If your using enterprise linux 7 the TLS module should be enabled by default but you might want to double check.
Here is what I have for a TLS config.
Make sure that your www-user has read permissions to the CERT files.
As normal you’ll need to restart apache to start the new virtual host.
Once you have the SSL endpoint working you can change your HTTP virtual host to redirect to 443.
https://wiki.apache.org/httpd/RedirectSSL
/etc/httpd/conf.d/librenms-ssl.conf
<IfModule mod_ssl.c>
<VirtualHost *:443>
#Set HTTP STS Header
#Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
#Set Clickjacking Header
#Header always append X-Frame-Options SAMEORIGIN
#Set XSS Reject Header
#Header set X-XSS-Protection "1; mode=block"
#SSL Config
SSLEngine on
SSLCertificateFile /var/local/cert/librenms.crt
SSLCertificateKeyFile /var/local/cert/librenms.key
SSLCertificateChainFile /var/local/cert/ca.crt
SSLProtocol ALL -SSLv2 -SSLv3
SSLHonorCipherOrder On
SSLCipherSuite ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
<FilesMatch "\.(cgi|shtml|phtml|php)$">
SSLOptions +StdEnvVars
</FilesMatch>
#IE Downgrade mitigation
BrowserMatch "MSIE [2-6]" \
nokeepalive ssl-unclean-shutdown \
downgrade-1.0 force-response-1.0
BrowserMatch "MSIE [17-9]" ssl-unclean-shutdown
DocumentRoot /opt/librenms/html/
ServerName librenms.<domain>
CustomLog /opt/librenms/logs/access_log combined
ErrorLog /opt/librenms/logs/error_log
AllowEncodedSlashes NoDecode
<Directory "/opt/librenms/html/">
Require all granted
AllowOverride All
Options FollowSymLinks MultiViews
</Directory>
</VirtualHost>
</IfModule>