Check mem_limit within a docker container
Previously the /sys/fs/cgroup/memory/memory.limit_in_bytes
worked for me, but in my ubuntu with kernel 5.8.0-53-generic
seems that the correct endpoint now is /sys/fs/cgroup/memory.max
to recover the memory limit from inside the container.
On the host you can run docker stats
to get a top
like monitor of your running containers. The output looks like:
$ docker stats
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
729e4e0db0a9 dev 0.30% 2.876GiB / 3.855GiB 74.63% 25.3MB / 4.23MB 287kB / 16.4kB 77
This is how I discovered that docker run --memory 4096m richardbronosky/node_build_box npm run install
was not getting 4G of memory because Docker was configured to limit to 2G of memory. (In the example above this has been corrected.) Without that insite I was totally lost as to why my process was ending with simply "killed
".
Worked for me in the container, thanks for the ideas Sebastian
#!/bin/sh
function memory_limit
{
awk -F: '/^[0-9]+:memory:/ {
filepath="/sys/fs/cgroup/memory"$3"/memory.limit_in_bytes";
getline line < filepath;
print line
}' /proc/self/cgroup
}
if [[ $(memory_limit) < 419430400 ]]; then
echo "Memory limit was set too small. Minimum 400m."
exit 1
fi
The memory limit is enforced via cgroups. Therefore you need to use cgget
to find out the memory limit of the given cgroup.
To test this you can run a container with a memory limit:
docker run --memory 512m --rm -it ubuntu bash
Run this within your container:
apt-get update
apt-get install cgroup-bin
cgget -n --values-only --variable memory.limit_in_bytes /
# will report 536870912
Docker 1.13 mounts the container's cgroup to /sys/fs/cgroup
(this could change in future versions). You can check the limit using:
cat /sys/fs/cgroup/memory/memory.limit_in_bytes