Apache HTTP Server Version 2.4
Apache Module mod_proxy_express
| Description: | Dynamic mass reverse proxy extension for
mod_proxy |
|---|---|
| Status: | Extension |
| Module Identifier: | proxy_express_module |
| Source File: | mod_proxy_express.c |
Summary
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.
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.
Limitations
- 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 usingmod_rewritewithRewriteMapand 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" </VirtualHost>
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.
Bugfix checklist
See also
ProxyExpressDBMFile Directive
| Description: | Pathname to DBM file. |
|---|---|
| Syntax: | ProxyExpressDBMFile <pathname> |
| Default: | None |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_proxy_express |
| Compatibility: | Available in Apache 2.3.13 and later |
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.
Note
The file is constructed from a plain text file format using
the httxt2dbm
utility.
ProxyExpress map file
##
##express-map.txt:
##
www1.example.com http://192.168.211.2:8080
www2.example.com http://192.168.211.12:8088
www3.example.com http://192.168.212.10
Create DBM file
httxt2dbm -i express-map.txt -o emap
Configuration
ProxyExpressEnable on
ProxyExpressDBMFile emap
ProxyExpressDBMType Directive
| Description: | DBM type of file. |
|---|---|
| Syntax: | ProxyExpressDBMFile <type> |
| Default: | "default" |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_proxy_express |
| Compatibility: | Available in Apache 2.3.13 and later |
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):
| Value | Description |
|---|---|
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: | off |
| Context: | server config, virtual host |
| Status: | Extension |
| Module: | mod_proxy_express |
| Compatibility: | Available in Apache 2.3.13 and later |
The ProxyExpressEnable directive
controls whether the module will be active.