SonarQube is listening on the loopback IP address on port 9000. SonarQube is not listening on the external IP address. You want to access the web UI for SonarQube. What should you do?
Install a web server and configure it to connect to port 9000. Here are the details for using Apache web server on a Red Hat derivative (e.g., CentOS/RHEL/Fedora).
1. Run this command: sudo yum -y install httpd
2.a Run this command, but replace x.x.x.x with the external IP address of your server (or the URL that you will present with this server):
sudo vi /etc/httpd/conf.d/sonar.x.x.x.x.conf
2.b. Place these lines in the file (where the top and bottom lines have "VirtualHost" in them):
ProxyPass / http://localhost:9000/
ProxyPassReverse / http://localhost:9000/
2.c. Replace x.x.x.x with the IP address or domain name of your server.
2.d. Replace "firstname.lastname@example.org" with an email address of yours.
3. Run these two commands:
sudo systemctl start httpd
sudo systemctl enable httpd