Solution for How to increase maximum Docker Network

General
1

When You achieve limit of 30 created docker networks, You cannot add new app (which require their own network). casaOS during install app display error: “docker: all predefined address pools have been fully subnetted“

You can manually clear some unused:

# list all
docker network ls

# remove net. <NETWORK_ID> or <NAME>)
docker network rm <NETWORK_ID>

# remove all unused
docker network prune -f

I do not understand, why this limit was made so small. But solution is simply:

Create (or edit) on Host: /etc/docker/daemon.json

{
   "default-address-pools": [
        {
            "base":"172.17.0.0/12",
            "size":16
        },
        {
            "base":"192.168.0.0/16",
            "size":20
        },
        {
            "base":"10.99.0.0/16",
            "size":24
        }
    ]
}

First two are default docker address pools, last is one of the private network.

Restart service docker:

sudo systemctl restart docker

Wait a while. And see webUI, 80 % of apps works, some are gray. You need to click on them for reload.

There is handy one-liner for list all containers and their networks- network size and container itself IP inside container:

sudo docker ps -aq | while read cid; do
  cname=$(docker inspect --format='{{.Name}}' "$cid" | sed 's#^/##')
  docker inspect --format='{{range $net,$cfg := .NetworkSettings.Networks}}{{$net}} {{$cfg.IPAddress}}\n{{end}}' "$cid" |
  while read net ip; do
    subnet=$(docker network inspect "$net" \
      --format='{{if .IPAM}}{{(index .IPAM.Config 0).Subnet}}{{else}}-{{end}}')
    printf "\e[1;34m%-40s\e[0m  %-15s  %-30s  \e[1;32m%s\e[0m\n" \
      "$cname" "$net" "$subnet" "$ip"
  done
done

Tested for docker version 28.5.2, which is apt-hold for upgrade, until fix this issue.