mirror of
https://github.com/wagtail/wagtail.git
synced 2024-11-30 19:20:56 +01:00
122 lines
4.5 KiB
ReStructuredText
122 lines
4.5 KiB
ReStructuredText
.. _frontend_cache_purging:
|
|
|
|
Frontend cache purging
|
|
======================
|
|
|
|
.. versionadded:: 0.4
|
|
|
|
Many websites use a frontend cache such as Varnish, Squid or Cloudflare to gain extra performance. The downside of using a frontend cache though is that they don't respond well to updating content and will often keep an old version of a page cached after it has been updated.
|
|
|
|
This document describes how to configure Wagtail to purge old versions of pages from a frontend cache whenever a page gets updated.
|
|
|
|
|
|
Setting it up
|
|
~~~~~~~~~~~~~
|
|
|
|
Firstly, add ``"wagtail.contrib.wagtailfrontendcache"`` to your INSTALLED_APPS:
|
|
|
|
.. code-block:: python
|
|
|
|
INSTALLED_APPS = [
|
|
...
|
|
|
|
"wagtail.contrib.wagtailfrontendcache"
|
|
]
|
|
|
|
|
|
The ``wagtailfrontendcache`` module provides a set of signal handlers which will automatically purge the cache whenever a page is published or deleted. You should register these somewhere at the top of your ``urls.py`` file:
|
|
|
|
.. code-block:: python
|
|
|
|
# urls.py
|
|
from wagtail.contrib.wagtailfrontendcache.signal_handlers import register_signal_handlers
|
|
|
|
register_signal_handlers()
|
|
|
|
|
|
You then need to set the ``WAGTAILFRONTENDCACHE_LOCATION`` setting to the URL of your Varnish/Squid cache server. This must be a direct connection to the server and cannot go through another proxy. By default, this is set to ``http://127.0.0.1:8000`` which is very likely incorrect.
|
|
|
|
Finally, make sure you have configured your frontend cache to accept PURGE requests:
|
|
|
|
- `Varnish <https://www.varnish-cache.org/docs/3.0/tutorial/purging.html>`_
|
|
- `Squid <http://wiki.squid-cache.org/SquidFaq/OperatingSquid#How_can_I_purge_an_object_from_my_cache.3F>`_
|
|
|
|
|
|
Advanced useage
|
|
~~~~~~~~~~~~~~~
|
|
|
|
Purging more than one URL per page
|
|
----------------------------------
|
|
|
|
By default, Wagtail will only purge one URL per page. If your page has more than one URL to be purged, you will need to override the ``get_cached_paths`` method on your page type.
|
|
|
|
.. code-block:: python
|
|
|
|
class BlogIndexPage(Page):
|
|
def get_blog_items(self):
|
|
# This returns a Django paginator of blog items in this section
|
|
return Paginator(self.get_children().live().type(BlogPage), 10)
|
|
|
|
def get_cached_paths(self):
|
|
# Yield the main URL
|
|
yield '/'
|
|
|
|
# Yield one URL per page in the paginator to make sure all pages are purged
|
|
for page_number in range(1, self.get_blog_items().num_pages):
|
|
yield '/?page=' + str(page_number)
|
|
|
|
|
|
Purging index pages
|
|
-------------------
|
|
|
|
Another problem is pages that list other pages (such as a blog index) will not be purged when a blog entry gets added, changed or deleted. You may want to purge the blog index page so the updates are added into the listing quickly.
|
|
|
|
This can be solved by using the ``purge_page_from_cache`` utility function which can be found in the ``wagtail.contrib.wagtailfrontendcache.utils`` module.
|
|
|
|
Let's take the the above BlogIndexPage as an example. We need to register a signal handler to run when one of the BlogPages get updated/deleted. This signal handler should call the ``purge_page_from_cache`` function on all BlogIndexPages that contain the BlogPage being updated/deleted.
|
|
|
|
|
|
.. code-block:: python
|
|
|
|
# models.py
|
|
from django.db.models.signals import pre_delete
|
|
|
|
from wagtail.wagtailcore.signals import page_published
|
|
from wagtail.contrib.wagtailfrontendcache.utils import purge_page_from_cache
|
|
|
|
|
|
...
|
|
|
|
|
|
def blog_page_changed(blog_page):
|
|
# Find all the live BlogIndexPages that contain this blog_page
|
|
for blog_index in BlogIndexPage.objects.live():
|
|
if blog_page in blog_index.get_blog_items().object_list:
|
|
# Purge this blog index
|
|
purge_page_from_cache(blog_index)
|
|
|
|
|
|
@register(page_published, sender=BlogPage):
|
|
def blog_published_handler(instance):
|
|
blog_page_changed(instance)
|
|
|
|
|
|
@register(pre_delete, sender=BlogPage)
|
|
def blog_deleted_handler(instance):
|
|
blog_page_changed(instance)
|
|
|
|
|
|
Purging individual URLs
|
|
-----------------------
|
|
|
|
``wagtail.contrib.wagtailfrontendcache.utils`` provides another utils function called ``purge_url_from_cache``. As the name suggests, this purges an individual URL from the cache.
|
|
|
|
For example, this could be useful for purging a single page of blogs:
|
|
|
|
.. code-block:: python
|
|
|
|
from wagtail.contrib.wagtailfrontendcache.utils import purge_url_from_cache
|
|
|
|
# Purge the first page of the blog index
|
|
purge_url_from_cache(blog_index.url + '?page=1')
|