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The Apache HTTP Server Reference Manual
by Apache Software Foundation
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ISBN 9781906966034
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3.64  Apache Module mod_proxy_scgi



Description:

SCGI gateway module for mod_proxy

Status:

Extension

Module Identifier:

proxy_scgi_module

Source File:

mod_proxy_scgi.c

Compatibility:

Available in version 2.2.14 and later



Summary

This module requires the service of mod_proxy. It provides support for the SCGI protocol, version 153 .

Thus, in order to get the ability of handling the SCGI protocol, mod_proxy and mod_proxy_scgi have to be present in the server.

Warning Do not enable proxying until you have secured your server (p. 729). Open proxy servers are dangerous both to your network and to the Internet at large.

Directives:

ProxySCGIInternalRedirect

ProxySCGISendfile

See also:

3.64.1  Examples

Remember, in order to make the following examples work, you have to enable mod_proxy and mod_proxy_scgi.

Simple gateway

ProxyPass /scgi-bin/ scgi://localhost:4000/

The balanced gateway needs mod_proxy_balancer in addition to the already mentioned proxy modules.

Balanced gateway

ProxyPass /scgi-bin/ balancer://somecluster/
<Proxy balancer://somecluster/>

BalancerMember scgi://localhost:4000/
BalancerMember scgi://localhost:4001/

</Proxy>

ProxySCGIInternalRedirect Directive

Description:

Enable or disable internal redirect responses from the backend

Syntax:

ProxySCGIInternalRedirect On|Off

Default:

ProxySCGIInternalRedirect On

Context:

server config, virtual host, directory

Status:

Extension

Module:

mod_proxy_scgi

The ProxySCGIInternalRedirect enables the backend to internally redirect the gateway to a different URL. This feature origins in mod_cgi, which internally redirects the response, if the response status is OK (200) and the response contains a Location header and its value starts with a slash (/). This value is interpreted as a new local URL that Apache internally redirects to.

mod_proxy_scgi does the same as mod_cgi in this regard, except that you can turn off the feature.

Example

ProxySCGIInternalRedirect Off

ProxySCGISendfile Directive

Description:

Enable evaluation of X-Sendfile pseudo response header

Syntax:

ProxySCGISendfile On|Off|Headername

Default:

ProxySCGISendfile Off

Context:

server config, virtual host, directory

Status:

Extension

Module:

mod_proxy_scgi

The ProxySCGISendfile directive enables the SCGI backend to let files serve directly by the gateway. This is useful performance purposes – the httpd can use sendfile or other optimizations, which are not possible if the file comes over the backend socket.

The ProxySCGISendfile argument determines the gateway behaviour:

Off
No special handling takes place.
On
The gateway looks for a backend response header called X-Sendfile and interprets the value as filename to serve. The header is removed from the final response headers. This is equivalent to ProxySCGIRequest X-Sendfile.
anything else
Similar to On, but instead of the hardcoded header name the argument is applied as header name.

Example

# Use the default header (X-Sendfile)
ProxySCGISendfile On
# Use a different header
ProxySCGISendfile X-Send-Static

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