c.DockerSpawner.extra_host_config passes only network_mode to docker

Hi all, I’m using DockerSpawner in a Docker Swarm setup. I was able to set the docker overlay network but I can not set the memory limit for the notebook containers.

# Additional args to create_host_config for container create
c.DockerSpawner.extra_host_config = {
    'mem_limit': '300m',
    'memswap_limit': '0b',
    'network_mode': 'nw-docker',
    'oom_kill_disable': False
}

This is the sample from my jupyterhub_config.py file. Only the network_mode setting is recognized by docker. I checked this by running docker inspect on a running notebook container.

How can we fix this?

Thanks

[willingc]

Super @matteoipri! Thanks for the detailed response 🍰

I’m going to label this a ‘reference’ since it will likely help someone else too.

[ZelphirKaltstahl]

To me it is not clear, if the line in /etc/default/grub has to be added for DockerSpawner to pick up the config parameters about memory and swap memory. Can someone please clarify which of the steps @matteoipri described are necessary in which setup (DockerSpawner and normal Spawner used by JupyterHub)?

At the moment I see the opposite, with a configuration of:

c.DockerSpawner.extra_host_config = {
    'network_mode': network_name,
    'cpuset_cpus': '0-3',
    'mem_limit': '1024m',
    'memswap_limit': '2048m'
}

DockerSpawner does not set a swap limit. It does not appear in docker inspect container-name. Instead I see -1 there for memory swap limit.

Also: Does the cgroup memory usually already exist on a Ubuntu machine? Or was it created and configured elsewhere, before running the containers the way described?