Add sabayon support and new features

[geaaru]

Features added:

• environment variables configuration from image files
• repositories handler
• docker http sourcer

[stgraber]

Hi, you'll need to make sure all your commits include the needed Signed-off-by line in their message, making that DCO check happy. Until then, we can't really look at those changes.

[geaaru]

In my fork i added also Gopkg.toml/lock for handle dependencies through dep tool. I think that it's useful for trace versions of vendors used. WDYT ?

[stgraber]

We usually try to stay away from dependency managers both in LXD and distrobuilder, instead preferring to rely on external packages that have a good track record of not breaking their API and switching away from any which breaks it.

[stgraber]

@monstermunchkin can you spend a bit of time to review this please?

[geaaru]

I'm not agree with this because in general there is always a tools and/or api that could be change in time and have a tool that identify what is right version to use for compilation (also for gentoo stuff) could be helpful.
However, np. Thanks for clarification.

[monstermunchkin]

I don't understand the necessity of the repository actions. Can't all of that just be handled with the existing actions?

[geaaru]

About repositories attributes.... i think that it's more clear define custom repositories to a specific section instead of create pre/post actions, so inside specific distro package manager tool could be create a specific implementation related to distro. More clear image.yaml.

We could also remove AptSources from
https://github.com/lxc/distrobuilder/blob/master/shared/definition.go#L52
if it is implements to apt manager.

imho

[monstermunchkin]

I still don't see the point of having the repo handler. You could just simply run enman add community or equo enable sabayonlinux.org in post-unpack.

[geaaru]

About repository I think that reason could be the same of why exists a packages section.
For apt, emerge and any others module for manage packages inside a specific distro could be handle with post-unpack action.

It's better have a clear image files that a poor image files with a list of list of actions for any type of operations.

I simply follow what is been shared with stgraber on irc channel.

[monstermunchkin]

This branch needs to be rebased. Also, could you please implement the repo thing as discussed on IRC? (https://paste.ubuntu.com/p/7PT2BTDYjQ/)

[geaaru]

yeah, of course. I will modify code as discussed.
Let me only some days because i'm in holiday.

Thanks

[monstermunchkin]

Please run make check and fix the issues. Golint is complaining about some things. Other than that the code looks good to me.

[monstermunchkin]

Thanks for your contributions!