memory limits in docker containers

docker-limits.sh

#!/bin/bash

# Demonstrate memory resource limits in docker
# See also http://stackoverflow.com/a/20111960

function demo() {
  mem=$1
  echo "Run a container and limit to $mem"

  cid=$(docker run -d -m $mem busybox /bin/sh -c "tail -f /var/log/*")

  file=$(find /sys -regex ".*$cid.*memory.limit_in_bytes" 2> /dev/null)
  bytes=$(cat $file)
  MiB=$(( $bytes / 1024**2 ))
  printf '%-25s %s (%s Mebibytes)\n' $(basename $file) $bytes $MiB

  echo "Stop and remove $cid"
  docker stop $cid &> /dev/null
  docker rm $cid &> /dev/null
  echo
}

for mem in 1M 512M 1G; do
  demo $mem
done

output.txt

Run a container and limit to 1M
memory.limit_in_bytes     1048576 (1 Mebibytes)
Stop and remove 5976e05f443062da3fcd3fda8bedc4f9dcf83c675b6abb5473bf4e20ba1c46fd

Run a container and limit to 512M
memory.limit_in_bytes     536870912 (512 Mebibytes)
Stop and remove 733d8fd1d27518189e5730677f6bc9c901f8ae5e7940bb2bd402f6be275b849d

Run a container and limit to 1G
memory.limit_in_bytes     1073741824 (1024 Mebibytes)
Stop and remove 036f2f01a5c9db4f30fcb6354c7c5a4125787c72b5cf49088b4ce2cf6405bb85