WIP - initial gentoo support (should fix #19)

[javierbertoli]

This Dockerfile 'kinda' worked locally for 2019.2.2. Still needs more work to add the other versions.

[myii]

@mgomersbach Would you mind casting an eye over this PR with your recommendations?

[myii]

We should avoid this.

• Found the solution here, i.e.

  • echo 'ACCEPT_KEYWORDS="~amd64"' | tee -a /etc/portage/make.conf

Yeah, common pitfall, and a logical one too, however, from now entire "world" (all system packages + your installed packages) will now use the unstable branch (amd64 == stable / ~amd64 == unstable) and force an awful lot of rebuilds, if the package manager even is able to resolve it.

Replacing it with something based on:

• https://wiki.gentoo.org/wiki/Knowledge_Base:Accepting_a_keyword_for_a_single_package#Manual_resolution

Perhaps:

Suggested change

	RUN echo 'ACCEPT_KEYWORDS="~amd64"' | tee -a /etc/portage/make.conf
	RUN mkdir --p /etc/portage
	RUN echo "=app-admin/salt ~amd64" >> /etc/portage/package.accept_keywords

• Probably don't need the mkdir --p /etc/portage but just taking that from the referenced wiki page

[mgomersbach]

You are right, you should not need it, but it doesn't hurt either. However it could cover up a case where it is not available (which it should, because for example the system profile is defined/linked in there)
Rest looks fine.

[myii]

This comment is useful: #19 (comment).

[mgomersbach]

I think you should skip updating @System or @world.
We want to test salt and not gentoo and it is a bit of a anti pattern in docker.

[mgomersbach]

Unless the bootstrap script supports gentoo well, I'd use portage/emerge itself to install salt.