Developer’s Guide

Python API reference

In progress, please see Python API.

REP 114: rospkg standalone library

The rosdep library is being developed using the ROS REP process. It is necessary to be familiar with these REPs in order to make sure that rosdep continues to follow the relevant specifications.

Bug reports and feature requests

Getting the code

The rosdep codebase is hosted on GitHub. To get started contributing patches, please create a fork:

Supporting a new OS/package manager

Adding new platforms to rosdep can be separated into two steps: adding support for a new package manager, and adding support for a new OS.

NOTE: There are numerous examples in rosdep2.platforms that you can follow.

Declaring a new OS

Adding support for a new OS is fairly straightforward: you just have to provide rosdep2 the keys that are associated with your OS and the keys of the installers that your OS supports.

Implementations must provide a register_platforms(context) call which sets up the keys used for the OS and package managers. The registration only sets up associated keys – it does not specify the implementation. OS keys should be pulled from rospkg.os_detect if they are available.

This example registers the gentoo OS and adds support for the equery and source package managers. It then sets the default package manager to equery:

from rospkg.os_detect import OS_GENTOO
def register_platforms(context):
    context.add_os_installer_key(OS_GENTOO, EQUERY_INSTALLER)
    context.add_os_installer_key(OS_GENTOO, SOURCE_INSTALLER)
    context.set_default_os_installer_key(OS_GENTOO, EQUERY_INSTALLER)

Declaring a new installer

A new installer is registered with the system using a register_installers(context) call. This call aqssociates the installer key with an implementation.

This example declares that pip is implemented using the PipInstaller() class. We also declare the PIP_INSTALLER variable so that other code can use it symbolically.:

def register_installers(context):
    context.set_installer(PIP_INSTALLER, PipInstaller())

Most installers are implemented using the the PackageManagerInstaller API. The following is the implementation of the PipInstaller:

class PipInstaller(PackageManagerInstaller):

    def __init__(self):
        super(PipInstaller, self).__init__(pip_detect, supports_depends=True)

    def get_install_command(self, resolved, interactive=True, reinstall=False):
        if not is_pip_installed():
            raise InstallFailed((PIP_INSTALLER, "pip is not installed"))
        # convenience function that calls outs to our detect function
        packages = self.get_packages_to_install(resolved, reinstall=reinstall)
        if not packages:
            return []
            return [['sudo', 'pip', 'install', '-U', p] for p in packages]

The pattern is fairly simple to implement for other package managers. You must provide a detect_function(package_names) (e.g. pip_detect()) that returns a list of package names that are already installed. You must also implement get_install_command() which must return a list of commands to execute in order to install the relevant packages.


If you contribute a support for a new OS/package manager, you must provide complete unit test coverage. For example, if your detector relies on parsing the output of a package manager, you must submit example output along with tests that parse them correctly.

Test files for os detection should be placed in test/os_name.


pip install pytest
pip install mock

rosdep2 uses pytest for testing, which is a fairly simple and straightfoward test framework. You just have to write a function start with the name test and use normal assert statements for your tests.

rosdep2 also uses mock to create mocks for testing on Python versions prior to 3.3.

You can run the tests, including coverage, as follows:

cd rosdep2/test


Sphinx is used to provide API documentation for rospkg. The documents are stored in the doc subdirectory.

In order to build the docs, you need the ‘ros-theme’, which should be stored in ~/sphinx/ros-theme. You can get a copy of ros-theme from: