Setting Up Cache Using .htaccess on Linux Server

What is .htaccess?

.htaccess (hypertext access) is a configuration file utilized by Apache web servers to enable decentralized management of server configuration. It allows for directory-level configuration changes and is commonly used to control access, set up redirects, and implement various other functionalities.

Setting Up Cache with .htaccess

To enable caching via .htaccess, follow these steps:

Step 1: Access .htaccess File

Using an FTP client or a file manager provided by your hosting provider, navigate to the root directory of your website. Look for the .htaccess file. If it doesn’t exist, you can create one.

Step 2: Enable Mod_Expires

Ensure that mod_expires is enabled on your server. This module provides the ability to set expiration dates for different types of files. You can enable it by adding the following line to your Apache configuration:

LoadModule expires_module modules/mod_expires.so

Step 3: Configure Cache-Control Headers

Add the following lines to your .htaccess file to define the caching duration for various file types:

 
  # Enable Expires headers
  ExpiresActive On
 
  # Set expiration time for images to 1 year (adjust as needed)
  ExpiresByType image/jpeg "access plus 1 year"
  ExpiresByType image/png "access plus 1 year"
  ExpiresByType image/gif "access plus 1 year"
  ExpiresByType image/svg+xml "access plus 1 year"
 
  # Set expiration time for CSS and JavaScript to 1 week
  ExpiresByType text/css "access plus 1 week"
  ExpiresByType application/javascript "access plus 1 week"
 
  # Set expiration time for HTML and XML to 1 day
  ExpiresByType text/html "access plus 1 day"
  ExpiresByType text/xml "access plus 1 day"
 

Adjust the expiration times according to your specific requirements.

Step 4: Implement ETag

ETag (entity tag) is an HTTP response header that helps in validating cache. Add the following lines to your .htaccess file to implement ETag:

# Enable ETag
Header unset ETag

<IfModule mod_headers.c>
Header set Connection keep-alive

# Cache-control headers
    # 2 HOURS
    #<filesMatch "*">
        Header set Cache-Control "max-age=7200, must-revalidate"
    #</filesMatch>

    # 480 weeks - 290304000
    # 2 WEEKS
    <filesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|swf)$">
        Header set Cache-Control "max-age=1209600, public"
    </filesMatch>

    # 1 DAY
    <filesMatch "\.(css)$">
        Header set Cache-Control "max-age=86400, public, must-revalidate"
        #Header set Cache-Control "max-age=0, public, must-revalidate"
    </filesMatch>

    # 2 DAYS
    <filesMatch "\.(xml|txt)$">
        Header set Cache-Control "max-age=172800, public, must-revalidate"
    </filesMatch>

    # 2 HOURS
    <filesMatch "\.(html|htm)$">
        Header set Cache-Control "max-age=7200, must-revalidate"
    </filesMatch>

    <FilesMatch "\.(gif|jpg|png|ico|css|js|pdf|txt)$">
        Header append Cache-Control "public"
    </FilesMatch>
</IfModule>