This was never consistently showing the host key and sshfp records
upon launch.
Upon digging, a number of things are going wrong.
The socket.create_connection() check isn't waiting for the host to be
up properly. This means the keyscans were not working, and we'd get
blank return values [1]. We have a ssh_connect() routine, rework it
to use that to probe. We add a close method to the sshclient so we
can shut it down too.
I don't know why the inventory output was in dns.py, as it's not
really DNS. Move it to the main launch_node.py, and simplify it by
using f-strings. While we're here, deliminate the output a bit more
and make white-space more consistent.
This allows us to simplify dns.py and make it so it handles multiple
domains.
Since we're actually waiting for ssh to be up now, the keyscan works
better and this outputs the information we want. A sample of this is
https://paste.opendev.org/show/b1MjiTvYr4E03GTeP56w/
[1] ssh-keyscan has a very short timeout, and just returns blank if it
doesn't get a response to it's probes. We weren't checking its
return code.
Change-Id: I06995027a4b80133bdac91c263d7a92fd495493b
03de935048