plugins/linux/virtualization: if lxc and docker are on the same host, it can't detect lxc

[goacid]

Description

Phys Host : ubuntu 16.04 LTS with docker engine 1.11 and lxc 2.0.1 installed.
LXC containers are ubuntu 14.04 with chef (from 11 to latest),which embeded ohai, always the same problem virtualization.rb doesn't detect the container has a guest.
With native ohai same problem.
On same environment, without docker installed in the host, it works fine.

Ohai Version

From 7.0.4 to latest (maybe before)

Platform Version

Host : Ubuntu 16.04
Lxc container : Ubuntu 14.04

Ohai Output

An LXC guest return :

"virtualization": {
    "systems": {

    }

On an LXC container running on a physical host without docker :

  "virtualization": {
    "system": "lxc",
    "role": "guest"
  },

Content of cgroup inside the ubuntu 14.04 containers :

cat /proc/1/cgroup 
9:cpu,cpuacct:/
8:pids:/
7:devices:/
6:cpuset:/
5:blkio:/
4:net_cls,net_prio:/
3:freezer:/
2:memory:/
1:name=systemd:/
root@crawler01:~# cat /proc/self/cgroup 
9:cpu,cpuacct:/
8:pids:/
7:devices:/
6:cpuset:/
5:blkio:/
4:net_cls,net_prio:/
3:freezer:/
2:memory:/
1:name=systemd:/

The problem seems here :
file virtualization.rb line 180

if File.read("/proc/self/cgroup") =~ %r{^\d+:[^:]+:/(lxc|docker)/.+$}

I'm currently searching a way to find any difference to be able to know if a container is lxc or docker from inside the container.

[huckley]

cat /proc/1/environ say what?

[goacid]

container=lxccontainer_ttys=/dev/pts/0 /dev/pts/1 /dev/pts/2 /dev/pts/3

Yes !
Next step : patching the file

[lehn-etracker]

See my patch here master...lehn-etracker:lxc-2.0
I will send a pull request after signing Chef CLA!

[goacid]

Thanks !

[jeunito]

This was an issue for me too. I have made another PR with tests passing at #1055

[tas50]

This should be fixed on master now with the updated PR from @jeunito