Include mdns packages: nss-mdns and avahi in base fedora-IoT

[say-paul]

Please try to answer the following questions about the package you are requesting:

1. Is the package installed by default in a Fedora Edition? If yes, which one.
   yes , Fedora Workstation.

2. What, if any, are the additional dependencies on the package? What is the output of this command on a system without overrides or locally installed packages:

rpm-ostree install --dry-run avahi
Checking out tree 1e53e84... done
Enabled rpm-md repositories: fedora-cisco-openh264 updates fedora
Updating metadata for 'fedora-cisco-openh264'... done
Updating metadata for 'updates'... done
Updating metadata for 'fedora'... done
Importing rpm-md... done
rpm-md repo 'fedora-cisco-openh264'; generated: 2024-03-11T19:22:31Z solvables: 3
rpm-md repo 'updates'; generated: 2025-06-12T02:23:59Z solvables: 25723
rpm-md repo 'fedora'; generated: 2024-10-24T13:55:58Z solvables: 67029
Resolving dependencies... done
Installing 3 packages:
  avahi-0.8-29.fc41.aarch64 (fedora)
  avahi-libs-0.8-29.fc41.aarch64 (fedora)
  libdaemon-0.14-30.fc41.aarch64 (fedora)
Exiting because of '--dry-run' option

rpm-ostree install --dry-run nss-mdns
Checking out tree 1e53e84... done
Enabled rpm-md repositories: fedora-cisco-openh264 updates fedora
Importing rpm-md... done
rpm-md repo 'fedora-cisco-openh264' (cached); generated: 2024-03-11T19:22:31Z solvables: 3
rpm-md repo 'updates' (cached); generated: 2025-06-12T02:23:59Z solvables: 25723
rpm-md repo 'fedora' (cached); generated: 2024-10-24T13:55:58Z solvables: 67029
Resolving dependencies... done
Installing 4 packages:
  avahi-0.8-29.fc41.aarch64 (fedora)
  avahi-libs-0.8-29.fc41.aarch64 (fedora)
  libdaemon-0.14-30.fc41.aarch64 (fedora)
  nss-mdns-0.15.1-12.fc41.aarch64 (fedora)
Exiting because of '--dry-run' option

3. What is the size of the package and its dependencies?

λ rpm -qi  nss-mdns | grep Size
Size        : 160711

λ rpm -qi  avahi | grep Size
Size        : 1646305

4. What problem are you trying to solve with this package? Or what functionality does the package provide?
   When installing Fedora IoT on an RPi and getting it connected to the network, I need to find the IP address that the DHCP server assigned in the network router, which I may not always have access to. So I need the device to be accessible through the preconfigured .local

5. Can the software provided by the package be run from a container? Explain why or why not.
   Can be run in a container.

6. Can the tool(s) provided by the package be helpful in debugging container runtime issues?
   No.

7. Can the tool(s) provided by the package be helpful in debugging networking issues?
   Yes

8. Is it possible to layer the package locally via rpm-ostree install <package>? Explain why or why not.
   Yes

[nullr0ute]

What is the size of the package and its dependencies?

The reports you include don't include the dep size. Overall it's about 2.5Mb

I have a number of concerns here:

1. mdns works in a lot of cases when the router/dhcp advertises the device names via lease. This is how it works on my home network with Fedora IoT instances so in most home network cases it will work without this.
2. A lot of networks, corporate/industrial/etc actually block mdns so it may cause problems. This is why it was never included by default

There's also two things conflated here and I'm not 100% sure what you're trying to achieve in the two dependencies so I'd like some more information for the two packages:

1. nss-mdns is a plugin to the NSS service to provide mdns lookup within apps running on Fedora. This is also generally provided now by system-resolved so I'm don't believe this actually provides any benefit here. Please explain more why we would need this by default.

2. avahi is primarily used to advertise services running on a system, eg it's used by cups to advertise a shared printer, so again I'm not sure exactly what we're getting by installing it by default. The hostname should resolve just fine with mdns without avahi running on networks where it's not blocked.

WRT to Workstation, nss-mdns is a dependency of cef/chromium (and kdnssd on KDE) so it's installed so that works as expected. avahi is there for printer sharing out of the box. I don't think we need those by default on IoT.

[Ciantic]

I think it's totally fine to not support mDNS by default, and I can't know what the original poster was after, but I came here because I want to enable mDNS, e.g. so that in a local network my Fedora IoT device is reachable via pi.local which is the default way Raspberry Pi Os is reachable.

This might be reason others are appearing here as well from Google Search.

Here is the solution

Create Dockerfile that serves only the mDNS via Avahi:

(This hardcodes pi.local as your hostname, change when necessary)

FROM alpine:latest

RUN apk add --no-cache avahi

RUN sed -i 's/^#enable-dbus=yes/enable-dbus=no/' /etc/avahi/avahi-daemon.conf && \
    sed -i 's/^#host-name=.*/host-name=pi/' /etc/avahi/avahi-daemon.conf && \
    sed -i 's/^#domain-name=.*/domain-name=local/' /etc/avahi/avahi-daemon.conf

CMD ["avahi-daemon", "--no-chroot", "--debug", "--no-drop-root"]

Then execute it:

#!/bin/bash
podman build . -t custom-mdns
podman run --rm -it --net=host --name custom-mdns custom-mdns

I hope it helps somebody else too.