lxc-template: make runnable by unprivileged users

[ghost]

lxc-template needlessly require root privileges in two places:

1. lock file location for flock
2. failing on tar failure during rootfs extraction

For flock, it's not necessary that the lock file be in /var/lock, it
can be anywhere. Why not put it in LXC_PATH?

For the failing tar thing, that's because some device are created with
mknod which unprivileged users can't do. These device, however, are
not necessary for the container to run well. We can ignore tar's error
exit code.

I replaced the exist code check by a check for the existence of
/bin/true in rootfs. I think that it's a good indication of whether
the rootfs was extracted.

Why am I making this change? Because I'd like to add support for
unprivileged containers in vagrant-lxc but it's kind of a big change
to make at once, so I thought I'd go incrementally.

[fgrehm]

hey @hsoft! the project hasn't had a new release in over a year now. @ccope was helping out for a bit but I'm not sure he's still up for maintaining the project.

Having support for unprivileged users would be great and I'd be up for giving u the permissions you need to keep the project going. WDYT? :)

[ghost]

@fgrehm I would be happy to "keep the fire burning" as you so eloquently said in #375

I understand that you've moved to something else and I don't want to use too much of your time, but would you mind giving me high-level reviews on some design decisions I'll have to take?

Example: I'm in the process of replacing the current lxc-attach way of fetching container IP with lxc-info -iH and bump lxc requirement to v1.0+ (I doubt that anyone still use pre v1 lxc). Code-wise, I think I can manage, but I would appreciate if you could tell me something like "good idea, I don't see how it could go wrong".

If you agree, then I'd assign you to PRs, with the understanding that you'd provide high-level-only thumbs up.

[ghost]

As I look at the active PRs and issues in the project, I'll have to put the unprivileged containers feature on the back-burner anyway because there's a lot of high-priority issues that need attending to.

I'm guessing that after having gone through these issues, my understanding of the project will be good enough so I won't need hand holding.

Ok, I can do this. Whenever you're ready.

[fgrehm]

I understand that you've moved to something else and I don't want to use too much of your time, but would you mind giving me high-level reviews on some design decisions I'll have to take?
If you agree, then I'd assign you to PRs, with the understanding that you'd provide high-level-only thumbs up.

Sounds good to me!

As I look at the active PRs and issues in the project, I'll have to put the unprivileged containers feature on the back-burner anyway because there's a lot of high-priority issues that need attending to.

Makes sense!

Ok, I can do this. Whenever you're ready.

Invited you as a collaborator :D

[fgrehm]

And BTW, I'm totally fine with dropping support for LXC < 1.0 🤘

[ghost]

@fgrehm critical PRs were processed and we'd be ready for a v1.2.4. Do you prefer to publish vagrant-lxc to rubygems yourself? Otherwise, my username on rubygems is hsoft.

[fgrehm]

@hsoft tks! please open up a PR with the prep for the release with changelog update + version bump and tag me in it. I'm going to try to put up automated rubygems release through travis this week and if I can't get it done will just give u permissions there as well 🍺