Docker Gateway image and mDNS

WebThings
,
1

When my Gateway was installed as a deb package on my raspberry Pi 4, it recognised my own built webthing by domain name. This name is not in my pi4’s /etc/hosts file, so, as I do not run a DNS server on my LAN, it must have got the name via mDNS.

Now I moved the Gateway to a docker image using the host network (on a stock docker image) & some config/db.sqlite3 voodoo to connect to my existing account. I can access my own built webthings by IP, but not by domain name any longer.

So it seems that mDNS is broken in the docker image.

2

Is your Docker container using host networking? That is required for mDNS to work.

If you’re interested, we had a long discussion about mDNS inside the image about a year ago: https://github.com/WebThingsIO/gateway-docker/issues/24

3

Yes, I use host networking:

docker run \
      -d \
      -e TZ=<my TZ> \
      -v /home/pi/docker-local-files/webthings-gateway:/home/node/.webthings \
      --network="host" \
      --log-opt max-size=1m \
      --log-opt max-file=10 \
      --name webthings-gateway \
      webthingsio/gateway:latest

Indeed an interesting discussion. If I understand correctly, all issues were resolved.

4

Hi - so what was the outcome of this - I cannot reach my MDNS hosts from inside the container. The gateway name gateway cannot be seen from the linux host using ahi-browse -a -t --resolve | grep gateway.

I saw in some discourse that dbus need to be off in a config file - couldnt figure our which file - there is an avahi conf file - has the domain config commented out.

Can someone assist?

5

Sorry, but I still have not figured it out.