Gzip compression is a process where data is compressed on the server side and then decompressed by the client (such as a browser). Enabling gzip compression not only saves network bandwidth but also speeds up the loading of applications, although it consumes some CPU resources on the server. The diagram below illustrates a typical HTTP request and response flow, showing how an original 100KB HTML file is reduced to just 10KB after gzip compression.

Before enabling compression:

After enabling compression:

Apache and Nginx are two widely used web servers on Linux cloud servers. The following describes how to enable gzip compression on these two web servers.

Apache

Add the following code block to the Apache configuration file:

<IfModule mod_deflate.c>
    # compress html, css, javascript, text, xml and fonts
    AddOutputFilterByType DEFLATE application/javascript
    AddOutputFilterByType DEFLATE application/rss+xml
    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

    # you can also compress by file type/extension:
    <files *.html>
        SetOutputFilter DEFLATE
    </files>
        </IfModule>

Nginx

For Nginx servers, gzip is enabled by default. This can be confirmed by checking the Nginx configuration file.

##
# Gzip Settings
##

gzip on;
gzip_disable "msie6";

gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;