How to export environment variables to Apache httpd in RHEL

Issue

• How can we export an environment variable to the httpd service and then use it in config files? Is this different between versions of httpd and versions of RHEL?

• We added environment variables to /etc/sysconfig/httpd and this works in RHEL6, but when we systemctl start httpd in RHEL7, we get errors like this:

  systemd[1]: Ignoring invalid environment assignment 'export MY_CUSTOM_VARIABLE=prod.example.com': /etc/sysconfig/httpd
  

• In RHEL7 and RHEL8, custom environment variables in /etc/sysconfig/httpd are seen when using apachectl but aren't seen when starting apache with systemctl start httpd.

• In RHEL7 and RHEL8, custom environment variables in /etc/sysconfig/httpd are seen when using systemctl start httpd but not when using apachectl.