Comment 23 for bug 430224

You can only have one init daemon on a system, so having a separate Upstart per-chroot doesn't work - the prime system's init daemon would get the SIGCHLDs, etc. (unless you use pid namespaces and a kernel patch that Lennart once wrote to redirect init behaviour to other pids)

For me, the right solution would be that the init daemon could be made aware of chroots, e.g. through a config file. It'd then read the /etc/init directory inside the chroot, and manage those jobs along-side those in the real system - just automatically chrooting before processing the job.

The only thing missing there is some way to determine *which* job you mean; since it wouldn't be obvious to Upstart which chroot the "initctl" command was being run from