Apache > HTTP Server > Documentation > Version 2.4 > Modules

Apache Module mod_proxy_express

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Description:Dynamic mass reverse proxy extension for mod_proxy
Module Identifier:proxy_express_module
Source File:mod_proxy_express.c
Compatibility:Available in Apache 2.3.13 and later


This module creates dynamically configured mass reverse proxies, by mapping the Host: header of the HTTP request to a server name and backend URL stored in a DBM file. This allows for easy use of a huge number of reverse proxies with no configuration changes. It is much less feature-full than mod_proxy_balancer, which also provides dynamic growth, but is intended to handle much, much larger numbers of backends. It is ideally suited as a front-end HTTP switch and for micro-services architectures.

This module requires the service of mod_proxy.


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.


  • This module is not intended to replace the dynamic capability of mod_proxy_balancer. Instead, it is intended to be mostly a lightweight and fast alternative to using mod_rewrite with RewriteMap and the [P] flag for mapped reverse proxying.
  • It does not support regex or pattern matching at all.
  • It emulates:
    <VirtualHost *:80>
       ServerName front.end.server
       ProxyPass        "/" "back.end.server:port"
       ProxyPassReverse "/" "back.end.server:port"
    That is, the entire URL is appended to the mapped backend URL. This is in keeping with the intent of being a simple but fast reverse proxy switch.
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See also


ProxyExpressDBMFile Directive

Description:Pathname to DBM file.
Syntax:ProxyExpressDBMFile pathname
Context:server config, virtual host

The ProxyExpressDBMFile directive points to the location of the Express map DBM file. This file serves to map the incoming server name, obtained from the Host: header, to a backend URL.


The file is constructed from a plain text file format using the httxt2dbm utility.

ProxyExpress map file



Create DBM file

httxt2dbm -i express-map.txt -o emap


ProxyExpressEnable on
ProxyExpressDBMFile emap

ProxyExpressDBMType Directive

Description:DBM type of file.
Syntax:ProxyExpressDBMType type
Default:ProxyExpressDBMType default
Context:server config, virtual host

The ProxyExpressDBMType directive controls the DBM type expected by the module. The default is the default DBM type created with httxt2dbm.

Possible values are (not all may be available at run time):

db Berkeley DB files
gdbm GDBM files
ndbm NDBM files
sdbm SDBM files (always available)
default default DBM type

ProxyExpressEnable Directive

Description:Enable the module functionality.
Syntax:ProxyExpressEnable on|off
Default:ProxyExpressEnable off
Context:server config, virtual host

The ProxyExpressEnable directive controls whether the module will be active.

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