can't set JAVA_HOME for Tomcat on Ubuntu

why is Tomcat not getting my JAVA_HOME path?

This happens at time when you have installed a java runtime version greater than 11. The tomcat server start script that tries to locate the java location does not include the java runtime version that is running on your Ubuntu installation. The error line should show you the location of the start script that failed. It might look as below;

Process: 9728 ExecStart=/bin/sh /usr/libexec/tomcat9/tomcat-start.sh (code=exited, status=1/FAILURE)

If you open that file, the tomcat-start.sh with a text editor such as nano, you'll notice there a line that tries to locate the java runtime. It is might look as below

This tomcat-locate-java.sh is the file we want to edit. Open it in a text editor such as nano.

Add your java version in the code where it lists the java version. In this case, let us add a java-17 runtime that was installed using the opejdk. In the code below we add 17 just before 11.

Then in the loop where it loops through possible java directories, add the correct wildcard that matches your java. We add below java 17 installed through the openjdk project.

The above line was added since my installed java runtime was java-17-openjdk-amd64. You see your runtime or java installation by running the command which java on a terminal.

You can then restart the tomcat service.