ArcGIS Enterprise on Red Hat Linux: Apache Tomcat is not accessible via HTTPS, ArcGIS WebAdaptors not working

[Boke]

Hello Enterprise Community.

My team ran into an issue when deploying ArcGIS Enterprise on RedHat Linux this week. Initially, everything worked fine with Federation being the final checklist item. The federation was pending because the FQDN has not been configured properly to resolve to the machine from a public IP. 

A brief about the environment: 

Number of Machines: 2

Base Arcgis Enterprise Deployment was done on Machine A, and portal and Server on Machine B were joined to the corresponding sites on machine A. Apache Tomcat was deployed and the web adaptors for portal and server were deployed successfully. Like I said, everything was working fine. Portal and Server were accessible via webadaptors from both machine. Due to the inavailability of load balancers, we choose to go ahead with Machine A and we configured the FQDN to resolve to machine A.

The problem:

Recently we discovered the web adaptors no longer work on machine A, no idea how it happened, the infrastructure team said they didn't do anything on the machine. After several troubleshooting, we discovered that the Apache Tomcat service has not been running. So we did some tweaks, and Tomcat is running. Then we notice that Tomcat landing page is only displayed when the protocol is HTTP. Once we put HTTPS in the browser, the webpage displayed is the Red Hat Enterprise Linux Test Page. This is where we are currently stuck. It was working before, but it no longer works. We've adjusted the connectors in the server.xml file to no avail. Calling on anyone here who can help resolve this issue because User acceptability session has been scheduled for next week. We need to have the deployment running this weekend. 

In the screenshot below, the page on the left is displayed wihen we use http://,  the one on the right is when we use https:// 

We know that the web adaptors rely on Tomcat to work, and they will not work without https, hence we want to resolve the Tomcat issue first, and see if our web adaptors will work or we need to reconfigure.

Software versions:

ArcGIS Enterprise 11.1

OS: Red Hat Enterprise 8

Apache: 2.4.37

Tomcat: 9.0.64

Thank you so much in anticipation.

[JeffSmith · Accepted solution]

I suspect you have a port conflict where Apache httpd and Tomcat are both trying to listen on port 443.  That's why you are seeing the RHEL Test Page.  If you are not using the Apache httpd, the easiest fix is to disable that and only run Tomcat.  If you are hosting other apps on Apache httpd, it might be easier to configure Apache as a reverse proxy for Enterprise and not use Tomcat.  Documentation on configuring the reverse proxy can be found here:

https://enterprise.arcgis.com/en/portal/latest/administer/linux/using-a-reverse-proxy-server-with-po...

[Boke]

Thanks @JeffSmith you're right, there was really a conflict. We disabled the httpd service and the tomcat server is working fine now.