Docker started using 192.168.0.0/16 subnets all of in sudden

2021-02-03

I was having fun with Jupyter and wanted to move it to my Docker host so it can benefit from the GPU. With effective configs:

services:
  jupyterhub:
    build:
      context: /home/XXXX/dockers/labs
    command:
    - jupyter lab
    dns:
    - $GATEWAY_IP
    environment:
      NVIDIA_VISIBLE_DEVICES: all
    labels:
      traefik.http.routers.jupyter-web.rule: Host(`labs.XXX.internal`)
      traefik.http.routers.jupyter-webs.rule: Host(`labs.XXX.internal`)
      traefik.http.routers.jupyter-webs.tls: "true"
      traefik.http.routers.jupyter-webs.tls.certresolver: step-ca
    runtime: nvidia
    volumes:
    - /home/XXXX/dockers/labs/notebooks:/tf/notebooks:rw
version: '3.7'

docker-compose build erred during pip install, it took a moment to figure out it was a network issue, after checking with iptables -t nat -S I found that the snat entry for 172.16.0.0/12 is already there, to my knowledge that’s the only subnet range docker would use. Of course not!

Google sensei told me that the authors from moby chose exactly these subnets:

[ "172.17.0.0/16", "172.18.0.0/16", "172.19.0.0/16",
"172.20.0.0/14", "172.24.0.0/14" "172.28.0.0/14", "192.168.0.0/16" ]

Note that 192.168.0.0/16 is also used here.