Add version to docker-images

[domire8]

As title suggests. Best option would be a workflow that updates the version on push to main.

[domire8]

comment from @eeberhard

As a side note, how do you feel about tagging the ros2-control image with the version (for example, as :iron and :iron-3.18)? That way if we keep iron but upgrade ros2_control to some other version later, we can distinguish them. Not in scope for this PR but goes in a similar direction and I think would be useful to do.

comment from @LouisBrunner

I think we should just make our own version for this. e.g. v2.3.0+iron

comment from me:

Fair suggestion, do we take the version from a VERSION file?

[LouisBrunner]

I don't mind where we get the version at the moment, as long as we produce 2 tags (v2.3.0+iron and v2.3.0, as it makes package management easier later). I don't mind which of these tags is the ones that makes it into git either.

[domire8]

But then how we deal with v2.3.1+iron and v2.3.1+humble? I guess that wouldnt be possible anymore? Or humble has major 1 where iron has major 2?

[LouisBrunner]

Iron and humble would be different versions, e.g. v1.4.5+humble and v2.3.1+iron. There is no reason for them to be linked (after all they aren't necessarily compatible).

[domire8]

A couple of weeks ago, we decided that in the near future, we'll drop the ros2-control image and only ship one ros2-ws image that contains all dependencies we need for ROS2 and ROS2 Control. @LouisBrunner What would be your suggestion for the tags of the image? vX.Y.Z+ROS_DISTRO? I think we could already start to set that up.

[LouisBrunner]

So the new ros2-ws will be equivalent to the old ros2-control?

Yeah I think a version like that makes sense.

[domire8]

Name is not 100% sure but yeah essentially that's it.

[domire8]

The + is not allowed in docker images tags though it seems

[LouisBrunner]

Ah, that's a shame. I guess we can do multi-tags and include vX.Y.Z, vX.Y.Z-ROS_DISTRO and ROS_DISTRO and that should be both standard Docker and mostly semver-compliant.