GZIP Compression / Deflate - Linux Shared Hosting

This article applies to our Linux Shared Hosting servers, where browser content compression/mod_deflate is enabled. 

[Pay particular attention to the "PHP: ob_start(ob_gzhandler)" section]

GZIP Compression (mod_deflate)

It is possible to utilize mod_deflate with your website, however you will need to implement the correct configuration that suits your website - where:

• You may need to implement .htaccess directives to suit your deployment:
• See Sample Rules below.
• You may need to install plugins to utilize mod_deflate:
• See Dynamic Content below.

IMPORTANT NOTE:

Implementing the required directives for your scenario are outside our scope, as such you will need to consult the support documentation/forums etc. of the website/installation/plugins to determine how to enable GZIP compression.

Dynamic Content

Both the .htaccess file and website have to be crafted in such a way to enable GZIP compression.

In the case of Wordpress, Joomla and other CMS, you typically will need to either install a caching plugin - or similar, or enable functions in the installation, to allow for GZIP compression of the Dynamic content.

As an example for Wordpress, the following popular plugins can cater for this:

• WP Super Cache
• W3 Total Cache

Use these plugins at your own risk.

IMPORTANT NOTE:

Some plugins do not output the minimal rules required for Static file compression, such as the sample rules below; you may need to add these also alongside your plugin's rules to enable compression on static files.

PHP: ob_start(ob_gzhandler)

There is also cases where some test websites, and even the plugin themselves, may not pickup that the "Dynamic"/HTML content is compressed; to resolve this you simply add the following to a "php" file that is loaded by the website - usually a configuration file.

ob_start("ob_gzhandler");

For instance you can add the following to the top of your Wordpress "wp-config.php" file:

<?php

ob_start("ob_gzhandler"); 

If using the following plugins you must add the above to your "wp-config.php" file:

• WP Super Cache
• Hummingbird
• WP Rocket

Sample Rules

The following .htaccess directives are typical for common static files: 

<IfModule mod_deflate.c>
# Compress HTML, CSS, JavaScript, Text, XML and fonts
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE application/x-font
AddOutputFilterByType DEFLATE application/x-font-opentype
AddOutputFilterByType DEFLATE application/x-font-otf
AddOutputFilterByType DEFLATE application/x-font-truetype
AddOutputFilterByType DEFLATE application/x-font-ttf
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE font/opentype
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/ttf
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/xml

# Remove browser bugs (only needed for really old browsers)
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4\.0[678] no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
Header append Vary User-Agent
</IfModule>

Notes:

• Testing Dynamic Content may show that GZIP compression is NOT enabled:
• As such, the best way to test these directives is to check against a static file e.g. a html file.
• For example: domain.tld/readme.html
• Note: You will need to create the file, if it does not exist.
• If you find that the directives enable GZIP for static files, but not Dynamic Content, then you will need to add additional directives/plugins etc. to allow for this.
• .htaccess directives apply from the top folder down i.e.
• If you place the directives in the httpdocs, they will apply to all locations under that folder.
• However, you can potentially override them in .htaccess files below that location.

If you require further assistance with this, please email help@blacknight.com with a brief explanation of the issue and examples/errors which can help replicate the issue.