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:

```cmake if(CATKIN_ENABLE_TESTING)

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

# rostests

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