How to Enable Expires Headers in Apache

Apache is a highly flexible, powerful, and open-source HTTP server software that is widely used for hosting websites. One of its capabilities is to manipulate HTTP headers in responses, a feature which can significantly improve the performance of your website.

Among these manipulations, enabling the ‘expire headers’ is an effective technique to manage the caching behavior of your website. Essentially, expire headers tell the browser how long a particular file should be cached. This means that subsequent requests for the same file are served from the cache, saving bandwidth and improving the speed of your site.

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In this article, we are going to discuss how to enable expire headers in Apache.

Preparation

Before we begin, you need to ensure that you have administrator access to your Apache server because you need to modify the Apache configuration file.

Also, make sure that the ‘mod_expires’ Apache module is enabled. You can check whether it’s enabled by running the following command:

apachectl -M | grep expires 

If the module is enabled, you will see expires_module (shared) in the output. If not, you can enable it by running:

sudo a2enmod expires 

Remember to restart Apache after enabling the module:

sudo systemctl restart apache2 

Setting up the Expires Header in Apache

There are two main ways to enable expire headers in Apache: through the main Apache configuration file (httpd.conf or apache2.conf), or via the .htaccess file in the root directory of your website.

Method 1: Using the Main Apache Configuration File

1. Open the Apache configuration file. Its location varies depending on your operating system. It’s usually located in /etc/httpd/conf/httpd.conf or /etc/apache2/apache2.conf. Use a text editor to open it, for example:

   sudo nano /etc/apache2/apache2.conf 
   

2. Add the following lines to the configuration file:
   <IfModule mod_expires.c> ExpiresActive On ExpiresDefault "access plus 2 days" ExpiresByType image/jpg "access plus 1 year" ExpiresByType image/jpeg "access plus 1 year" ExpiresByType image/gif "access plus 1 year" ExpiresByType image/png "access plus 1 year" ExpiresByType text/css "access plus 1 month" ExpiresByType text/html "access plus 2 days" ExpiresByType application/pdf "access plus 1 month" ExpiresByType text/x-javascript "access plus 1 month" ExpiresByType application/x-shockwave-flash "access plus 1 month" ExpiresByType image/x-icon "access plus 1 year" </IfModule>

   1 2 3 4 5 6 7 8 9 10 11 12 13 14

   <IfModule mod_expires.c>     ExpiresActive On     ExpiresDefault "access plus 2 days"     ExpiresByType image/jpg "access plus 1 year"     ExpiresByType image/jpeg "access plus 1 year"     ExpiresByType image/gif "access plus 1 year"     ExpiresByType image/png "access plus 1 year"     ExpiresByType text/css "access plus 1 month"     ExpiresByType text/html "access plus 2 days"     ExpiresByType application/pdf "access plus 1 month"     ExpiresByType text/x-javascript "access plus 1 month"     ExpiresByType application/x-shockwave-flash "access plus 1 month"     ExpiresByType image/x-icon "access plus 1 year" </IfModule>

3. Save and close the file.
4. Restart Apache to implement the changes:

   sudo systemctl restart apache2
   

Method 2: Using the .htaccess file

1. Open the .htaccess file in your website’s root directory. If it doesn’t exist, create it.
2. Add the same lines as above to the .htaccess file.
3. There is no need to restart Apache if you’re using a .htaccess file. The changes take effect immediately.

The ExpiresByType directive allows you to set expiry times for specific file types. In the examples above, JPEG, JPG, GIF, and PNG files are set to be cached for 1 year. HTML files are set to be cached for 2 days, CSS and JavaScript files are set to be cached for 1 month, and so on.

By customizing these directives according to the types of files that your website serves, you can optimize the caching behavior and performance of your site.

Conclusion

Enabling expire headers in Apache is an effective way to improve the performance of your website by managing the caching behavior of the site. By setting expiry times for different file types, you can save bandwidth and improve the speed of your website. Remember to test the changes after you implement them to ensure that everything works as expected.