CI for Focal and Jammy

[sloretz]

@chapulina this is what I had in mind for CI. I'm a bit weak on github actions so there may be syntax errors here. It uses some actions from https://github.com/ros-tooling/setup-ros

[sloretz]

I completly spaced that we can't really test sdformat_urdf on the ros2 branch builds on Focal because it would mean building all the ROS dependencies from source. My intent is this PR creates CI such that:

• On galactic branch test SDFormat 9-12 using ROS Galactic
• On ros2 branch test SDFormat 12 using ROS Humble and ROS Rolling

[sloretz]

LGTM - that is CI fails where I would expect it to (failing to find SDFormat9 on Jammy). Adding the GAZEBO_VERSION logic and support for sdformat12 should fix it.

[chapulina]

Cool, I've never used actions from setup-ros because I usually need to inject custom logic, such as pulling packages from packages.osrfoundation.org, or skipping unknown rosdep keys. I wonder how it will handle the conditions on package.xml when it invokes rosdep. It will be great if it just works!

[chapulina]

Have you checked that this will work for the galactic branch even if it's merged into the ros2 branch?

In case it only works when it's backported to galactic, I'd argue that it's best not to add galactic CI information to the ros2 branch. Instead, you could give the yaml file a generic name, like ci.yaml, and modify it according to the branch. This also helps comparing it across branches, for example:

gazebosim/ros_gz@galactic...ros2#diff-7c3faec84b8df09639159898858a4155d55a7febe4d37a6700f26fb6bef9826e

[sloretz]

I updated the PR to have a generic name ci.yaml, but I don't have a specific commit with the change since I rebased and squashed to add the sign-off.

[chapulina]

Thanks for iterating. It looks like this should work, we'll know once the rosdep key and the source code changes from #9 are in.