@ericmj I haven't finished all of the changes yet, but pushed up some of the changes you requested. I'm not quite sure how much I like a OSVersions.select_os_versions(tags) function. Mostly because then that would imply that we would only call out to OSVersions to get a single OS versions, and not all of them. Feels odd to me to group together the other OS's in another file, though I'm not strictly opposed. Let me know what you think of this, and I'll look to finish this up once I get some more time to work on this.

I am not sure I follow, why do you need to move it to another file? Right now only alpine is looked up so that's only what you have to test, if ubuntu/debian is added in the future that could be tested as well, possibly by changing the API to select_os_versions("alpine", tags) or select_os_versions(%{"alpine" => tags, "ubuntu" => tags}).

If you would rather mock then please use https://hex.pm/packages/mox instead and create a behaviour for Bob.DockerHub.

Sorry for the delay, finally got some time to work on this again. What I meant by needing to move it to another file, is that then you'd need to move Bob.DockerHub.fetch_repo_tags("library/alpine") into the calling file, and that feels wrong to me, since that feels like its part of the responsibility of the OSVersions file (if we did do this, then a better name would be something like OSFilterer). I think maybe the easiest way forward would be to move most of what is currently in OSVersions into a new file OSVersionsSelector and then OSVersions just gets the tags and then gives them to OSVersionsSelector to filter them. Then we can only test OSVersionsSelector without having to mock.

@ericmj this is ready to be reviewed again

To me it's fine to have public functions in a module even it's only to test them. Personally I would merge OSVersions and OSVersionsSelector, but this is also fine.

Thank you for the PR!

Is this ready to be merged? Alpine 3.14.1 has been released and I'm keen to bump our images.

@ericmj any reason to not merge this?

@ericmj can we merge this? I see that Alpine 3.14.1 and Alpine 3.14.2 have been released and it would be nice to have the next Erlang and Elixir releases to use those newer Alpine versions.

Adding this change would increase the maintenance burden too much since Alpine often make breaking changes. Instead please submit PRs with version updates and the required changes to bob or build logs that show that new versions are compatible with the old.