the default for rest_transport_uri leads to non deterministic behavior

+1 to this.

The standard FCB bundle now has graylog-mongodb deployed in an lxd container on the graylog unit. This didn't used to be the case, which is why this bug has only recently surfaced.

We worked around this by changing the juju config for rest_transport_uri to the "real" primary IP of the graylog unit:

  juju config graylog rest_transport_uri=http://10.1.2.3:9001/api/

Another work-around would be to not put graylog-mongodb in a lxd container on the graylog unit.

Perhaps something like this, which we use in various other places, to work out the primary / default IP address used by the unit to communicate with the world:

| def get_ip_address():
| # http://stackoverflow.com/questions/166506/finding-local-ip-addresses-using-pythons-stdlib
| import socket
| s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
| # No connection is actually made to this address, so there are no firewalling requirements.
| s.connect(('91.189.89.199', 123))
| ip = s.getsockname()[0]
| s.close()
| return netaddr.IPAddress(ip)