(refactor): optimize Dockerfiles, parallel build process

[traktuner]

Changes in this PR:

-) Used new jlesage/baseimage-gui v4 (the image without version tag is not maintained anymore)
-) the Dockerfiles are synchronized now (only difference is the used baseimage)
-) the images now get built in parallel with GitHub Actions*

*) please add a new GitGub actions variable DOCKERHUB_USER to your repo with your username before merging. I wanted to test the build and so I had to use variables instead of a hard coded username 😉

[traktuner]

@JonathanTreffler If you're interested, I'd be happy if you could test those changes.
I can also add a Dockerfile with the newly released ubuntu-22 baseimage from jlesage. Already tested it myself.
Please let me know - thanks 😊

[JonathanTreffler]

Thank you for the PR :)

I will review the rest, but before that a small note:

-) a new APP_ICON was added

The reason the existing APP_ICON code is commented out is, that I do not have any rights to Backblaze's Logo and I have no idea if I would be allowed to include it in the Docker Image. And I just don't think it is important enough to risk legal trouble :)

If you could please take out the APP_ICON from the PR, that would be nice, otherwise I will just merge it as is and remove it on my main branch. Thx :)

[traktuner]

Ah got it - thanks :)
I removed the icon!
The checks are currently failing because of the missing DOCKERHUB_USER GitHub actions variable (I needed those to test the build in my environment).

[JonathanTreffler]

I can also add a Dockerfile with the newly released ubuntu-22 baseimage from jlesage. Already tested it myself.

That would be great, thank you :)

I think with all the weird "needing ubuntu 18 for some reason on some devices, nobody knows why" stuff it would be good to stick with ubuntu 20 as the base for the latest image tag for now, but adding the v22 as an extra (non-versioned) tag like ubuntu18 would be great, so people can test it out and give feedback, before we migrate everybody else on latest over to it.

[traktuner]

Sure, I will do that in a separate PR!
I was one of those "need ubuntu18" users :D
With ubuntu20, a connection to backblaze was not possible. But it seems that some Synology DSM updates fixed things, now ubuntu20 and the ubuntu22 images work great!

[JonathanTreffler]

The checks are currently failing because of the missing DOCKERHUB_USER GitHub actions variable (I needed those to test the build in my environment).

I already added the env and restarted the action, but they are not used here and the docs explain why:

Anyone with collaborator access to this repository can use these secrets and variables for actions. They are not passed to workflows that are triggered by a pull request from a fork.

I invited you to be a repository collaborator, so you can develop from a branch instead of a fork if you want :)

[JonathanTreffler]

LGTM :)

[JonathanTreffler]

I reviewed it so now all prerequisites for a merge should be fullfilled, you should be able to merge it yourself :)

[JonathanTreffler]

The new actions worked beautifully, the main and ubuntu18 branches are updated and the latest and versioned branches should get updated with the next versioned release.