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WSGIRewrite

WSGIRewrite is an implementation of a mod_rewrite compatible URL rewriter, consisting of a WSGI middleware implementing an URL rewriter that uses the same syntax as the (in)famous mod_rewrite module for Apache. Most of mod_rewrite features are supported, including redirecting with a specific status code, proxying, conditional rules based on environment variables and chained rules.

The middleware was written to be used with Paste Deploy as filter:

[pipeline:main]
pipeline = wsgirewrite myapp

[filter:wsgirewrite]
use = egg:WSGIRewrite
config = /path/to/htaccess

[app:myapp]
...

Where config specifies a file with the rewriting rules following mod_rewrite's syntax:

RewriteCond  %{HTTP_USER_AGENT}  ^Mozilla.*
RewriteRule  ^/$                 /homepage.max.html  [L]

RewriteCond  %{HTTP_USER_AGENT}  ^Lynx.*
RewriteRule  ^/$                 /homepage.min.html  [L]

RewriteRule  ^/$                 /homepage.std.html  [L]

Optionally, you can also specify rules directly on the INI file using the rulesets variable:

[filter:wsgirewrite]
use = egg:WSGIRewrite
rulesets = feed blocked

[wsgirewrite:feed]
# redirect /atom.xml to real feed location
rule1 = ^/atom.xml$ /index.php?format=Atom1.0

[wsgirewrite:blocked]
# block host1.example.com and host2.example.com
# this could be done by matching ``host(1|2)``; I'm
# using these rules just to demonstrate the ``OR``
# flag functionality.
cond1 = %{REMOTE_HOST} ^host1\.example\.com$ [OR]
cond2 = %{REMOTE_HOST} ^host2\.example\.com$
# no redirection (-), Forbidden
rule1 = ^.*$ - F

In case both config and rulesets are specified, the latter are evaluated first.

Here's an example of instantiating the middleware directly:

>>> app = RewriteMiddleware(some_app, [
...     ([], # conditions (none, in this case)
...      [   # rules
...          ("^/page.html$", "/new_page.html", []),
...      ]
...     )
... ])

This example will redirect requests for /page.html to the URL /new_page.html. Simple as that.

Limitations

RewriteConds:
  • no RewriteMap expansions
  • server variables do not include REQUEST_FILENAME or SCRIPT_FILENAME
  • CondPattern can not test for files, urls or directories
  • %{ENV:variable}, %{SSL:variable}, %{HTTP:header}, %{LA-U:variable}, %{LA-F:variable} not supported
RewriteRules:
  • mapping functions not supported
  • passthrough|PT not implemented (but should work)
  • handler|H not implemented