mod_proxy_scgi
SCGI gateway module for mod_proxy
Extension
mod_proxy_scgi.c
proxy_scgi_module
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.
mod_proxy
mod_proxy_balancer
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 need mod_proxy_scgi to generate
a "best guess" for PATH_INFO, set this env-var. The
variable must be set before SetEnv
is effective. SetEnvIf can be
used instead:
SetEnvIf Request_URI . proxy-scgi-pathinfo
ProxySCGISendfile
Enable evaluation of X-Sendfile pseudo response
header
ProxySCGISendfile On|Off|Headername
ProxySCGISendfile Off
server configvirtual host
directory
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 to
ProxySCGISendfile X-Sendfile.
- anything else
- Similar to
On, but instead of the hardcoded header name
X-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
ProxySCGIInternalRedirect
Enable or disable internal redirect responses from the
backend
ProxySCGIInternalRedirect On|Off|Headername
ProxySCGIInternalRedirect On
server configvirtual host
directory
The Headername feature is available in Apache
httpd 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>