The Problem

Linux doesn't have a dedicated Docker application like Windows and OSX that allows you to easily place resource constraints on the docker daemon. So if you spin up a bunch of resource hungry containers, it'll slow your computer to a crawl and/or start a fire.

Observe the Problem

Uses the image from https://hub.docker.com/r/polinux/stress to see the issue in practice. Run these beforehand to see just how much CPU/RAM docker can take up, and then run them making the adjustments below to see how the docker containers get limited.

You'll want to install ctop and have it running to be able to monitor the container usage:

sudo wget https://github.com/bcicen/ctop/releases/download/v0.7.3/ctop-0.7.3-linux-amd64 -O /usr/local/bin/ctop
sudo chmod +x /usr/local/bin/ctop

Run a single CPU stress

docker run -it --rm polinux/stress stress --cpu 1 -t 30

Run a single RAM stress

docker run -it --rm polinux/stress stress --vm-bytes 1G --vm-keep -m 1

Run multiple CPU stress containers

docker run -d --rm --name stress_1 polinux/stress stress --cpu 1 -t 30 && \
docker run -d --rm --name stress_2 polinux/stress stress --cpu 1 -t 30 && \
docker run -d --rm --name stress_3 polinux/stress stress --cpu 1 -t 30 && \
docker run -d --rm --name stress_4 polinux/stress stress --cpu 1 -t 30

Run multiple RAM stress containers

docker run -d --rm --name stress_1 polinux/stress stress --vm-bytes 4G --vm-keep -m 1 -t 30 && \
docker run -d --rm --name stress_2 polinux/stress stress --vm-bytes 4G --vm-keep -m 1 -t 30 && \
docker run -d --rm --name stress_3 polinux/stress stress --vm-bytes 4G --vm-keep -m 1 -t 30

Fix the Problem

If you want to know how/why this works, see the References section below

Create config files for docker daemon

Edit /etc/docker/daemon.json with this content:

{
  "cgroup-parent": "/docker_limit.slice"
}

Edit /etc/systemd/system/docker_limit.slice with this content:

Description=Slice that limits docker resources
Before=slices.target

[Slice]
# CPU Management
CPUAccounting=true
CPUQuota=333%

# Memory Management
MemoryAccounting=true
MemoryHigh=4G
MemoryMax=6G

Enable and start docker slice

sudo systemctl daemon-reload && sudo systemctl enable docker_limit.slice && sudo systemctl start docker_limit.slice
# sudo systemctl restart docker # not necessary

Restart related services

sudo systemctl daemon-reload && sudo systemctl restart docker_limit.slice
# sudo systemctl restart docker # not necessary

Known Issue

I haven't figured out how to make this fix stick after a reboot yet. Probably a simple fix, i just haven't looked into it hard yet. In the meantime, running the command in Restart related services

---

References

Details on resource control unit settings: https://www.freedesktop.org/software/systemd/man/systemd.resource-control.html

Details on the Docker configuration file: https://docs.docker.com/engine/reference/commandline/dockerd/#daemon-configuration-file

Original stackexchange answer that inspired this: https://unix.stackexchange.com/a/550954

Related issue on docker repo: moby/moby#29278