Version 4.3.0¶
Version 4.3.0 of mod_wsgi can be obtained from:
Known Issues¶
1. The makefiles for building mod_wsgi on Windows are currently broken and need updating. As most new changes relate to mod_wsgi daemon mode, which is not supported under Windows, you should keep using the last available binary for version 3.X on Windows instead.
Bugs Fixed¶
1. Performing authorization using the WSGIAuthGroupScript was not
working correctly on Apache 2.4 due to changes in how auth providers
and authentication/authorization works. The result could be that a user
could gain access to a resource even though they were not in the
required group.
2. Under Apache 2.4, when creating the environ dictionary for
passing into access/authentication/authorisation handlers, the behvaiour
of Apache 2.4 as it pertained to the WSGI application, whereby it
blocked the passing of any HTTP headers with a name which did not contain
just alphanumerics or ‘-‘, was not being mirrored. This created the
possibility of HTTP header spoofing in certain circumstances. Such headers
are now being ignored.
3. When home option was used with WSGIDaemonProcess directive an
empty string was added to sys.path. This meant current working directory
would be searched. This was fine so long as the current working directory
wasn’t changed, but if it was, it would no longer look in the home
directory. Need to use the actual home directory instead.
4. Fixed Django management command integration so would work for versions
of Django prior to 1.6 where BASE_DIR didn’t exist in Django settings
module.
Features Changed¶
1. In Apache 2.4, any headers with a name which does not include only
alphanumerics or ‘-‘ are blocked from being passed into a WSGI application
when the CGI like WSGI environ dictionary is created. This is a
mechanism to prevent header spoofing when there are multiple headers where
the only difference is the use of non alphanumerics in a specific character
position.
This protection mechanism from Apache 2.4 is now being restrospectively applied even when Apache 2.2 is being used and even though Apache itself doesn’t do it. This may technically result in headers that were previously being passed, no longer being passed. The change is also technically against what the HTTP RFC says is allowed for HTTP header names, but such blocking would occur in Apache 2.4 anyway due to changes in Apache. It is also understood that other web servers such as nginx also perform the same type of blocking. Reliance on HTTP headers which use characters other than alphanumerics and ‘-‘ is therefore dubious as many servers will now discard them when needing to be passed into a system which requires the headers to be passed as CGI like variables such as is the case for WSGI.
2. In Apache 2.4, only wsgi-group is allowed when using the Require
directive for group authorisation. In prior Apache versions group would
also be accepted and matched by the wsgi auth provider. The inability
to use group is due to a change in Apache itself and not mod_wsgi. To
avoid any issues going forward though, the mod_wsgi code will now no longer
check for group even if for some reason Apache still decides to pass
the authorisation check off to mod_wsgi even when it shouldn’t.
New Features¶
1. The value of the REMOTE_USER variable for an authenticated user
when user Basic authentication can now be overridden from an
authentication handler specified using the WSGIAuthUserScript. To
override the name used to identify the user, instead of returning True
when indicating that the user is allowed, return the name to be used for
that user as a string. That value will then be passed through in
REMOTE_USER in place of any original value:
def check_password(environ, user, password):
if user == 'spy':
if password == 'secret':
return 'grumpy'
return False
return None
2. Added the --debug-mode option to mod_wsgi-express which results
in Apache and the WSGI application being run in a single process which is
left attached to stdin/stdout of the shell where the script was run. Only a
single thread will be used to handle any requests.
This feature enables the ability to interactively debug a Python WSGI
application using the Python debugger (pdb). The simplest way to
break into the Python debugger is by adding to your WSGI application code:
import pdb; pdb.set_trace()
3. Added the --application-type option to mod_wsgi-express. This
defaults to script indicating that the target WSGI application provided
to mod_wsgi-express is a WSGI script file defined by a relative or
absolute file system path.
In addition to script, it is also possible to supply for the application
type module and paste.
For the case of module, the target WSGI application will be taken to
reside in a Python module with the specified name. This module will be
loaded using the standard Python module import system and so must reside
on the Python module search path.
For the case of paste, the target WSGI application will be taken to be
a Paste deployment configuration file. In loading the Paste deployment
configuration file, any WSGI application pipeline specified by the
configuration will be constructed and the resulting top level WSGI
application entry point returned used as the WSGI application.
Note that the code file for the WSGI script file, Python module, or Paste deployment configuration file, if modified, will all result in the WSGI application being automatically reloaded on the next web request.
4. Added the --auth-user-script and --auth-type options to
mod_wsgi-express to enable the hosted site to implement user
authentication using either HTTP Basic or Digest authentication
mechanisms. The check_password() or get_realm_hash() functions
should follow the same form as if using the WSGIAuthUserScript direct
with mod_wsgi when using manual configuration.
5. Added the --auth-group-script and --auth-group options to
mod_wsgi-express to enable group authorization to be performed using a
group authorization script, in conjunction with a user authentication
script. The groups_for_user() function should follow the same form as
if using the WSGIAuthGroupScript direct with mod_wsgi when using manual
configuration.
By default any users must be a member of the wsgi group. The name of
this group though can be overridden using the --auth-group option.
It is recommended that this be overridden rather than changing your own
application to use the wsgi group.
6. Added the --directory-index option to mod_wsgi-express to enable
a index resource to be added to the document root directory which would
take precedence over the WSGI application for the root page for the site.
7. Added the --with-php5 option to mod_wsgi-express to enable the
concurrent hosting of a PHP web application in conjunction with the WSGI
application. Due to the limitations of PHP, this is currently only
supported if using prefork MPM.
8. Added the --server-name option to mod_wsgi-express. When this is
used and set to the host name for the web site, a virtual host will be
created to ensure that the server only accepts web requests for that host
name.
If the host name starts with www. then web requests will also be
accepted against the parent domain, that is the host name without the
www., but those requests will be automatically redirected to the
specified host name on the same port as that used for the original request.
When the --server-name option is being used, the --server-alias
option can also be specified, multiple times if need be, to setup alternate
names for the web site on which web requests should also be accepted.
Wildcard aliases may be used in the name if wishing to match multiple
sub domains in one go.
If for some reason you do still need to be able to access the server via
localhost when a virtual host for a set server name is being used, you
can supply the --allow-localhost option.
9. Added the --rotate-logs option to mod_wsgi-express to enable log
file rotation. By default the error log and access log, if enabled, will be
rotated when they reach 5MB in size. To change the size at which the log
files will be rotated, use the --max-log-size option. If the
rotatelogs command is not being found properly, its location can be
specified using the --rotatelogs-executable option.
10. Added the --ssl-port and --ssl-certificate options to
mod_wsgi-express. When both are set, with the latter being the stub
path for the SSL certificate .crt and .key file, then HTTPS
requests will be handled over the designated SSL port.
When --https-only is supplied, any requests made over HTTP to the non
SSL port will be automatically redirected so as to use a HTTPS connection
over the SSL connection.
Note that if using the --allow-localhost option, redirection from a
HTTP to HTTPS connection will not occur when access via localhost.
11. Added the --setenv option to mod_wsgi-express to enable request
specific name/value pairs to be added to the WSGI environ dictionary. The
values are restricted to string values.
Also added a companion --passenv option to mod_wsgi-express to
indicate the names of normal process environment variables which should
be added to the per request WSGI environ dictionary.
12. Added the WSGIMapHEADToGET directive for overriding the previous
behaviour of automatically mapping any HEAD request to a GET request
when an Apache output filter was registered that may want to see the complete
response in order to generate correct response headers.
The directive can be set to be either Auto (the default), On which
will always map a HEAD to GET even if no output filters detected and
Off to always preserve the original request method type.
The original behaviour was to avoid problems with users trying to optimise
for HEAD requests and then breaking caching mechanisms because the
response headers for a HEAD request for a resource didn’t match a GET
request against the same resource as required by HTTP.
If using mod_wsgi-express, the --map-head-to-get option can be used with
the same values.
12. Added the --compress-responses option to mod_wsgi-express to
enable compression of common text based responses such as plain text, HTML,
XML, CSS and Javascript.