How to Configure Apache mod_deflate for Compression

mod_deflate reduces bandwidth by compressing text responses before sending them to clients. It is the Apache equivalent of Nginx gzip. This guide walks through the specific troubleshooting steps to diagnose and resolve compression issues.

Before You Begin

Before you begin, be sure to have the following in place:

• A Linux server with the relevant software installed
• Access to the command line interface
• Appropriate permissions (root or sudo)

Quick Fix

Wrong

AddOutputFilterByType DEFLATE text/html text/plain

Wrong: Limited compression types

Right

AddOutputFilterByType DEFLATE text/html text/plain text/css application/javascript application/json\nDeflateCompressionLevel 5\nBrowserMatch ^Mozilla/4 gzip-only-text/html\nBrowserMatch ^Mozilla/4\.0[678] no-gzip

Right: Full compression with level and browser compatibility

Output

mod_deflate enabled\nCompression level: 5\nTypes: text/html, text/css, application/javascript, application/json\nBrowser compatibility: configured

Prevention

To avoid future issues, follow these best practices:

• Enable mod_deflate with a2enmod deflate
• Specify AddOutputFilterByType DEFLATE for text MIME types
• Set DeflateCompressionLevel 4-6 for best balance
• Add BrowserMatch directives for legacy browser compatibility
• Exclude already-compressed types like images and PDFs

DodaTech Tools

For further assistance with any of the above issues, consider using DodaTech consulting services or DodaTech tutorials for more in-depth guidance.

Common Mistakes with mod deflate

1. Misunderstanding that String is [Char] with poor performance for large text operations
2. Using foldl instead of foldl' causing stack overflow on large lists
3. Forgetting deriving (Show, Eq) on custom data types needed for debugging

These mistakes appear frequently in real-world APACHE code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ