Different CRUN/RUNC cgroup hierarchy about crun HOT 6 CLOSED

I think the issue is that you are setting a systemd cgroup in the OCI configuration file but didn't use --systemd-cgroup to the OCI runtime.

Could you run $OCI_RUNTIME --systemd-cgroup run -d -b .... and compare them again?

from crun.

Basically you are correct that with --systemd-cgroup crun/runc hierarchies identical:

-.slice
└─system.slice (#43)
  ├─runc-fcfcc473-64a0-41bc-bb61-8ca3801c7e0f.scope … (#3141)
  │ → trusted.delegate: 1
  │ → trusted.invocation_id: 96501da102af47ffae740d837a05726f
  │ └─ 2727 python3 -u main.py

-.slice
└─system.slice (#43)
  ├─crun-fcfcc473-64a0-41bc-bb61-8ca3801c7e0f.scope … (#2676)
  │ → trusted.delegate: 1
  │ → trusted.invocation_id: 8d2b9a3448774046bca968cca71c4d50
  │ └─container (#2716)
  │   └─ 2710 python3 -u main.py

Nevertheless I haven't found systemd cgroup in the OCI configuration file.

I think there is a difference in behavior between crun & runc for cases without --systemd-cgroup option. I suppose crun creates child cgroup inherited from the root, while runc from the parent cgroup. Example for crun/runc under systemd:

=>> crun

Control group /:
-.slice
├─fcfcc473-64a0-41bc-bb61-8ca3801c7e0f (#1812)
│ └─ 852 python3 -u main.py

=>> runc

Control group /:
-.slice
└─system.slice (#43)
  ├─system-aos\x2dservice.slice (#1754)
  │ → trusted.invocation_id: fbd62be6c5534072bc6193702d1bdb25
  │ ├─fcfcc473-64a0-41bc-bb61-8ca3801c7e0f (#2186)
  │ │ └─ 859 python3 -u main.py
  │ └─[email protected] (#1783)
  │   → trusted.invocation_id: a94e0068c56e44b4ba481b7a709a797a

=>> cgroup of systemd service

root@node0:~# systemctl status [email protected]
● [email protected] - AOS Service
    Process: 852 ExecStart=/usr/bin/runc run -d --pid-file /run/aos/runtime/fcfcc473-64a0-41bc-bb61-8ca3801c7e0f/.pid -b /run/aos/runtime/fcfcc473-64a0-41bc-bb61-8ca3801c7e0f fcfcc473-64a0-41bc-bb61-8ca3801c7e0f (code=exited, status=0/SUCCESS)
     CGroup: /system.slice/system-aos\x2dservice.slice/[email protected]
             ‣  859 python3 -u main.py

Attaching container configuration:
cat-config.json

I can also share strace output for both cases if required.

from crun.

if you don't specify the --systemd-cgroup option, then you must specify the cgroup path as it is on the cgroup file system (e.g. foo/bar will become /sys/fs/cgroup/foo/bar).

from crun.

And in case when both parameters not specified then behavior is implementation defined. ie it's ok that crun/runc create different hierarchies, right?

from crun.

yes, it is implementation specific (although I remember we end up doing a similar thing)

from crun.

good to know, that's what I needed to clarify, thank you. Closing the issue.

from crun.