Lighttpd

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#!rst

===================
the Proxy Interface ===================

----------------------
Module: mod_proxy_core
----------------------

.. contents:: Table of Contents

Description ===========

FastCGI, SCGI, HTTP, ... are doing the simple job: they forward the HTTP-request to a backend and send the response back to the server. They just use another protocol to encode the data.

• FastCGI was developed by http://www.fastcgi.com/ and is a binary container around HTTP requests which reduces the parsing overhead.
• SCGI similar to HTTP and only adds a length header for the HTTP-header. http://www.mems-exchange.org/software/scgi/ says "The SCGI protocol is a replacement for the Common Gateway Interface (CGI) protocol. It is a standard for applications to interface with HTTP servers. It is similar to FastCGI but is designed to be easier to implement."
• for HTTP we support HTTP/1.0 and HTTP/1.1 on the backend side
• AJP13 is the Apache JServ Protocol version 1.3 (see http://tomcat.apache.org/connectors-doc/common/ajpv13a.html), implemented by mod_jk in the apache world.

A small guide shall help you to choose the right protocol for your needs.

======== ============= =============== ==========
Protocol preferred by binary protocol keep-alive ======== ============= =============== ==========
HTTP mongrel no yes
SCGI WSGI (python) not really no
FastCGI PHP, rails yes yes
AJP13 Tomcat yes don't know ======== ============= =============== ==========

Installation
------------

If you want to use mod-proxy-core you have to load it first. Each protocol is a module too and has to be loaded
after the core-module.: ::

server.modules = (
    ..., 
    "mod_proxy_core",
    "mod_proxy_backend_http",
    ... )

Options =======

proxy-core.balancer
might be one of 'round-robin', 'sqf' or 'carp'.

proxy-core.protocol
might be one of 'http', 'fastcgi', 'ajp13' or 'scgi'. Make sure you load the backend
modules (see mod_proxy_backend_<name>)

proxy-core.backends
tell the module where to send Proxy requests to.
It is a list of hostname/ip address/unix-domain socket

proxy-core.max-pool-size
max size for pool of connections to backends.

proxy-core.check-local
enable checking for url file in local document-root. Enable this for php

proxy-core.allow-x-sendfile
enables use of "X-Sendfile/X-LIGHTTPD-Sendfile/X-LIGHTTPD-send-tempfile" headers.

See: 

• http://blog.lighttpd.net/articles/2006/07/22/mod_proxy_core-got-x-sendfile-support
• http://blog.lighttpd.net/articles/2006/11/29/faster-fastcgi

proxy-core.allow-x-rewrite
enables use of "X-Rewrite"

See:
  * http://blog.lighttpd.net/articles/2006/07/22/x-sendfiles-new-friend-x-rewrite

proxy-core.rewrite-request
rewrite request headers or request uri.

proxy-core.rewrite-response
rewrite response headers.

Example: ========

Using lighttpd + mod_proxy_core in front of 8 Squids which handle the
caching of dynamic content for you. All requests for the host
www.example.org should be forwarded to the proxy. All proxies
listen on port 80 for requests. ::

server.modules  += ( "mod_proxy_backend_http" )
  $HTTP["host"] == "www.example.org" {
    proxy-core.protocol = "http" 
    proxy-core.balancer = "carp" 
    proxy-core.backends = ( "10.0.0.10",
                            "10.0.0.11",
                            "10.0.0.12",
                            "10.0.0.13",
                            "10.0.0.14",
                            "10.0.0.15",
                            "10.0.0.16",
                            "10.0.0.17" )
  }

If one of the hosts goes down the all requests for this one server are
moved equally to the other servers. If you want to know more about
the algorithm used here google for 'Microsoft CARP'.

for php using unix-domain socket "/tmp/php-fastcgi.sock" ::

server.modules  += ( "mod_proxy_backend_fastcgi" )
  $HTTP["url"] =~ "\.php$" {
    proxy-core.balancer = "round-robin" 
    proxy-core.protocol = "fastcgi" 
    proxy-core.check-local = "enable" 
    proxy-core.allow-x-sendfile = "enable" 
    proxy-core.backends = ( "unix:/tmp/php-fastcgi.sock" )
    proxy-core.max-pool-size = 16
  }

for SCGI ::

server.modules  += ( "mod_proxy_backend_scgi" )
  $HTTP["url"] =~ "\.scgi$" {
    proxy-core.balancer = "round-robin" 
    proxy-core.protocol = "scgi" 
    proxy-core.check-local = "enable" 
    proxy-core.allow-x-sendfile = "enable" 
    proxy-core.backends = ( "127.0.0.1:9090" )
    proxy-core.max-pool-size = 16
  }

for http-proxy with host and file-extension conditionals ::

server.modules  += ( "mod_proxy_backend_http" )
  $HTTP["host"] == "www.example.org" {
    proxy-core.protocol = "http" 
    proxy-core.balancer = "carp" 
    $HTTP["url"] =~ "\.php$" {
      proxy-core.backends = ( "10.0.0.10:80" )
    }
    else $HTTP["url"] =~ "\.scgi$" {
      proxy-core.backends = ( "10.0.0.11:80" )
    }
  }

Reverse-Proxying ::

server.modules  += ( "mod_proxy_backend_http" )
  $HTTP["url"] =~ "^/proxyme(/|$)" {
    proxy-core.balancer = "round-robin" 
    proxy-core.protocol = "http" 
    proxy-core.backends = ( "en.wikipedia.org" )
    proxy-core.rewrite-response = (
      "Location" => ( "^http://en.wikipedia.org/(.*)" => "http://127.0.0.1:1025/proxyme/$1" ),
    )
    proxy-core.rewrite-request = (
      "_uri" => ( "^/proxyme/?(.*)" => "/$1" ),
      "Host" => ( ".*" => "en.wikipedia.org" ),
    )
  }

for proxying to Tomcat using AJP13 protocol ::

server.modules  += ( "mod_proxy_backend_ajp13" )
  $HTTP["url"] =~ "^/tomcat/" {
    proxy-core.balancer = "round-robin" 
    proxy-core.protocol = "ajp13" 
    proxy-core.backends = ( "localhost:8009" )
    proxy-core.max-pool-size = 16
  }

}}}