[lxc-users] Problems with user sessions inside a Ubuntu Desktop Container

[Serge Hallyn]

Quoting Alain St-Denis (alain at zenfolie.org):
> Hi,
> 
> I experience the exact same problem. Similar setup (wily host, elementary freya container). No user session is created when I login the desktop so polkit won't grant elevated privileges.
> 
> In the container, /proc/1/cgroup shows:
> 
> 10:cpu,cpuacct:/lxc/topaze
> 9:freezer:/lxc/topaze
> 8:devices:/lxc/topaze
> 7:memory:/lxc/topaze
> 6:cpuset:/lxc/topaze
> 5:net_cls,net_prio:/lxc/topaze
> 4:hugetlb:/lxc/topaze
> 3:perf_event:/lxc/topaze
> 2:blkio:/lxc/topaze
> 1:name=systemd:/lxc/topaze
> 
> In the container auth.log, I see those lines:
> 
> Jan 24 15:20:09 topaze systemd-logind[1739]: cgmanager: cgm_list_children for controller=systemd, cgroup_path=lxc/topaze/user failed: invalid request
> Jan 24 15:20:09 topaze systemd-logind[1739]: New seat seat0.
> Jan 24 15:20:09 topaze systemd-logind[1739]: Preallocating VTs...
> Jan 24 15:20:09 topaze systemd-logind[1739]: systemd-logind running as pid 1739
> Jan 24 15:20:11 topaze lightdm: pam_systemd(lightdm-greeter:session): Failed to create session: Invalid argument
> 
> The container runs cgproxy.
> 
> On the host, cgmanager reports:
> 
> jan 24 15:20:09 opale cgmanager[952]: cgmanager: Invalid path /run/cgmanager/fs/none,name=systemd//lxc/topaze/lxc/topaze/user (No such file or directory)
> jan 24 15:20:09 opale cgmanager[952]: cgmanager:list_children_main: Could not determine the requested cgroup (systemd:lxc/topaze/user)
> jan 24 15:20:09 opale cgmanager[952]: cgmanager: Error getting children for systemd:lxc/topaze/user for pid 2095
> 
> Does anybody have a hint on what causes this cgroup path duplication (lxc/topaze/lxc/topaze)? I suspect it may have something to do with the issue.

I don't know what elementary freya is, but maybe this is a bug in the systemd
package there.  Get the cgroxy logs (start it with --debug), and see what
calls are being made to it.  Better yet strace the login process (maybe
start with the getty or sshd).  If it is reading the cgroup path from
/proc/self/cgroup and then using cgmanager to movepid to something based on
that, that's wrong.