[Lxc-users] lxc-execute-ephemeral?

[Serge Hallyn]

Quoting Dan Kegel (dank at kegel.com):
> I'm configuring a buildbot for projects that (alas) are using
> .deb packages for their internal build dependencies,
> and the build & test script for the project does stuff like
>    sudo apt-get install foo
>    make
>    make test
>    sudo dpkg -r foo
> So I'm looking at chroots or lxc along with aufs or overlayfs to
> get a fresh build container every time.  I could stand a second
> of overhead per build, which is what lxc-execute seems to have.
> 
> I see there's a handy lxc-start-ephemeral script in ubuntu
> which uses aufs or overlayfs to create an ephemeral container
> that goes away when you stop it, but I was hoping to avoid
> having separate steps for creating/starting the container,
> running a command in it, and destroying it.
> 
> It seems like a very small leap from lxc-start-ephemeral to
> lxc-execute-ephemeral.
> Has anyone tried writing one?

Is your main objection the extra time it takes for the distro-provided
init to run over lxc-init, or using separate commands as you mention
above?  lxc-start-ephemeral takes arguments to execute, so you can
just do

  lxc-start-ephemeral -o q1 -- ps -ef

which will create the container, run the command, and destroy the container,
or

  lxc-start-ephemeral -o q1 -u <username> -- ps -ef > psout

which will leave the output in username's ~/psout

If you want to use lxc-init, it an lxc-execute-ephemeral shouldn't be too
hard to whip up.

-serge