Browsing to http://IP_address doesn’t work because there is nothing listening on port 80 (tomcat is listening on 8080). I would recommend installing nginx and configuring it a reverse proxy so that it forwards requests from port 80 to port 8080.

Run the following command:

sudo apt-get install nginx

Then, edit /etc/nginx/sites-enabled/default and replace its contents with the following:

upstream tomcat {
    server http://localhost:8080;
}

server {
    listen 80;
    location / {
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Server $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://tomcat;
    }
}

Finally, restart nginx:

sudo service nginx restart