`ps` of specific container from host-CodePudding

in the host, is there any way to get ps of specific container?

if a container having cgroup foo has processes bar, baz, bam then like ps --cgroup-id foo should print the result of ps as if in the container(cgroup) as follows:

PID   USER     TIME  COMMAND
    1 root      0:00 bar
   60 root      0:00 baz
  206 root      0:00 bam

it doesn't have to be ps though, I hope it could be made of just one or two commands.

Thanks!

CodePudding user response：

There's a docker top command, e.g.:

$ docker top 9f2
UID                 PID                 PPID                C                   STIME               TTY                 TIME                CMD                                                                   
root                20659               20621               0                   Oct08               ?                   00:00:00            nginx: master process nginx -g daemon off;                            
systemd             20825               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20826               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20827               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20828               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20829               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20830               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20831               20659               0                   Oct08               ?                   00:00:00            nginx: worker process                                                 
systemd             20832               20659               0                   Oct08               ?                   00:00:00            nginx: worker process

Or you can exec into the container if the container ships with ps:

docker exec $container_name ps

And if ps isn't included in the container, you can run a different container in the same pid namespace:

$ docker run --pid container:9f2 busybox ps -ef
PID   USER     TIME  COMMAND
    1 root      0:00 nginx: master process nginx -g daemon off;
   23 101       0:00 nginx: worker process
   24 101       0:00 nginx: worker process
   25 101       0:00 nginx: worker process
   26 101       0:00 nginx: worker process
   27 101       0:00 nginx: worker process
   28 101       0:00 nginx: worker process
   29 101       0:00 nginx: worker process
   30 101       0:00 nginx: worker process
   31 root      0:00 ps -ef