Launch ros_gz_bridge from xml

[caguero]

🎉 New feature

Part of #552

Summary

This patch allows to run the ros_gz bridge as an executable or as a composable node from an XML file.

How to test it?

Use the provided ros_gz_bridge.launch (modify config_file accordingly) to run the bridge as an executable

ros2 launch ros_gz_bridge ros_gz_bridge.launch config_file:=/home/caguero/ros_gz_ws/src/ros_gz/ros_gz_bridge/test/config/full.yaml

Verify that you see the /ros_chatter topic:

caguero@cold:~/ros_gz_ws$ ros2 topic list
/parameter_events
/ros_chatter
/rosout

And confirm that no container has been created:

caguero@cold:~/ros_gz_ws$ ros2 component list

Now CTRL-C the bridge and try the composable version:

 ros2 launch ros_gz_bridge ros_gz_bridge.launch config_file:=/home/caguero/ros_gz_ws/src/ros_gz/ros_gz_bridge/test/config/full.yaml use_composition:=True

Verify that you see the /ros_chatter topic:

caguero@cold:~/ros_gz_ws$ ros2 topic list
/parameter_events
/ros_chatter
/rosout

And confirm that a container has been created:

caguero@cold:~/ros_gz_ws$ ros2 component list
/ros_gz_container
  1  /ros_gz_bridge

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[azeey]

All of these parameters are optional in ros_gz_bridge.launch.py right? Can we do the same here?

Here's an example: https://github.com/ros2/launch_ros/blob/2bf4e6057dea57669c19395f6f39d390bd420ee7/launch_ros/launch_ros/actions/node.py#L121-L129

[caguero]

Done in 0bfc81d.

[azeey]

Looks very nice!! 🎉

[azeey]

LGTM!