Docker: How to limit memory usage

By starting your container you can limit the RAM usage simply by adding

-m 4M

(this limits the memory to 4 megabytes).

To check this simply run:

docker run -it -m=4M  --rm alpine /bin/ash

and on your docker machine check the following entry:

alpine:~# cat /sys/fs/cgroup/memory/docker/4ce0403caf667e7a6d446eac3820373aefafe4e73463357f680d7b38a392ba62/memory.limit_in_bytes 
4194304