determine if nbresuse is running in docker or pod #66
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Get resources and usages in docker, and return the correct values i think
Determine if nbresuse running in docker
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forgot import os module |
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Thanks @xianglei. It's true the limits are for now not accurate when running in a container (not taking the cgroups limits into account). |
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| @staticmethod | ||
| def __if_dockerized(): | ||
| if os.path.exists('/.dockerenv'): |
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Is this a reliable way of detecting whether it is running in Docker? Does this file exist with other container engines?
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It's not present on Podman.
I found this stackoverflow question which provides a bit of background: https://superuser.com/questions/1021834/what-are-dockerenv-and-dockerinit
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I just checked with Kubernetes K3S too, it's also not present.
However it looks like /sys/fs/cgroup/memory/memory.limit_in_bytes is set to <very large number> if there's no limit:
k3os-5708 [~]$ kubectl run tmp-shell --rm -i --tty --image busybox -- /bin/sh
If you don't see a command prompt, try pressing enter.
/ # cat /.dockerenv
cat: can't open '/.dockerenv': No such file or directory
/ # cat /sys/fs/cgroup/memory/memory.limit_in_bytes
9223372036854771712
k3os-5708 [~]$ kubectl run tmp-shell --rm -i --tty --image busybox --limits=memory=10Mi -- /bin/sh
If you don't see a command prompt, try pressing enter.
/ # cat /sys/fs/cgroup/memory/memory.limit_in_bytes
10485760
So one solution might be to see if /sys/fs/cgroup/memory/memory.limit_in_bytes exists, and if so use min(/sys/fs/cgroup/memory/memory.limit_in_bytes, total-system-memory), and skip the container check completely?
It's also worth noting that cgroups2 is different, I haven't figured out how to find the memory limit there.
Returns the correct memory & cpu values when nbresuse running in a docker or pod environment