Apache: edit to .conf file produces "Invalid command 'Header'"

In Magento CE, I'd like to install an add-on to Extendware Page Cache called Lightening Cache.

It requires editing the Apache configuration inside the virtual host definition for the site, by adding:

RewriteEngine On
RewriteMap ewpchash prg:/home/.../shell/extendware/ewpagecache/apache/md5.php

RewriteCond %{REQUEST_METHOD} !POST
RewriteCond %{REQUEST_URI} !\.(js|css|png|jpg|jpeg|ico|gif)$ [NC]
RewriteCond %{DOCUMENT_ROOT}%{SCRIPT_FILENAME} !-f
RewriteCond ${ewpchash:%{HTTPS};~;%{HTTP_HOST};~;%{REQUEST_URI};~;%{QUERY_STRING};~;%{HTTP:Cookie};~;%{SCRIPT_FILENAME};~;%{REMOTE_ADDR};~;%{HTTP_USER_AGENT}} -f
RewriteRule ^(.*)$ ${ewpchash:%{HTTPS};~;%{HTTP_HOST};~;%{REQUEST_URI};~;%{QUERY_STRING};~;%{HTTP:Cookie};~;%{SCRIPT_FILENAME};~;%{REMOTE_ADDR};~;%{HTTP_USER_AGENT}} [NC,L]
<FilesMatch "\.(html)$">
     Header unset Cache-Control
     Header unset Expires
     Header append Expires "Thu, 19 Nov 1981 08:52:00 GMT"
     Header append Cache-Control "must-revalidate"
</FilesMatch>

I have added this to the bottom of /etc/apache2/sites-enabled/site.conf.

When I run the command apachectl graceful, I receive the error:

> AH00526: Syntax error on line 53 of > /etc/apache2/sites-enabled/site.conf: Invalid command 'Header', > perhaps misspelled or defined by a module not included in the server > configuration Action 'graceful' failed. The Apache error log may have > more information.

Site is running Apache 2.4

Have I done something wrong?

In order to use Header directive in apache you have to load mod_header module. You can test if module is loaded or not by :-

apache2ctl -M | grep headers_module

find / -name mod_headers.so

If it is loaded you will see something like :-

headers_module (shared)

/usr/lib/apache2/modules/mod_headers.so

If you see no output of find command than load that module directly in your apache conf file. Just append below line :-

LoadModule headers_module modules/mod_headers.so

>> Note :- mod_header is available as base module in apache. So you don't need to install it explicitly.

Issue following command :-

a2enmod headers

Restart web service

apache2ctl restart