Avahi - daemon already running

[gorbunovav]

My container logs are spammed with the following message:

Daemon already running on PID X

The PID inside the container corresponds to the avahi daemon.
It has started after the upgrade from 0.9.2 version of the image (most likely after #28).

I am running the container with "network_mode: host" on Raspberry PI, which already has the avahi daemon running on the host.

Environment:

Raspberry Pi 4
Raspbian 10
Docker version 19.03.5, build 633a0ea
Image: mozillaiot/gateway:0.10.0-arm

docker-compose.yml:

version: "3"

services:
  webthings-gateway:
    container_name: webthings-gateway
    image: mozillaiot/gateway:arm
    restart: unless-stopped
    network_mode: host
    ports:
      - "8080:8080"
      - "4443:4443"
    volumes:
      - ./data:/home/node/.mozilla-iot

[mrstegeman]

I knew this was going to cause some issues...

Would an environment variable help? That way, you could disable avahi selectively.

[mrstegeman]

@white-gecko do you have a better solution for this?

[gorbunovav]

@mrstegeman as far as I understand the avahi daemon is required for the webthing-arduino add-on only, right?

In that case, I am ok with the environment variable solution, since I am not going to use it in the nearest feature 🤔

[mrstegeman]

It's used for a couple things:

• Publishing the hostname to the network, so that from a browser, you can navigate to http://gateway.local
• Doing .local DNS lookups, which are primarily (but not only) used by native web things (e.g. using the webthing-* libraries).

Neither of these are absolutely necessary, but are definitely conveniences.

[white-gecko]

Ah yes, I can see the same message in my logs as well. But I think the avahi daemons seam not to further interfere as it seems to me.

[white-gecko]

But sure I think an environment variable could control whether the daemon should be running. But this would not solve the issue to prevent the log messages.

[mrstegeman]

I think the issue here is that avahi is running on the host as well, and the Docker container is using host networking, so the two are somehow interfering.

[snorp]

I have this log message too, and my host (CoreOS) isn't running avahi.