Re: Container Uptime Discussion

On 2/8/24 2:56 PM, Craig Small (csmall) wrote:
> 
> So, let me get this straight.
> Get both PID1 elapsed and uptime.
> If PID1 has a shorter elapsed time, then use that's its docker and 
> friends.  e.g. /proc/uptime is 100 seconds, PID1 etimes is 2 seconds = 
> uptime is 2 seconds
> If PID1 has a longer elapsed time, then use that as its lxc. e.g. 
> /proc/uptime is 1 second, PID1 etimes is 2 seconds = uptime is 1 second.

Hi Craig,

First call the regular procps_uptime.  That double will be either the 
host (bigger) or an adjusted container (smaller) running time.

Then get both PIDS_TIME_START and PIDS_TIME_ELAPSED for PID1.

If PIDS_TIME_START is greater than the uptime seconds it indicates an 
lxc container and /proc/uptime can be used.

Otherwise, the existing path is taken.

But watch out for a complication presumably on a host.  The new call to 
procps_uptime might fail if /proc was mounted subset=pid.  In that case 
the existing path should be taken.

Regards,

Jim