I want to run Tomcat 9 as a specific utility user (Ubuntu 20.04).
As recently as Tomcat 7, this could be accomplished by setting the TOMCAT7_USER and TOMCAT7_GROUP parameters in /etc/default/tomcat7/.
The file /etc/default/tomcat9 exists by default, but it did not contain user/group parameters. I tried adding the parameters TOMCAT9_USER / TOMCAT9_GROUP and TOMCAT_USER / TOMCAT_GROUP to it, restarting Tomcat each time, but the Tomcat process continues to be owned by the 'tomcat' user instead of the one I specify in this file.
I can find zero documentation on these parameters for Tomcat 9, so I have to assume that Tomcat 9 no longer recognizes these parameters. I also find zero documentation on the general problem of running Tomcat 9 as a different user.
How do I run Tomcat 9 as a different user?