Redis-Express caching middleware

This library implements an Express middleware that allows for caching of HTML / JSON web responses using a Redis store.

Note:

• This library has a hard-dependency on the Node Redis NPM package_
• This middleware will only cache requests that return a 200 HTTP status code

Installation

npm install --save redis-express-cache

Usage Examples

Initialize the middleware using a Redis client:

/*
Scenario:
- You have an already existing node-redis instance
- Connected node-redis instance is passed to the cache-redis middleware
*/

var app = express()();
var redis_cache = require('redis-express-cache');
var redis = require('redis');

var client = redis.createClient();

var options = { client: redis_client };

redis_cache = redis_cache(options).middleware;

app.get('/url_to_cache', function (req, res) {
  res.send('Will cache this response!')
}, redis_cache)

app.listen(3000, function () {
  console.log('Starting up!')
});

Initialize the middleware without a Redis client [connection options are provided]:

/*
Scenario:
- A connected Redis client is not provided
- Connection options ( host and port ) are provided instead
- Middleware will attempt a connection on provided connection params
*/

var app = express()();
var redis_cache = require('redis-express-cache');
var connection_options = { port: 6379, host: 'localhost' }

redis_cache = redis_cache(connection_options).middleware;

app.get('/url_to_cache', function (req, res) {
  res.send('Will cache this response!')
}, redis_cache)

Initialize the middleware without a Redis client [connection options are not provided]:

/*
Scenario:
- A connected Redis client is not provided
- Connection options ( host and port ) are not provided either
- Middleware will attempt a connection to Redis on default values ( localhost : 6379 )
*/

var app = express()();
var redis_cache = require('redis-express-cache')().middleware;

app.get('/url_to_cache', function (req, res) {
  res.send('Will cache this response!')
}, redis_cache)

Enable cache invalidation through URL query params:

/*
Scenario:
- For a cached URL : http://www.example-domain.com/cached_path
- Purge it using   : http://www.example-domain.com/cached_path?refresh_cache=8c8c279a7a98069d432271c8db9d7df2
*/

var hash_value = '8c8c279a7a98069d432271c8db9d7df2'
var refresh_key = 'refresh_cache';

var options = {
  invalidate: {
    param_key: refresh_key,
    param_value: hash_value
  }
}

var redis_cache = redis_cache(options).middleware;

app.get('/url_to_cache', function (req, res) {
  res.send('Will cache this response!')
}, redis_cache)

Available options:

Redis client

• Pass in a Redis client that the middleware can use as a cache store
• When present, the provided client will be used
• When absent, the middleware will attempt a connection to a client on localhost

/* Usage */
var options = { client: redis.createClient() }

TTL

• Provide a number in seconds that dictates the cache duration
• When present, the given URL will be cached for given seconds
• When absent, the given URL will be cached without an expiry

/* Usage */
var options = { ttl: 86400 } /* Cache for 1 day */

Include host

• Enables usage of cache keys that include host + url path instead of just the url path (default)
• When disabled a cache key will consist only of the url => /some/random/path
• When enabled a cache key will include the host as well => www.some-domain.com/some/random/path

/* Usage */
var options = { include_host: true } /* Cache for 1 day */

Enable cache invalidation via GET query params

• Allows for easy invalidation of cache entries by appending a GET param to the concerned URL
• Example:
  • Cached URL => https://www.url.com/path_to_cache
  • Can be invalidated by calling https://www.url.com/path_to_cache?refresh_cache=true

/* Usage */
var options = {
  invalidate: {
    param_key: 'refresh_cache',
    param_value: 'true'
  }
}