I observe a problem when using Apache's httpd and Tomcat on CentOS 7. Both are running on the same host, both installed from official repositories. httpd does SAML with mod_auth_mellon and proxies to the backend web app, running in Tomcat.
Initial situation:
- Both services are stopped
First use case:
- systemctl start httpd
- systemctl start tomcat
- --> works
Second use case:
- systemctl start tomcat
- systemctl start httpd
- --> does NOT work
Error message:
Aug 09 14:03:08 prod2.localdomain systemd[1]: Starting The Apache HTTP Server...
-- Subject: Unit httpd.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit httpd.service has begun starting up.
Aug 09 14:03:09 prod2.localdomain systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
Aug 09 14:03:09 prod2.localdomain kill[55952]: kill: cannot find process ""
Aug 09 14:03:09 prod2.localdomain systemd[1]: httpd.service: control process exited, code=exited status=1
Aug 09 14:03:09 prod2.localdomain systemd[1]: Failed to start The Apache HTTP Server.
-- Subject: Unit httpd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit httpd.service has failed.
--
-- The result is failed.
Aug 09 14:03:09 prod2.localdomain systemd[1]: Unit httpd.service entered failed state.
Aug 09 14:03:09 prod2.localdomain systemd[1]: httpd.service failed.
There are no port collisions, checked it with netstat -nalp
. httpd is only bound to port 80, tomcat only to 8080 and 8009.
Therefore two questions:
- What does systemd try to kill?
- What is happening?