Apache Module mod_proxy_scgi
Description: | SCGI gateway module for mod_proxy
|
---|---|
Status: | Extension |
ModuleIdentifier: | proxy_scgi_module |
SourceFile: | 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 1.
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. Open proxy servers are dangerous both to your network and to the Internet at large.
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
and at least one load balancer algorithm module, such as mod_lbmethod_byrequests
, in addition to the proxy modules listed above. mod_lbmethod_byrequests
is the default, and will be used for this example configuration.
Balanced gateway
ProxyPass "/scgi-bin/" "balancer://somecluster/" <Proxy "balancer://somecluster"> BalancerMember "scgi://localhost:4000" BalancerMember "scgi://localhost:4001" </Proxy>
Environment Variables
In addition to the configuration directives that control the behaviour of mod_proxy
, an environment variable may also control the SCGI protocol provider:
- proxy-scgi-pathinfo
- By default
mod_proxy_scgi
will neither create nor export the PATH_INFO environment variable. This allows the backend SCGI server to correctly determine SCRIPT_NAME and Script-URI and be compliant with RFC 3875 section 3.3. If instead you needmod_proxy_scgi
to generate a "best guess" for PATH_INFO, set this env-var. The variable must be set beforeSetEnv
is effective.SetEnvIf
can be used instead:SetEnvIf Request_URI . proxy-scgi-pathinfo
ProxySCGIInternalRedirect Directive
Description: | Enable or disable internal redirect responses from the backend |
---|---|
Syntax: | ProxySCGIInternalRedirect On|Off|Headername |
Default: | ProxySCGIInternalRedirect On |
Context: | server config, virtual host, directory |
Status: | Extension |
Module: | mod_proxy_scgi |
Compatibility: | The Headername feature is available in version 2.4.13 and later |
The ProxySCGIInternalRedirect
enables the backend to internally redirect the gateway to a different URL. This feature originates in mod_cgi
, which internally redirects the response if the response status is OK
(200
) and the response contains a Location
(or configured alternate header) and its value starts with a slash (/
). This value is interpreted as a new local URL that Apache httpd internally redirects to.
mod_proxy_scgi
does the same as mod_cgi
in this regard, except that you can turn off the feature or specify the use of a header other than Location
.
Example
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>
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 be served directly by the gateway. This is useful for performance purposes — httpd can use sendfile
or other optimizations, which are not possible if the file comes over the backend socket. Additionally, the file contents are not transmitted twice.
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 the filename to serve. The header is removed from the final response headers. This is equivalent toProxySCGISendfile X-Sendfile
. - anything else
- Similar to
On
, but instead of the hardcoded header nameX-Sendfile
, the argument is used as the header name.
Example
# Use the default header (X-Sendfile) ProxySCGISendfile On # Use a different header ProxySCGISendfile X-Send-Static
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