Apache does not start after installing the web server. (CentOS 7)
● httpd.service - The Apache HTTP Server
Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Sat 2020-03-28 12:18:22 MSK; 16ms ago
Docs: man:httpd.service(8)
Process: 30144 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=1/FAILURE)
Main PID: 30144 (code=exited, status=1/FAILURE)
Status: "Reading configuration..."
Mar 28 12:18:22 box-40395.localdomain systemd[1]: Starting The Apache HTTP Server...
Mar 28 12:18:22 box-40395.localdomain httpd[30144]: AH00526: Syntax error on line 103 of /etc/httpd/conf.d/ssl.conf:
Mar 28 12:18:22 box-40395.localdomain httpd[30144]: SSLCertificateFile: file '/etc/pki/tls/certs/localhost.crt' does not exist or is empty
Mar 28 12:18:22 box-40395.localdomain systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
Mar 28 12:18:22 box-40395.localdomain systemd[1]: Failed to start The Apache HTTP Server.
Mar 28 12:18:22 box-40395.localdomain systemd[1]: Unit httpd.service entered failed state.
Mar 28 12:18:22 box-40395.localdomain systemd[1]: httpd.service failed.
The error message is very clear:
SSLCertificateFile: file
/etc/pki/tls/certs/localhost.crtdoes not exist or is empty
Remove this invalid configuration or add missing/fix existing certificate file. Either way to have to fix the configuration before Apache can start.
Obtaining an SSL certificate is out of the scope for StackOverflow. There're plenty of resources on the web, you can try on ServerFault too…
When you're done, simply sudo systemctl start httpd to start Apache.