django-hosts¶

This Django app routes requests for specific hosts to different URL schemes defined in modules called “hostconfs”.

For example, if you own example.com but want to serve specific content at api.example.com and beta.example.com, add the following to a hosts.py file:

from django_hosts import patterns, host

host_patterns = patterns('path.to',
    host(r'api', 'api.urls', name='api'),
    host(r'beta', 'beta.urls', name='beta'),
)

This causes requests to {api,beta}.example.com to be routed to their corresponding URLconf. You can use your urls.py as a template for these hostconfs.

Patterns are evaluated in order. If no pattern matches, the request is processed in the usual way, ie. using the standard ROOT_URLCONF.

The patterns on the left-hand side are regular expressions. For example, the following ROOT_HOSTCONF setting will route foo.example.com and bar.example.com to the same URLconf.

from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'(foo|bar)', 'path.to.urls', name='foo-or-bar'),
)

Installation¶

First, install the app with your favorite package manager, e.g.:

pip install django-hosts

Alternatively, use the repository on Github.

You can find the full docs here: django-hosts.rtfd.org

Then configure your Django site to use the app:

Add 'django_hosts' to your INSTALLED_APPS setting.
Add 'django_hosts.middleware.HostsMiddleware' to your MIDDLEWARE_CLASSES setting.
Create a module containing your default host patterns, e.g. in the hosts.py file next to your urls.py.
Set the ROOT_HOSTCONF setting to the dotted Python import path of the module containing your host patterns, e.g.:
```
ROOT_HOSTCONF = 'mysite.hosts'
```
Set the DEFAULT_HOST setting to the name of the host pattern you want to refer to as the default pattern. It’ll be used if no other pattern matches or you don’t give a name to the host_url template tag.

Usage¶

Patterns being regular expressions allows setups to feature dynamic (or “wildcard”) host schemes:

from django.conf import settings
from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'www', settings.ROOT_URLCONF, name='www'),
    host(r'(\w+)', 'path.to.custom_urls', name='wildcard'),
)

Here, requests to www.example.com will be routed as normal but a request to admin.example.com is routed to path.to.custom_urls.

As patterns are matched in order, we placed www first as it otherwise would have matched against \w+ and thus routed to the wrong destination.

Alternatively, we could have used negative lookahead, given the value of the ROOT_URLCONF setting:

from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'(?!www)\w+', 'path.to.custom_urls', name='wildcard'),
)

Settings¶

django.conf.settings.ROOT_HOSTCONF(required)¶: The dotted Python import path of the module containing your host patterns. Similar to ROOT_URLCONF.

django.conf.settings.DEFAULT_HOST(required)¶: The name of the host pattern you want to refer to as the default pattern. Used if no other host pattern matches or no host name is passed to the host_url() template tag.

django.conf.settings.PARENT_HOST(optional)¶: The parent domain name to be appended to the reversed domain (e.g. using the host_url() template tag).

django.conf.settings.HOST_SITE_TIMEOUT(optional)¶: The time to cache the host in the default cache backend, in seconds, when using the cached_host_site() callback. Defaults to 3600.

django.conf.settings.HOST_SCHEME(optional)¶: The scheme to prepend host names with during reversing, e.g. when using the host_url() template tag. Defaults to //.

Contents¶

Per-host callbacks¶

Parsing the host from request.get_host() and lookup its corresponding object instance (e.g. site) in every view violates DRY. If these dynamic hosts had a lot of views this would become particularly unwieldy.

To remedy this, you can optionally specify a callback method to be called if your host matches.

Simply define a callback function:

from django.shortcuts import get_object_or_404
from django.contrib.auth.models import User

def custom_fn(request, username):
    request.viewing_user = get_object_or_404(User, username=username)

..and pass it as the callback paramter to the host object:

from django.conf import settings
from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'www', settings.ROOT_URLCONF, name='www'),
    host(r'(?P<username>\w+)', 'path.to.custom_urls',
         callback='path.to.custom_fn', name='with-callback'),
)

This example avoids the duplicated work in every view by attaching a viewing_user instance to the request object. Views referenced by the “dynamic” URLconf can now assume that this object exists.

The custom method is called with the request object and any named captured arguments, similar to regular Django url processing.

Callbacks may return either None or an HttpResponse object.

If it returns None, the request continues to be processed and the appropriate view is eventually called.
If a callback returns an HttpResponse object, that HttpResponse is returned to the client without any further processing.

Note

There are a few things to keep in mind when using the callbacks:

Callbacks are executed with the URLconf set to the second argument in the host_patterns list. For example, in the example above, the callback will be executed with the URLconf as path.to.custom_urls and not the default URLconf.
This can cause problems when reversing URLs within your callback as they may not be “visible” to django.core.urlresolvers.reverse() as they are specified in (eg.) the default URLconf.
To remedy this, specify the urlconf parameter when calling reverse().
When using dynamic hosts based on user input, ensure users cannot specify names that conflict with static subdomains such as “www” or their subdomain will not be accessible.
Don’t forget to add handler404 and handler500 entries for your custom URLconfs.

Included callbacks¶

django-hosts includes the following callbacks:

Template tags¶

django_hosts.templatetags.hosts.host_url(view_name, [view_args, view_kwargs, ]host_name[, host_args, host_kwargs, as_var])¶

Now if you want to actually refer to the full URLs in your templates you can use the included host_url template tag. So imagine having a host pattern of:

from django.conf import settings
from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'admin', settings.ROOT_URLCONF, name='our-admin'),
)

and a ROOT_URLCONF of:

from django.conf.urls.defaults import patterns, url

urlpatterns = patterns('mysite.admin',
    url(r'^dashboard/$', 'dashboard', name='dashboard'),
)

then this example will create a link to the admin dashboard:

{% load hosts %}

<a href="{% host_url dashboard on our-admin %}">Admin dashboard</a>

which will be rendered as:

<a href="//admin/dashboard/">Admin dashboard</a>

Note

The double slash at the beginning of the href is an easy way to not have to worry about which scheme (http or https) is used. Your browser will automatically choose the currently used scheme. If you’re on https://mysite.com/ a link with an href of //mysite.com/about/ would actually point to https://mysite.com/about/.

For more information see the The protocol-relative URL article by Paul Irish or the appropriate section in RFC 3986.

Changed in version 0.5.

You can override the used scheme with the HOST_SCHEME setting.

Setting a context variable¶

New in version 0.4.0.

If you’d like to retrieve a URL without displaying it, you can save the result of the template tag in a template variable and use it later on, e.g.:

{% load hosts %}

{% host_url homepage as homepage_url %}
<a href="{{ homepage_url }}" title="Go back to {{ homepage_url }}">Home</a>

Fully qualified domain names (FQDN)¶

In case you want to append a default domain name to the domain part of the rendered URL you can simply set the PARENT_HOST, e.g:

PARENT_HOST = 'example.com'

This would render the link of the previous section as:

<a href="//admin.example.com/dashboard/">Admin dashboard</a>

Alternatively – in case you don’t want to append this parent domain to all URLs you can also spell out the domain in the host pattern:

from django.conf import settings
from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'admin\.example\.com', settings.ROOT_URLCONF, name='admin'),
)

Host and URL parameters¶

If your host pattern contains an parameter (or keyed parameter), like:

from django.conf import settings
from django_hosts import patterns, host

host_patterns = patterns('',
    host(r'www', settings.ROOT_URLCONF, name='homepage'),
    host(r'(\w+)', 'path.to.support_urls', name='wildcard'),
    host(r'(?P<username>\w+).users', 'path.to.user_urls', name='user-area'),
)

you can also easily pass parameters to the host_url() template tag:

{% load hosts %}

<a href="{% host_url user-dashboard on user-area username='johndoe' %}">John's dashboard</a>
<a href="{% host_url faq-index on wildcard 'help' %}">FAQ</a>

Which will be rendered (with a PARENT_HOST of 'example.com') as:

<a href="//johndoe.users.example.com/">John's dashboard</a>
<a href="//help.example.com/faq/">FAQ</a>

Reference¶

`hosts` and `patterns`¶

Reversal with `reverse_host` and `reverse_full`¶

`HostSiteManager` model manager¶

Changelog¶

0.5 (2012/08/29)¶

Fixed host reversing when the PARENT_HOST equals
Added HOST_SCHEME setting to be able to override the default URL scheme when reversing hosts.

0.4.2 (2012/02/14)¶

Removed a unneeded installation time requirement for Django <= 1.4.
Removed the use of versiontools due to unwanted installation time side effects.
Refactored tests slightly.

0.4.1 (2011/12/23)¶

Added cached_host_site() callback which stores the matching Site instance in the default cache backend (also see new HOST_SITE_TIMEOUT setting).
Throw warning if django-debug-toolbar is used together with the django_hosts and the order of the MIDDLEWARE_CLASSES setting isn’t correct.
Added CI server at https://ci.enn.io/job/django-hosts/

0.4 (2011/11/04)¶

Added ability to save the result of host_url() template tag in a template context variable.

0.3 (2011/09/30)¶

Consolidated reversal internals.
Removed unfinished support for the Django Debug Toolbar.
Added a custom callback which uses Django’s sites app to retrieve a Site instance matching the current host, setting request.site.
Extended tests dramatically (100% coverage).
Added docs at http://django-hosts.rtfd.org
Stopped preventing the name ‘default’ for hosts.

0.2.1 (2011/05/31)¶

Fixed issue related to the PARENT_HOST setting when used with empty host patterns.
Stopped automatically emulating hosts in debug mode.

0.2 (2011/05/31)¶

BACKWARDS INCOMPATIBLE Renamed the package to django_hosts

Please change your import from:
```
from hosts import patterns, hosts
```
to:
```
from django_hosts import patterns, hosts
```
BACKWARDS INCOMPATIBLE Changed the data type that the django_hosts.patterns function returns to be a list instead of a SortedDict to follow conventions of Django’s URL patterns. You can use that for easy extension of the patterns, e.g.:
```
from django_hosts import patterns, host
from mytemplateproject.hosts import host_patterns

host_patterns += patterns('',
    host('www2', 'mysite.urls.www2', name='www2')
)
```
Extended tests to have full coverage.
Fixed prefix handling.

0.1.1 (2011/05/30)¶

Fixed docs issues.
Use absolute imports where possible.

0.1 (2011/05/29)¶

Initial release with middleware, reverse and templatetags.

FAQ¶

Issues¶

For any bug reports and feature requests, please use the Github issue tracker.

Thanks¶

Many thanks to the folks at playfire for releasing their django-dynamic-subdomains app, which was the inspiration for this app.