Docker reserve a certain amount of memory for container

Question

I'm running npm inside a docker container and every so often it aborts because it cannot allocate enough memory. I see some flags like --memory (How do I set resources allocated to a container using docker?) for the docker run command that seem to limit the maximum amount of memory that a container can consume, but haven't seen anything yet that would allow me to reserve an amount of memory for the container and abort immediately if it cannot be allocated.

Answer 1

You can't reserve memory in docker, only limit it with --memory.

See: https://docs.docker.com/engine/reference/run/ for more detail.

Specifically look at the user memory constraints section.

memory=inf, memory-swap=inf (default) >>>> There is no memory limit for the container. The container can use as much memory as needed.

Note that's the default. So like other processes on the system npm will use all it can get/need.

So either free up some memory or add more.

Answer 2

As others have said, you cannot reserve memory for processes, and therefore containers. However, you could have the node app called from a script that will check the available memory and exit if it is below a certain threshold.