From 087fa3ff5d3f3bdea29513c02e1765c678834a9c Mon Sep 17 00:00:00 2001
From: nisbet-hubbard <87453615+nisbet-hubbard@users.noreply.github.com>
Date: Sat, 2 Nov 2024 23:14:38 +0800
Subject: [PATCH] Documented caching of compressed content.

---
 .../docs/http/caching_compressed_content.xml  | 80 +++++++++++++++++++
 xml/en/docs/index.xml                         |  4 +
 2 files changed, 84 insertions(+)
 create mode 100644 xml/en/docs/http/caching_compressed_content.xml

diff --git a/xml/en/docs/http/caching_compressed_content.xml b/xml/en/docs/http/caching_compressed_content.xml
new file mode 100644
index 00000000..3ceaa97e
--- /dev/null
+++ b/xml/en/docs/http/caching_compressed_content.xml
@@ -0,0 +1,80 @@
+<!DOCTYPE article SYSTEM "../../../../dtd/article.dtd">
+
+<article name="Caching compressed content"
+         link="/en/docs/http/caching-compressed-content.html"
+         lang="en"
+         rev="1">
+
+
+<section>
+
+<para>
+It has often been asked whether nginx is able to cache the
+results of on-the-fly compression.
+This would not only save the hassle of generating
+<literal>.gz</literal> files manually or the latency and
+CPU cycles required for compressing on the fly, but also
+make it possible to benefit from the performance
+improvements offered by
+<link url="https://www.f5.com/company/blog/nginx/improving-nginx-performance-with-kernel-tls">kTLS
+and SSL_sendfile()</link>, which have to be disabled when the
+gzip filter is in use.
+</para>
+
+<para>
+As an example, a minimal configuration for an nginx server that
+caches responses from a FastCGI applications such as PHP would
+normally look something like this:
+<programlisting>
+gzip on;
+
+fastcgi_cache_path /var/cache/nginx levels=1:2
+    keys_zone=WORDPRESS:100m inactive=60m;
+  
+location / {
+    try_files $uri /index.php?$args;
+}    
+
+location ~ \.php$ {
+    try_files $uri =404;
+    fastcgi_pass unix:/run/php-fpm.sock;
+    include fastcgi_params;
+    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
+    fastcgi_cache WORDPRESS;
+}
+</programlisting>
+This would only cache uncompressed responses, however.
+To cache gzip-compressed responses, we need to set up
+a dedicated caching server using
+<link url="https://nginx.org/en/docs/http/ngx_http_proxy_module.html">ngx_http_proxy_module</link>:
+<programlisting>
+map $http_accept_encoding $encoding {
+    default       "";
+    ~.*gz.*       gz;
+}
+
+server {
+    …
+    location / {
+        proxy_pass http://unix:/run/nginx.sock;
+        proxy_cache WORDPRESS;
+        proxy_cache_key "$scheme$request_method$host$request_uri $encoding";
+        proxy_set_header Accept-Encoding "$encoding";
+        proxy_set_header Host $host; 
+    }
+}
+
+server {
+    listen unix:/run/nginx.sock;
+    gzip on;
+    …
+    location ~ \.php$ {
+        try_files $uri =404;
+        fastcgi_pass unix:/run/php-fpm.sock;
+        include fastcgi_params;
+        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
+        fastcgi_param HTTPS on;
+        …
+    }
+}
+</programlisting>
diff --git a/xml/en/docs/index.xml b/xml/en/docs/index.xml
index f7d6f431..b92db33e 100644
--- a/xml/en/docs/index.xml
+++ b/xml/en/docs/index.xml
@@ -145,6 +145,10 @@
 <link doc="http/converting_rewrite_rules.xml"/>
 </listitem>
 
+<listitem>
+<link doc="http/caching_compressed_content.xml"/>
+</listitem>
+
 <listitem>
 <link doc="http/websocket.xml"/>
 </listitem>