kopia lustrzana https://github.com/wagtail/wagtail
103 wiersze
3.9 KiB
ReStructuredText
103 wiersze
3.9 KiB
ReStructuredText
Frontend cache purging
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======================
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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.
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This document describes how to configure Wagtail to purge old versions of pages from a frontend cache whenever a page gets updated.
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Setting it up
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~~~~~~~~~~~~~
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Firstly, add ``"wagtail.contrib.wagtailfrontendcache"`` to your INSTALLED_APPS:
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.. code-block:: python
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INSTALLED_APPS = [
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...
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"wagtail.contrib.wagtailfrontendcache"
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]
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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:
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.. code-block:: python
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# urls.py
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from wagtail.contrib.wagtailfrontendcache.signal_handlers import register_signal_handlers
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register_signal_handlers()
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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.
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Finally, make sure you have configured your frontend cache to accept PURGE requests:
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- `Varnish <https://www.varnish-cache.org/docs/3.0/tutorial/purging.html>`_
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- `Squid <http://wiki.squid-cache.org/SquidFaq/OperatingSquid#How_can_I_purge_an_object_from_my_cache.3F>`_
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Advanced useage
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~~~~~~~~~~~~~~~
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Purging more than one URL per page
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----------------------------------
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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.
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.. code-block:: python
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class BlogIndexPage(Page):
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def get_blog_items(self):
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# This returns a Django paginator of blog items in this section
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return Paginator(self.get_children().live().type(BlogPage), 10)
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def get_cached_paths(self):
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# Yield the main URL
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yield '/'
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# Yield one URL per page in the paginator to make sure all pages are purged
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for page_number in range(1, self.get_blog_items().num_pages):
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yield '/?page=' + str(page_number)
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Purging index pages
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-------------------
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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.
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This can be solved by using the ``purge_page_from_cache`` utility function which can be found in the ``wagtail.contrib.wagtailfrontendcache.utils`` module.
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Lets 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.
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.. code-block:: python
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# models.py
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from django.db.models.signals import pre_delete
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from wagtail.wagtailcore.signals import page_published
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from wagtail.contrib.wagtailfrontendcache.utils import purge_page_from_cache
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...
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def blog_page_changed(blog_page):
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# Find all the live BlogIndexPages that contain this blog_page
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for blog_index in BlogIndexPage.objects.live():
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if blog_page in blog_index.get_blog_items().object_list:
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# Purge this blog index
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purge_page_from_cache(blog_index)
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@register(page_published, sender=BlogPage):
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def blog_published_handler(instance):
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blog_page_changed(instance)
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@register(pre_delete, sender=BlogPage)
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def blog_deleted_handler(instance):
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blog_page_changed(instance)
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