mkoistinen/sisu-cache-tools

Cache tools for django-cms projects

sisu-cache-tools

Basic cache management tools for djangoCMS projects.

Implements a relatively automatic cache-invalidation capability and a 'precache' management command.

This is useful for sites that have largely static content and are using memcached.

Installation

pip install sisu-cache-tools

Then, add cache_tools to your project's INSTALLED_APPS in settings. Sisu Cache Tools does not use an database models, so no migration is necessary, but it must be added to INSTALLED_APPS, or the management commands will not be found and the signal handlers will not "see" any signals.

Automated Cache invalidation

To get the automated cache-invalidation, add 'taints_cache = True' as a class- attribute on any models that contain objects that will change the way pages appear. Using signals, this module will detect changes to those model objects and invalidate the (entire) cache.

The cache can also be cleared with:

python manage.py clearcache

Automated Varnish Cache Invalidation (via BAN)

New from version 0.1.0

Assuming there are one or more Varnish cache servers with a VCL that includes something like:

acl purge {
    "appserver1.your_domain.xyz",
    "appserver2.your_domain.xyz",
    "appserver3.your_domain.xyz",
}

sub vcl_recv {

	...

    if (req.request == "DELETE" && req.http.X-Ban-Host) {
        if ( !client.ip ~purge ) {
            error 405 "Not allowed";
        }
        ban("obj.http.x-host ~ " + req.http.X-Ban-Host);
        error 200 "Banned";
    }

	...
}

and you have configured a list of these servers in settings.CACHE_SERVERS:

CACHE_SERVERS = [
	10.0.0.1,
	10.0.0.2,
]

and you have django.contrib.sites in use in your settings:

INSTALLED_APPS = (
    ....
    'django.contrib.sites',
    ....
)

...

SITE_ID = 1

Sisu Cache Tools will then send a DELETE request with the header X-Ban-Host to your Varnish cache servers so that even your remote caches are "cleared" too.

Pre-emptive Caching

When the operator is done with all of their changes, the might consider using:

python manage.py precache

to make HTTP requests to every page found in the sitemaps defined in the ROOT_URLCONF. This will essentially preemptively load the pages into the cache so your visitors will get speedy access, even if they're the first one to 'hit' a given page.

Also, to simply review all of the URLs, the operator can use:

python manage.py listurls

And it will print all of the known URLs to stdout.