip_requirements>requirements.txt</pip_requirements>
</export>

Make sure to install the requirements file in CMakeLists.txt:

install(FILES requirements.txt
  DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION})

If a catkin package exports dependencies in a requirements.txt file, any dependent catkin package that bundles a virtualenv (see below) will inherit those dependencies.

Bundling virtualenv

It’s possible to bundle all of a catkin package’s python requirements, as well as those of its catkin dependencies, into a virtualenv. This process will also override the standard catkin_install_python macro to wrap a virtualenv loader around the specified python scripts.

Add an build dependency on catkin_virtualenv to package.xml, as well as on any library packages you may want. Traditionally

<build_depend>catkin_virtualenv</build_depend>

<!-- In a catkin/python world, this would normally be an exec_depend. However, if `some_python_library` exports
requirements.in, it needs to be pulled in at build time as well -->
<depend>some_python_library</depend>

In CMakeLists.txt:

# Make sure to find-package `catkin_virtualenv`
find_package(catkin REQUIRED ... catkin_virtualenv ...)

# Generate the virtualenv
catkin_generate_virtualenv()

# Make sure your python executables are installed using `catkin_install_python`:
catkin_install_python(
  PROGRAMS
    scripts/do_python_things
  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION})

Departing from convention, scripts/do_python_things should not be executable, and catkin build will warn to that effect. This package works by hijacking catkin_install_python to generate new wrapper scripts into the devel and install space, which bootstrap the virtualenv. In addition, rosrun gets confused if there’s two executable files with the same name.

Unit and integration tests will automatically pick up the virtualenv as well. The only change is to add a dependency from the test target to the virtualenv target:

if(CATKIN_ENABLE_TESTING)

  # nosetests
  catkin_add_nosetests(test
    DEPENDENCIES ${PROJECT_NAME}_generate_virtualenv
  )

  # rostests
  catkin_install_python(
    PROGRAMS
      test/test_script
    DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION})

  add_rostest(test/run_test_script.test
    DEPENDENCIES ${PROJECT_NAME}_generate_virtualenv
  )
)

Additional CMake Options

The following options are supported by catkin_generate_virtualenv():

catkin_generate_virtualenv(
  # Specify the input requirements for this package that catkin_virtualenv will automatically lock.
  INPUT_REQUIREMENTS requirements.in

  # Select an alternative python interpreter - it must be installed on the system.
  PYTHON_INTERPRETER python3.7  # Default python3

  # Choose not to use underlying system packages. This excludes any python packages installed by apt or system-pip from the environment.
  USE_SYSTEM_PACKAGES FALSE  # Default TRUE

  # Disable including pip requirements from catkin dependencies of this package.
  ISOLATE_REQUIREMENTS TRUE  # Default FALSE
  # Note: due to https://github.com/nose-devs/nose/issues/1099 and nose being unmaintained, using this option will prevent catkin_add_nosetests from working.
  # Hence CATKIN_IGNORE in the test_catkin_virtualenv_isolated package. `nose-py3` seems to be a decent stopgap if used to replace `nose` in `catkin_virtualenv/requirements.txt`
  # but https://github.com/atsb/nose-py3/issues/9 is currently a show-stopper.

  # Disable creating a unit test to verify that package requirements are locked.
  CHECK_VENV FALSE  # Default TRUE

  # Disable renaming the process names to hide the interpreter name, this has can create issues when executing the process as root.
  RENAME_PROCESS FALSE # Default TRUE

  # Provide extra arguments to the underlying pip invocation
  EXTRA_PIP_ARGS
    --no-binary=:all:
    -vvv
)

Locking dependencies

This project allows you to lock dependencies by leveraging pip-compile. This is optional, but will prevent your python projects from spontaneously combusting in the future!

Instead of managing a requirements.txt file, you will manage a requirements.in file, and catkin_virtualenv will generate the requirements.txt file for you upon build.

Create a requirements.in file and populate it manually with your package’s requirements. For example:

GitPython>=2
psutil

The file specified in CMake options as INPUT_REQUIREMENTS will be used to generate a locked requirements.txt at build time. You should check both requirements.in and requirements.txt in with your sources!

To regenerate the requirements.txt file, either delete it and rebuild the project, or run this command from your project directory:

catkin build --this --no-deps --catkin-make-args <PROJECT_NAME>_venv_lock where <PROJECT_NAME> is the name for the project as specified in the package’s CMakeLists.txt.

Alternatively, you can specify the package name catkin build <PACKAGE_NAME> --no-deps --catkin-make-args <PROJECT_NAME>_venv_lock

To migrate a package from catkin_virtualenv <=0.5 to use lock files:

• Rename requirements.txt to requirements.in
• Relax the version requirements in requirements.in as much as sensibly possible. eg. requests>=2 vs. requests=2.23.0
• Add INPUT_REQUIREMENTS requirements.in to catkin_generate_virtualenv() in CMakeLists.txt
• Build and test that the package given the installed dependency versions might have changed slightly
• Commit the new requirements.in, your updated CMakeLists.txt and the new version of requirements.txt and push changes

See example: https://github.com/locusrobotics/aiorospy/pull/30/commits/839b17adbe0c672f5e0d9cca702d12e16b117bca