Up to and including version 17.5 Plesk Onyx came with a Tomcat installation, which is no longer supported from version 17.8. Thus no .war files can be deployed and executed anym
The downside of using Plesk's "Docker proxy rules" is multiple domains can't share one docker.
In Plesk 17.8 here's what worked best for me...
Using ssh, install Tomcat on port 8080.
Delete all demo apps from Tomcat webapp folder
Copy my app war files to Tomcat webapp folder
Log in to Plesk
For each domain with a Tomcat webapp, click "Apache & nginx Settings" for that domain, scroll down, under "Additional nginx directives" Add
location /app1 {
proxy_pass http://127.0.0.1:8080;
}
Every webapp name has be unique. Works with Let's Encrypt so
https://example1.com/app1 shows http://127.0.0.1:8080/app1
https://example2.com/app2 shows http://127.0.0.1:8080/app2