How to set the CPU priority (niceness) of a Docker container?

Question

One of my containers is always busy, and is taking CPU away from other containers (webservers) that need to be responsive and are only active from time to time.

I would like to lower the CPU priority of the CPU-consuming container, so that whenever the other containers need the CPU, it is not clogged.

How do I do this? I have been searching the web for a while now, but I can't find the answer.

I have tried running the container with --entrypoint='nice 10 mybinary', but it turns out --entrypoint can only run binaries, not shell commands.

Answer 1

You can limit CPU resources on the container level. I recommend to use --cpu-shares 512 for your case.

https://docs.docker.com/config/containers/resource_constraints/:

Set this flag to a value greater or less than the default of 1024 to increase or reduce the container’s weight, and give it access to a greater or lesser proportion of the host machine’s CPU cycles. This is only enforced when CPU cycles are constrained. When plenty of CPU cycles are available, all containers use as much CPU as they need. In that way, this is a soft limit. --cpu-shares does not prevent containers from being scheduled in swarm mode. It prioritizes container CPU resources for the available CPU cycles. It does not guarantee or reserve any specific CPU access.