[Maas-devel] Packaging changes for cluster worker

[Julian Edwards]

Andres,

As discussed briefly on irc, the cluster worker (celeryd) now needs to bind 
sockets to UDP port 68 so it can receive replies to its probes for DHCP 
servers.

It uses SO_REUSEADDR so it won't clash with existing DHCP clients also bound 
to that port.

In the development environment, we use "authbind" to configure the celeryd for 
access to the port.  "man authbind" shows many ways of doing it depending on 
requirements but the dev environment HACKING.txt asks you to do:

    $ sudo touch /etc/authbind/byport/68
    $ sudo chmod a+x /etc/authbind/byport/68

But you can be more restrictive if you use the /etc/authbind/byuid/<uid> 
method.

Since the start-cluster-worker script forks off another script, we use 
"authbind --deep" to make sure the permission carries through to the forked 
process.

J