Using `astro-dnssd`-based code within (Linux) containers

[DazWilkin]

Thanks for providing a x-plat ZeroConf crate.

I had challenges getting the Example to work in a Linux container.

IIUC, the crate requires libavahi-compat-libdnssd-dev and dbus and avahi-daemon services.

When containerizing, I used:

ENTRYPOINT ["bash", "-c", "service dbus start && service avahi-daemon start && ./server"]

I think this (more commonly putting the commands in a script file) is the preferred way to start daemons needed for an executable

But I was unable to browse the service from the host as expected.

If I ran the commands manually (outside) of a subshell, it worked.

By adding a small delay between starting the daemons and running the server, the problem appears solved, i.e.:

ENTRYPOINT ["bash", "-c", "service dbus start && service avahi-daemon start && delay 2s && ./server"]

I'm reporting this here in the hopes that it helps someone else avoid -- what was for me -- an unexpected issue (and solution)

See: https://stackoverflow.com/questions/65043317/challenged-accessing-containerized-dns-sd/