Could not register this Router instance with the cluster because querying this host's hostname from OS failed

In some circumstances it may be necessary to add the --report-host option to the bootstrap command.

In a fairly simple environment deployed on OpenStack with no spaces, a normal looking /etc/hosts and forward and reverse DNS working as expected we saw the following error:

Error: Could not register this Router instance with the cluster because querying this host's hostname from OS failed:
  Could not get local host address: Temporary failure in name resolution(errno: -3)
You may want to try --report-host option to manually supply this hostname.

Full unit log: https://pastebin.canonical.com/p/7wfZb22qmr/