Database Diagram:

(diagram image is outdated)

pgadmin ssh:

check: how-to-connect-pgadmin4-to-db-through-ssh-tunnel-with-public-key-authentication

Nginx-keepalive: Here

fail2ban: https://www.digitalocean.com/community/tutorials/how-to-protect-ssh-with-fail2ban-on-ubuntu-14-04

Secure a containerized nodejs application with nginx: Here

Logfiles with logrotate on ubuntu: Here

Secure environment_variables in yaml: Here

log ssh login

$ sudo cat /var/log/auth.log

If you want to check for compromise, look at wtmp (type who), and look at the system logs. Audit records in syslog (like "session opened for user james") will shed some light.

$ who

You could also look for users you do not recognize, and inspect traffic and connections

$ netstat -nvlp