Apache Static File Serving and Cache Control

This chapter covers efficient static file serving and proper browser cache control in Apache. Using mod_expires, mod_deflate, and ETag settings can dramatically improve web performance.

Apache Static File Serving Basics

Apache maps requested URLs to the filesystem by combining them with DocumentRoot.

<VirtualHost *:80>
    ServerName example.com
    DocumentRoot /var/www/html

    <Directory /var/www/html>
        Options -Indexes +FollowSymLinks
        AllowOverride None
        Require all granted
    </Directory>
</VirtualHost>

mod_expires — Cache Expiry Headers

sudo a2enmod expires
sudo systemctl reload apache2

<IfModule mod_expires.c>
    ExpiresActive On
    ExpiresDefault "access plus 1 week"

    ExpiresByType text/html                  "access plus 0 seconds"
    ExpiresByType text/css                   "access plus 1 year"
    ExpiresByType application/javascript     "access plus 1 year"
    ExpiresByType image/jpeg                 "access plus 1 month"
    ExpiresByType image/png                  "access plus 1 month"
    ExpiresByType image/webp                 "access plus 1 month"
    ExpiresByType image/svg+xml              "access plus 1 month"
    ExpiresByType image/x-icon               "access plus 1 year"
    ExpiresByType font/woff                  "access plus 1 year"
    ExpiresByType font/woff2                 "access plus 1 year"
    ExpiresByType application/json           "access plus 0 seconds"
</IfModule>

mod_headers — Fine-Grained Cache-Control

sudo a2enmod headers
sudo systemctl reload apache2

<IfModule mod_headers.c>
    # Hashed JS/CSS — 1 year strong cache (immutable)
    <FilesMatch "\.[0-9a-f]{8,}\.(js|css)$">
        Header set Cache-Control "max-age=31536000, public, immutable"
    </FilesMatch>

    <FilesMatch "\.(js|css)$">
        Header set Cache-Control "max-age=31536000, public"
    </FilesMatch>

    <FilesMatch "\.(png|jpg|jpeg|gif|webp|ico|woff|woff2|ttf|svg)$">
        Header set Cache-Control "max-age=2592000, public"
    </FilesMatch>

    <FilesMatch "\.html$">
        Header set Cache-Control "no-cache, no-store, must-revalidate"
        Header set Pragma "no-cache"
        Header set Expires "0"
    </FilesMatch>

    <LocationMatch "^/api/">
        Header set Cache-Control "no-cache, no-store, must-revalidate"
    </LocationMatch>
</IfModule>

ETag Configuration

# Default ETag (includes inode — problematic in distributed servers)
FileETag MTime Size

# Recommended for distributed/load-balanced environments
FileETag MTime Size
# or disable completely:
FileETag None

Distributed environment warning: Default ETag includes inode numbers, which differ across servers. Use FileETag MTime Size or FileETag None to avoid cache mismatches.

mod_deflate — Gzip Compression

sudo a2enmod deflate
sudo systemctl reload apache2

<IfModule mod_deflate.c>
    AddOutputFilterByType DEFLATE text/html text/plain text/css
    AddOutputFilterByType DEFLATE application/javascript application/json
    AddOutputFilterByType DEFLATE image/svg+xml font/woff font/woff2
    SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|webp|zip|gz|bz2)$ no-gzip dont-vary
    Header append Vary Accept-Encoding
    DeflateCompressionLevel 6
</IfModule>

Comprehensive Configuration Example

<VirtualHost *:443>
    ServerName static.example.com
    DocumentRoot /var/www/static

    SSLEngine on
    SSLCertificateFile    /etc/letsencrypt/live/static.example.com/fullchain.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/static.example.com/privkey.pem

    <Directory /var/www/static>
        Options -Indexes -MultiViews +FollowSymLinks
        AllowOverride None
        Require all granted
    </Directory>

    <IfModule mod_deflate.c>
        AddOutputFilterByType DEFLATE text/html text/css application/javascript application/json image/svg+xml font/woff font/woff2
        DeflateCompressionLevel 6
        Header append Vary Accept-Encoding
    </IfModule>

    <IfModule mod_expires.c>
        ExpiresActive On
        ExpiresByType text/html            "access plus 0 seconds"
        ExpiresByType text/css             "access plus 1 year"
        ExpiresByType application/javascript "access plus 1 year"
        ExpiresByType image/jpeg           "access plus 1 month"
        ExpiresByType image/png            "access plus 1 month"
        ExpiresByType font/woff2           "access plus 1 year"
    </IfModule>

    <IfModule mod_headers.c>
        <FilesMatch "\.(js|css)$">
            Header set Cache-Control "max-age=31536000, public, immutable"
        </FilesMatch>
        <FilesMatch "\.html$">
            Header set Cache-Control "no-cache"
        </FilesMatch>
    </IfModule>
</VirtualHost>

Summary

Optimization	Module	Effect
Cache expiry headers	`mod_expires`	Fewer requests from repeat visitors
Fine-grained Cache-Control	`mod_headers`	Immutable and precise cache policies
Gzip compression	`mod_deflate`	50–80% reduction in text transfer size
ETag adjustment	`FileETag`	Prevents unnecessary revalidation in distributed environments
Disable directory listing	`Options -Indexes`	Security hardening

Apache Static File Serving Basics​

mod_expires — Cache Expiry Headers​

mod_headers — Fine-Grained Cache-Control​

ETag Configuration​

mod_deflate — Gzip Compression​

Comprehensive Configuration Example​

Summary​