On CentOS 7 server, after adding SSL virtualhost entry, i got error

Jul 16 10:27:56 mon1 httpd[6620]: AH00526: Syntax error on line 359 of /etc/httpd/conf/httpd.conf:
Jul 16 10:27:56 mon1 httpd[6620]: Invalid command ‘SSLEngine’, perhaps misspelled or defined by a module not included in the server configuration

This is because Apache SSL module was not installed on the server. You can list all modules enabled in Apache with command

httpd -M

To install apache ssl module, run

yum install mod_ssl

Now restart apache with command

service httpd restart

Now verify if mod_ssl enabled with command

[root@mon1 ~]# httpd -M  | grep ssl
 ssl_module (shared)
[root@mon1 ~]#