How to change configuration of existing docker network - docker

Question

I have an existing (MacVLAN) docker network called "VPN" to which I normally attach docker containers that I all want to run on a VPN. There are two single 'host' docker containers running openvpn, each with their own IP, and I attach other containers to these as I please.
I have recently moved, and my new router is at address 192.168.0.1. However, the old house's router had the gateway at 192.168.2.254, and the existing docker network had the subnet mask, the IP range and the gateway all configured for this.
If I run docker network inspect VPN it gives:
[
{
"Name": "VPN",
"Id": [anidea],
"Created": [sometimenottolongago],
"Scope": "local",
"Driver": "macvlan",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": {},
"Config": [
{
"Subnet": "192.168.2.0/24",
"IPRange": "192.168.2.128/28",
"Gateway": "192.168.2.254"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {},
"Options": {
"parent": "enp5s0"
},
"Labels": {}
}
]
There were two machines on the network, and I cannot access them currently. Both machines are a container to which other containers are attached to.
I have tried:
Recreating the docker containers with new IP addresses on the subnet of the new home network. This doesn't work as the docker network "VPN" allows only IP's on the old range.
Access the docker containers/machines at their old IP. Then I get a timeout; possibly I need to design some IP routing or something? This is where my knowledge (if any) starts getting cloudy.
I think the best is to just update the docker network "VPN" to play nice with the new Gateway/router/home network; I would like to change the IPAM["Config"] parameters to update for the new gateway and subnet. However, I can't find online how to do this (the only things that come up is how to change the default settings for the default docker network).
Long story short:
How do I change configuration/parameters of an existing docker network?
If, in the end, this is a bad way of doing things (for instance, if I can access the containers on the network as-currently-is), I'm also open for ideas.
The host machine is running ubuntu-server 20.04.1 LTS.
Thanks in advance.

Answer 1

The simplest approach to this would be to delete the VPN network and create it anew with new parameters but the same name. If you use docker-compose up to recreate containers, include the networks section in the first container that you recreate.
First, run this to delete the existing network:
docker network rm VPN
Then add the macvlan network definition to yml of your first re-created container. Here is the networks section I used, adapted somewhat to your situation:
networks:
VPN:
driver: macvlan
enable_ipv6: true # if needed
driver_opts:
parent: eth0
ipam:
config:
- subnet: 192.168.0.0/24
gateway: 192.168.0.1
ip_range: 192.168.0.8/30 # reserve some IP addresses for other machines
# in that subnet - adjust as needed
- subnet: xx:xx:xx:xx::/63 # put your IPv6 subnet here if needed
gateway: xx:xx:xx:xx:xx::xx # IPv6 (external) of your router
Alternatively, you could change your new router config to match the old one, and leave your macvlan VPN as is.