# Apache module mod_proxy

This module is contained in the `mod_proxy.c` file, and is not compiled in by default. It provides for a caching proxy server. It is only available in Apache 1.1 and later.

### Note:

This module is experimental. Use at your own risk.

## Summary

This module implements a proxy/cache for Apache. It implements proxying capability for `FTP`, `HTTP/0.9`, and `HTTP/1.0`. The module can be configured to connect to other proxy modules for these and other protocols.

## Directives

- ProxyRequests
- ProxyRemote
- ProxyPass
- CacheRoot
- CacheSize
- CacheGcInterval
- CacheMaxExpire
- CacheLastModifiedFactor
- CacheDefaultExpire
- NoCache

## ProxyRequests

Syntax: ProxyRequests on/off
Default: `ProxyRequests Off`
Context: server config
Status: Base
Module: mod_proxy
Compatibility: ProxyRequest is only available in Apache 1.1 and later.

This allows or prevents Apache from functioning as a proxy server. Setting ProxyRequests to 'off' does not disable use of the ProxyPass directive.

## ProxyRemote

Syntax: ProxyRemote <match> <remote-server>
Context: server config
Status: Base
Module: mod_proxy
Compatibility: ProxyRemote is only available in Apache 1.1 and later.

This defines remote proxies to this proxy. <match> is either the name of a URL-scheme that the remote server supports, or a partial URL for which the remote server should be used, or '$' to indicate the server should be contacted for all requests. <remote-server> is a partial URL for the remote server. Syntax:

      <remote-server> = <protocol>://<hostname>[:port]

<protocol> is the protocol that should be used to communicate with the remote server; only "http" is supported by this module. Example:

      ProxyRemote ftp http://ftpproxy.mydomain.com:8080
      ProxyRemote http://goodguys.com/ http://mirrorguys.com:8000
      ProxyRemote * http://cleversite.com

## ProxyPass

Syntax: ProxyPass <path> <url>
Context: server config
Status: Base
Module: mod_proxy
Compatibility: ProxyPass is only available in Apache 1.1 and later.

This directive allows remote servers to be mapped into the space of the local server; the local server does not act as a proxy in the conventional sense, but appears to be a mirror of the remote server. <path> is the name of a local virtual path; <url> is a partial URL for the remote server. Suppose the local server has address http://wibble.org; then

       ProxyPass /mirror/foo http://foo.com

Will cause a local request for the http://wibble.org/mirror/foo/bar to be internally converted into a proxy request to http://foo.com/bar

## CacheRoot

Syntax: CacheRoot <directory>
Context: server config
Status: Base
Module: mod_proxy
Compatibility: CacheRoot is only available in Apache 1.1 and later.

Sets the name of the directory to contain cache files; this must be writable by the httpd server.

## CacheSize

Syntax: CacheSize <size>
Default: `CacheSize 5`
Context: server config
Status: Base
Module: mod_proxy
Compatibility: CacheSize is only available in Apache 1.1 and later.

Sets the desired space usage of the cache, in Kb (1024 byte units). Although usage may grow above this setting, the garbage collection will delete files until the usage is at or below this setting.

## CacheGcInterval

Syntax: CacheGcInterval <time>
Context: server config
Status: Base
Module: mod_proxy
Compatibility: CacheGcinterval is only available in Apache 1.1 and later.

Check the cache every <time> hours, and delete files if the space usage is greater than that set by CacheSize.

## CacheMaxExpire

Syntax: CacheMaxExpire <time>
Default: CacheMaxExpire 24
Context: server config
Status: Base
Module: mod_proxy
Compatibility: CacheMaxExpire is only available in Apache 1.1 and later.

Cachable HTTP documents will be retained for at most <time> hours without checking the origin server. Thus documents can be at most <time> hours out of date. This restriction is enforced even if an expiry date was supplied with the document.

## CacheLastModifiedFactor

Syntax: CacheLastModifiedFactor <factor>
Default: CacheLastModifiedFactor 0.1
Context: server config
Status: Base
Module: mod_proxy
Compatibility: CacheLastModified is only available in Apache 1.1 and later.

If the origin HTTP server did not supply an expiry date for the document, then estimate on using the formula

      expiry-period = time-since-last-modification * <factor>

For example, if the document was last modified 10 hours ago, and <factor> is 0.1, then the expiry period wil be set to 10*0.1 = 1 hour.

If the expiry-period would be longer than that set by CacheMaxExpire, then the latter takes precedence.

## CacheDefaultExpire

Syntax: CacheDefaultExpire <time>
Default: CacheDefaultExpire 1
Context: server config
Status: Base
Module: mod_proxy
Compatibility: CacheDefaultExpire is only available in Apache 1.1 and later.

If the document is fetched via a protocol that does not support expirytimes, then use <time> as the expiry time. CacheMaxExpire does not override.

## NoCache

Syntax: NoCache <host/domain list>
Context: server config
Status: Base
Module: mod_proxy
Compatibility: NoCache is only available in Apache 1.1 and later.

The NoCache directive specifies a list of hosts and/or domains, separated by spaces. HTTP documents from hosts or domains in the list are not cached by the proxy server. Example:

      NoCache joes.garage.com some.host.co.uk wotsamattau.edu