blog/content/posts/2024/reconcile-docker-with-deutsche-bahn/index.md

title	description	date	draft	toc	scrolltotop	tags
Reconcile Docker With Deutsche Bahn	If WiFi does not work on Deutsche Bahn's ICE trains and you have Docker installed, there may be network interference which can be fixed easily.	2024-09-26T09:07:30Z	false	false	true	network Deutsche Bahn Docker travel

If you happen to be a (Linux) power user travelling on a Deutsche Bahn ICE long-distance train and you wonder why you don't get a working network connection with the complemenatary "WIFIonICE" wireless network, there may be a network interference on your laptop.

There are multiple solutions for this on the web. My favorite solution is to change Docker's network configuration by editing (or creating) the file /etc/docker/daemons.json. However, you may need to prune existing Docker networks first. Otherwise the Docker service will fail to start with the following message:

failed to start daemon: Error initializing network controller: error creating default "bridge" network: all predefined address pools have been fully subnetted

Therefore, I recommend the following steps (this is on a Fedora Linux system with systemd):

1. Stop any docker containers that you may have running, including services managed by docker compose.

2. Prune the networks:

   docker network prune
   

3. Create or edit /etc/docker/daemon.json so that it contains the following:

   {
       "default-address-pools":
       [
           {"base":"172.19.0.0/16","size":24}
       ]
   }
   

4. Restart docker:

   systemctl restart docker
   

5. Connect to WIFIonICE and enjoy your network connection :-)

References

• StackExchange answer that provides the solution as presented here -- see also the answer about pruning the networks below.

  https://unix.stackexchange.com/a/539258/110635

• If you don't want to or cannot configure your Docker networks, you can also turn Docker off and on again when you travel:

  https://kuttler.eu/code/ice-wlan-linux-docker/

  This is what I used to do myself, but nowadays I prefer to just configure the Docker network differently.

• There are many more internet sources (and I have just added another one...), I won't copy all those links into my post, see DuckDuckGo search results for yourself:

  https://duckduckgo.com/?q=docker+wifi+on+ice