upcache

Caching proxy having cache keys configured by the upstream application, by setting http response headers.

Upcache has several ways of changing the cache keys:

• tag, version resources by zones
• lock, vary on client json web token grants
• vary, vary by grouping selected request headers
• map, maps a request uri to another request uri

Breaking change: server.d/upcache.conf is now server.d/upcache-memcached.conf

Requirements

In debian/12 these packages are easy to install:

• nginx

• libnginx-mod-http-srcache-filter

• libnginx-mod-http-set-misc

• libnginx-mod-http-memc (if using memcached, or for running the test suite

• memcached or redis

• lua-resty-core

• lua-resty-lrucache

• a Node.js express app

Install

The Node.js app need the module

npm install upcache

The nginx configuration need the module

luarocks install upcache

nginx is easily configured with the set of files described in (depending on where npm installs the module) ./node_modules/upcache/nginx/README.md.

Usage

Once installed, load appropriate helpers with

const app = express();
const { tag, lock } = require('upcache');
const mlock = lock(config);

app.get('/route', tag('ugc', 'global'), mlock.restrict('logged'), ...);
app.post('/route', tag(), mlock.restrict('logged'), ...);

See README-tag.md and README-lock.md for documentation, and test/ for more examples.

Mind that srcache module honours cache control headers - if the application sends responses with Cache-Control: max-age=0, the resource is not cached, and tag().for() is a facility for doing cache control.

To cache something, resources must be tagged, so lock/vary won't work without tag.

Detection by upstream

Upcache adds a X-Upcache: <version> header to requests, so upstream application can detect it is enabled, and which features are available.

Testing

A pre-configured nginx environment is available for testing a Node.js application that listens on port 3000, with nginx on port 3001 and memcached on port 3002, simply by launching (depending on ./node_modules/.bin being on PATH or not)

npm run upcache

which also has an option for filtering output -g <regexp pattern>.

mocha relies on it for integration tests. No root permissions are needed.

License

See LICENSE file.