Diagnose why Tomcat doesn't appear to deploy webapp module

I'm trying to set up an existing Spring webapp that ran on a different container before (weblogic), to run on Tomcat. Working on it in Eclipse, I've gotten all of the compile errors out, and I was able to add the webapp to my Tomcat server instance in the "Servers" view. I started the server

Clustering considerations - single server, multiple Tomcat instances - in the cloud

I'm trying to think through the security implications of this configuration: a single cloud server (Digital Ocean) with 2 Tomcat 8.5 instances in a cluster, for session replication. I can bind the Receiver element to 127.0.0.1, which I think should protect the actual session data from prying