Apache 2.4 – Fix Apache Not Starting with Mod_Session_Crypto

apache-2.4

When I enable mod_session_crypto by uncommenting it from the config, apache server fails to start. I found the following error from the journalctl:

Jan 09 12:27:39 dbserver1 systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
Jan 09 12:27:39 dbserver1 kill[18321]: kill: cannot find process ""
Jan 09 12:27:39 dbserver1 systemd[1]: httpd.service: control process exited, code=exited status=1
Jan 09 12:27:39 dbserver1 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.
Jan 09 12:27:39 dbserver1 systemd[1]: Unit httpd.service entered failed state.
Jan 09 12:27:39 dbserver1 systemd[1]: httpd.service failed.
Jan 09 12:27:39 dbserver1 polkitd[1053]: Unregistered Authentication Agent for unix-process:18219:214619083 (system bus name :1

I cannot figure out what's wrong from it.

When I disable the mod_session_crypto, mod_auth_form is not creating cookie – seems like it's refusing to create a cookie with unencrypted username and password when I use AuthProvider ldap. Worked fine with AuthProvider basic.

This setting worked just fine on my other computer I use for development.

Dev PC (works):
CentOS 7.4.1708
Apache 2.4.6-67.el7
mod_session 2.4.6-67.el7

Production PC (doesn't start):
CentOS 7.5.1808
Apache 2.4.6-80.el7
mod_session 2.4.6-80.el7

As you can see there's a slight difference in OS version. Beside that, I cannot find anything different.

Best Answer

Thanks to the symcbean's tip, I found the following error message logged in the apache error log:

[Wed Jan 09 12:49:53.410386 2019] [session_crypto:error] [pid 30523] (20019)DSO load failed: AH01845: The crypto library 'openssl' could not be loaded: /usr/lib64/apr-util-1/apr_crypto_openssl-1.so: cannot open shared object file: No such file or directory (apr_crypto_openssl-1.so: 0)

According to the bug report here, all that's needed is to install apr-util-openssl package, e.g. with yum install apr-util-openssl.

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