Custom assembly issues

Hello all,

I'm trying to create a custom server assembly. I've started by trying to
recreate the distributed app from here:
james-project/CassandraRabbitMQJamesServerMain.java
at master · apache/james-project (github.com)
<https://github.com/apache/james-project/blob/master/server/apps/distributed-app/src/main/java/org/apache/james/CassandraRabbitMQJamesServerMain.java>

This compiles  okay but I get an error about a bad request to ElasticSearch
when trying to start up the metrics.

I can get rid of this by removing the ElasticSearchMetricReporterModule
from the build but then the server just hangs while loading its config. The
final line in the logs is:

21:35:48.208 [INFO ] o.a.j.CONFIGURATION - Load configuration file
/root/conf/webadmin.properties

Otherwise there's no clues as to what it's doing. I'm running it under
docker-compose using the compose file from the server/apps/distributed-app
directory. There are a couple of errors about connecting to Cassandra but
these are just while the server boots - once Cassandra starts it seems okay.

Is there a way to increase the logging or some other way to find out
what's happening?

Thanks in advance,

Felix