roan 0.1

Django per-model cache purging

Roan is a per-model url purging Django app. It connects to model signals and purge URLs wherever a model is saved, updated or deleted.

Getting started

Installation

You can install Roan using pip:

$ [sudo] pip install roan

The only dependency is requests, that will be installed automatically by pip (if you don’t use the --no-deps argument).

Configuration

Roan uses only an optional setting: ROAN_PURGE_URL. If you don’t specify it, it’ll be http://localhost/purge.

Example of configuration:

ROAN_PURGE_URL = 'http://nginx.souza.cc/clean'

nginx proxy_cache support

Since Roan is based on a personal need, it’s based on nginx’s proxy_cache.

Suppose you have the following purge mapping:

location ~ /purge(/.*) {
    allow 127.0.0.1;
    deny all;
    proxy_cache_purge roan "$scheme://$host$1";
}

Now suppose you have the following Django model:

class Post(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField()

And you have a URL /posts where users can see a list of posts. How can you set a forever cache and expect the cache to be refreshed whenever a new post is saved? Or whenever a post gets updated or deleted?

Using Roan you’ll be able to connect one or more models to one or more URL. So you can connect the Post model with the /posts URL, and whenever a Post gets saved, updated or deleted, Roan makes a request to the /purge/posts URL.

Usage

Once you have Roan installed and configured, you just need to call it in a file that Django executes (e.g.: the models.py of your app). Here is the code for the example above, of purging the /posts URL whenever a post gets saved or deleted:

from roan import purge
from models import Post

purge("/posts").on_save(Post)
purge("/posts").on_delete(Post)