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<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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<modulesynopsis metafile="mod_proxy_scgi.xml.meta">
<name>mod_proxy_scgi</name>
<description>SCGI gateway module for <module>mod_proxy</module></description>
<status>Extension</status>
<sourcefile>mod_proxy_scgi.c</sourcefile>
<identifier>proxy_scgi_module</identifier>
<summary>
<p>This module <em>requires</em> the service of <module
>mod_proxy</module>. It provides support for the
<a href="http://python.ca/scgi/protocol.txt">SCGI protocol, version
1</a>.</p>
<p>Thus, in order to get the ability of handling the SCGI protocol,
<module>mod_proxy</module> and <module>mod_proxy_scgi</module> have to
be present in the server.</p>
<note type="warning"><title>Warning</title>
<p>Do not enable proxying until you have <a
href="mod_proxy.html#access">secured your server</a>. Open proxy
servers are dangerous both to your network and to the Internet at
large.</p>
</note>
</summary>
<seealso><module>mod_proxy</module></seealso>
<seealso><module>mod_proxy_balancer</module></seealso>
<section id="examples"><title>Examples</title>
<p>Remember, in order to make the following examples work, you have to
enable <module>mod_proxy</module> and <module>mod_proxy_scgi</module>.</p>
<example><title>Simple gateway</title>
<highlight language="config">
ProxyPass "/scgi-bin/" "scgi://localhost:4000/"
</highlight>
</example>
<p>The balanced gateway needs <module>mod_proxy_balancer</module> and
at least one load balancer algorithm module, such as
<module>mod_lbmethod_byrequests</module>, in addition to the proxy
modules listed above. <module>mod_lbmethod_byrequests</module> is the
default, and will be used for this example configuration.</p>
<example><title>Balanced gateway</title>
<highlight language="config">
ProxyPass "/scgi-bin/" "balancer://somecluster/"
<Proxy balancer://somecluster>
BalancerMember scgi://localhost:4000
BalancerMember scgi://localhost:4001
</Proxy>
</highlight>
</example>
</section>
<section id="env"><title>Environment Variables</title>
<p>In addition to the configuration directives that control the
behaviour of <module>mod_proxy</module>, an <dfn>environment
variable</dfn> may also control the SCGI protocol
provider:</p>
<dl>
<dt>proxy-scgi-pathinfo</dt>
<dd>By default <module>mod_proxy_scgi</module> will neither create
nor export the <var>PATH_INFO</var> environment variable. This allows
the backend SCGI server to correctly determine <var>SCRIPT_NAME</var>
and <var>Script-URI</var> and be compliant with RFC 3875 section 3.3.
If instead you need <module>mod_proxy_scgi</module> to generate
a "best guess" for <var>PATH_INFO</var>, set this env-var. The
variable must be set before <directive module="mod_env">SetEnv</directive>
is effective. <directive module="mod_setenvif">SetEnvIf</directive> can be
used instead: <code>SetEnvIf Request_URI . proxy-scgi-pathinfo</code>
</dd>
</dl>
</section>
<directivesynopsis>
<name>ProxySCGISendfile</name>
<description>Enable evaluation of <var>X-Sendfile</var> pseudo response
header</description>
<syntax>ProxySCGISendfile On|Off|<var>Headername</var></syntax>
<default>ProxySCGISendfile Off</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context></contextlist>
<usage>
<p>The <directive>ProxySCGISendfile</directive> directive enables the
SCGI backend to let files be served directly by the gateway. This is useful
for performance purposes — httpd can use <code>sendfile</code> or other
optimizations, which are not possible if the file comes over the backend
socket. Additionally, the file contents are not transmitted twice.</p>
<p>The <directive>ProxySCGISendfile</directive> argument determines the
gateway behaviour:</p>
<dl>
<dt><code>Off</code></dt>
<dd>No special handling takes place.</dd>
<dt><code>On</code></dt>
<dd>The gateway looks for a backend response header called
<code>X-Sendfile</code> and interprets the value as the filename to serve.
The header is removed from the final response headers. This is equivalent to
<code>ProxySCGISendfile X-Sendfile</code>.</dd>
<dt>anything else</dt>
<dd>Similar to <code>On</code>, but instead of the hardcoded header name
<code>X-Sendfile</code>, the argument is used as the header name.</dd>
</dl>
<example><title>Example</title>
<highlight language="config">
# Use the default header (X-Sendfile)
ProxySCGISendfile On
# Use a different header
ProxySCGISendfile X-Send-Static
</highlight>
</example>
</usage>
</directivesynopsis>
<directivesynopsis>
<name>ProxySCGIInternalRedirect</name>
<description>Enable or disable internal redirect responses from the
backend</description>
<syntax>ProxySCGIInternalRedirect On|Off|<var>Headername</var></syntax>
<default>ProxySCGIInternalRedirect On</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context></contextlist>
<compatibility>The <var>Headername</var> feature is available in Apache
httpd 2.4.13 and later.</compatibility>
<usage>
<p>The <directive>ProxySCGIInternalRedirect</directive> enables the backend
to internally redirect the gateway to a different URL. This feature
originates in <module>mod_cgi</module>, which internally redirects the
response if the response status is <code>OK</code> (<code>200</code>) and
the response contains a <code>Location</code> (or configured alternate
header) and its value starts with a slash (<code>/</code>). This value is
interpreted as a new local URL that Apache httpd internally redirects to.</p>
<p><module>mod_proxy_scgi</module> does the same as
<module>mod_cgi</module> in this regard, except that you can turn off the
feature or specify the use of a header other than <code>Location</code>.</p>
<example><title>Example</title>
<highlight language="config">
ProxySCGIInternalRedirect Off
# Django and some other frameworks will fully qualify "local URLs"
# set by the application, so an alternate header must be used.
<Location /django-app/>
ProxySCGIInternalRedirect X-Location
</Location>
</highlight>
</example>
</usage>
</directivesynopsis>
</modulesynopsis>
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