[systemd-devel] How can I map PID between host and container?

[WaLyong Cho]

Hello,

I'm looking for a proper way what method to map PID between host and
container.

In case of systemctl, if I know pid in container(let's call this pid_c)
then I can find the pid in sight of host(let's call this pid_h) by using
"systemctl -M {container} pid_c" in host shell. But I can not find pid_c
when I know pid_h by using "systemctl status pid_h".

The former seems possible by parsing machine cgroup.
In the latter case, can we also find the pid_c?

And is there any other method to map between those?
For example, when if I use lxc then how I find each pid? (lxc-ps?)
According to my search, namespace can give me some of hints about this.
I could not find more detail.
Is there any proper libs or tools for this?


Thanks,
WaLyong