Add App Container / Rocket Builder

[nchammas]

There is a new App Container specification.

The spec already has a few runtime implementations, the most prominent of which is Rocket, from the CoreOS team. Another implementation is jetpack.

If I understand correctly, the promise of the appc spec is that once you build an image according to that spec, any number of runtimes which implement the spec can run the image.

It would be great if Packer could build images according to this spec as well.

Given the App Container spec's early state, I understand this request may not be actionable for a while.

[kelseyhightower]

@nchammas I had a chat with @mitchellh about this during FOSDEM. I'm going to hack on this, expect a PR soon.

[kelseyhightower]

@mitchellh Let me know if you've already started working on this one.

[kelseyhightower]

The first open question I have is regarding the starting point for building an ACI. Currently there are no "base" ACIs for ubuntu, fedora, etc. We have a couple of options here:

• bootstrap the OS and run the provisioners in a chroot
• Use the host OS and package up the dirs that need to make up the final ACI.

I would love some community feedback here before I head down the wrong path.

[AntonioMeireles]

@kelseyhightower fwiw i 'd vote for the 1st option, for full reproducibility/reliability.

[rasschaert]

Another +1 for the first option.

[blalor]

+1

[blalor]

Bootstrapping is unfortunately rather distribution-dependent. For Fedora-based distributions, ami-creator (my fork) works well, and I use it for building base AMIs that are then fed into Packer. I'm also using it to build base ACIs. I believe there are similar tools for Debian-based distributions. It really would be nice to somehow have this built into Packer, but I understand that's a hard problem to solve. At a minimum, having an ACI builder that could take an image URL as a starting point would be useful.

[nchammas]

A lot has changed in this space since I first opened this issue. Is this still relevant?

[blalor]

I think it is. There's first-class support for Docker in Packer, so it'd be nice to see first-class support for building ACIs. acbuild exists today as a tool for building ACIs outside of Packer.

[mwhooker]

Happy to look at PRs, but this isn't something we're planning to implement for 1.0. Please see the mailing list for more details on 1.0.