When using the internal ELB with Apache 2.4 and Tomcat integration, a "too long" error occurs

I'm Ito, an infrastructure engineer.
a web server receives access requests and then proxies those requests to the application server behind it
it's common to see a setup where

In that case, considering availability, it's better to make each server redundant, right?
So, this is the configuration.

using Apache as the web server and Tomcat as the application server
A common configuration involves

So, I ran into a problem when Apache was throwing it to tomcat, so I'd like to leave the solution here

I got stuck with ProxyPass settings

Write a statement in the Apache virtual host that will route received requests to Tomcat

ProxyPass / ajp://internal-elb-xxxxxxxxxxxxxx.ap-northeast-1.elb.amazonaws.com:8009/

ProxyPass is used to forward incoming requests to port 8009 of AJP.
"internal-elb-~~" refers to the internal ELB.

However, if you run a syntax check on Apache in this state, the following error will be output:

# httpd -t ProxyPass worker hostname (internal-elb-xxxxxxxxxxxxxx.ap-northeast-1.elb.amazonaws.com) too long

The hostname being sent to ProxyPass is too long...
But even if they say that, the hostname of the internal ELB looks like this, and the IP address isn't fixed, so what am I supposed to do
?!

Rewrite rules

In this configuration, it's fine if ProxyPass sends the requests directly to Tomcat, so
I changed the rules as follows.

RewriteEngine on RewriteRule ^/(.*)$ ajp://internal-elb-xxxxxxxxxxxxxx.ap-northeast-1.elb.amazonaws.com:8009/$1 [P,L]

We'll use a rewrite rule.
The rewrite rule is to send the message to AJP if it comes to all recipients.

Now Apache requests can be successfully sent to Tomcat (internal ELB)