lovell / rampart

Reverse HTTP proxy backed by distributed memory cache. Designed to protect APIs from intense GET request traffic spikes.

rampart

Reverse HTTP proxy backed by distributed memory cache. Designed to protect APIs from intense GET request traffic spikes.

• HTTP reverse proxy
• Horizontally scalable
• Stateless instances
• Backed by a memcached cluster

This is alpha-quality software and is not yet ready for use in production environments.

Install

npm install -g https://github.com/lovell/rampart/tarball/master

Usage

rampart --upstream host:port/path

Command line options

Required

--upstream   Upstream HTTP service to act as reverse proxy for in the form 'host:port/path'

Optional

--memcached  Comma separated list of memcached hosts in the form 'host1:11211,host2:11211'
             [default: "localhost:11211"]

--port       TCP port for this service to listen on
             [default: 8080]

--metrics    TCP port on which to start HTTP service providing internal metrics as JSON

Protection

• Avoids the thundering herd problem with a "dogpile" lock
• Gracefully handles memcached node failure with consistent hashing
• Can remove common client-side HTTP parameters, e.g. Google Analytics' utm_*
• Normalises variants of the same URL when generating the cache key
• Respects upstream HTTP Cache-Control response headers from the service it's protecting
• Ignores downstream HTTP Cache-Control request headers from the client
• TODO: Caches 4xx and 5xx responses

Deployment

• TODO: Easy to deploy to AWS Elastic Beanstalk
• TODO: Supports AWS Elasticache's Auto Discovery feature
• TODO: Provides metrics e.g. requests per second, cache hit rates

Current limitations

• Does not support HTTPS
• Does not respect the Vary response header
• One upstream per instance (but there can and should be many instances per upstream)

Alternatives you should consider first

nginx

nginx provides the proxy_cache feature, where each instance maintains its own filesystem cache. Think of rampart as a distributed version of nginx's "proxy_cache_use_stale updating" directive.

squid

Versions 2.6 and 2.7 (the most recent release was 2010) of Squid provide a per-instance Collapsed Forwarding feature to prevent the thundering herd problem. This feature is not available in version 3.x of Squid.

Test

Run the (currently very limited) integration tests with:

npm test