s3-cache's Introduction

s3-cache

Caches and serves responses to and from S3. Similar to koa-cash, except it optimizes for the S3 use-case by streaming.

Usage:

let cache = require('koa-s3-cache')({
  // s3 credentials and stuff
})

app.use(function* (next) {
  // served from cache
  if (yield* cache.get(this)) return

  // do some crazy computation
  this.body = new Buffer(1024 * 1024)

  // save it to s3
  yield* cache.put(this)
})

This is best for dynamically created content that is cached (i.e. thumbnails). Instead of caching yourself in the business logic, cache transparently with this module.

API

const cache = Cache(options)

Create a cache instance.

S3 options:

key
secret
bucket

Other options:

salt - add a salt to namespace your cache instances

app.use(cache)

You can use the cache as middleware, which caches all downstream middleware.

app.use(cache)

app.use(function* () {
  this.body = 'something computationally intensive'
})

app.use(cache.wrap( next => ))

Wrap a middleware with the cache. Useful for conditional caching

app.use(cache.wrap(function* () {
  this.body = 'something computationally intensive'
}))

const served = yield cache.get(this)

Serve this request from the cache. Returns served, which is whether the response has been served from the cache.

yield cache.put(this)

Caches the current response.

Notes

You should set an object lifecycle rule. Ex. delete all files in the bucket after 7 days.
Objects are stored with REDUCED_REDUNDANCY.
Only supports 200-2 status codes.
If the body is streaming, the stream is cached to the filesystem so that the S3 client knows its content-length.

s3-cache's People