Why Can't You Specify Ubuntu and Centos in the Charm Series?

[zicklag]

Thanks @szeestraten, I hadn’t seen those yet.

@rick_h

We’ve had a policy that in order to encourage charms to be worked on as a group and that there’s enough differences (e.g. install commands are completely different and expected software versions like python versions are different enough) that best practice is to have split charms for different operating systems.

With the Lucky framework, the plan is to do one thing that is specific to the operating system, and that is to install Docker ( or maybe a different container engine ). Aside from that difference, the charm should run the same regardless of the distro because of the containerized application. That difference in how Docker is installed will be handled by the Lucky framework, automatically enforcing the best practice for how to install Docker and removing any platform specific code from the users charm.

Additionally, when it comes to Python support, if and when Lucky gets Python support, it will be designed so that Python is embedded in the Lucky framework itself and will have no dependency on the system Python version.

@rick_h

We haven’t had many charms in this category and if you’re ok with sharing the repo it’s at I’d be interested in looking at how the differences between OS’s are handled.

I think that the bigest reason that we have very few charms that can run on both distros is because there are no tools available for charm developers to write distro agnostic charms. Almost everything out there today is heavily dependent on tools like apt and python that don’t run on both distros, but by building on tools such as Docker or Snap, it should be perfectly possible to write distro agnostic charms with a perfect respect for the best practices.