Multer S3

Streaming multer storage engine for AWS S3.

This project is mostly an integration piece for existing code samples from Multer's storage engine documentation with s3fs as the substitution piece for file system. Existing solutions I found required buffering the multipart uploads into the actual filesystem which is difficult to scale.

Installation

npm install --save multer-s3

Usage

var aws = require('aws-sdk')
var express = require('express')
var multer = require('multer')
var multerS3 = require('multer-s3')

var app = express()
var s3 = new aws.S3({ /* ... */ })

var upload = multer({
  storage: multerS3({
    s3: s3,
    bucket: 'some-bucket',
    key: function (req, file, cb) {
      cb(null, Date.now().toString())
    }
  })
})

app.post('/upload', upload.array('photos', 3), function(req, res, next) {
  res.send('Successfully uploaded ' + req.files.length + ' files!')
})

File information

Each file contains the following information exposed by multer-s3:

Key	Description	Note
`size`	Size of the file in bytes
`bucket`	The bucket used to store the file	`S3Storage`
`key`	The name of the file	`S3Storage`
`acl`	Access control for the file	`S3Storage`
`contentType`	The `mimetype` used to upload the file	`S3Storage`
`location`	The S3 `url` to access the file	`S3Storage`
`etag`	The `etag`of the uploaded file in S3	`S3Storage`

Setting ACL

ACL values can be set by passing an optional acl parameter into the multerS3 object.

var upload = multer({
  storage: multerS3({
    s3: s3,
    bucket: 'some-bucket',
    acl: 'public-read',
    key: function (req, file, cb) {
      cb(null, Date.now().toString())
    }
  })
})

Available options for canned ACL.

ACL Option	Permissions added to ACL
`private`	Owner gets `FULL_CONTROL`. No one else has access rights (default).
`public-read`	Owner gets `FULL_CONTROL`. The `AllUsers` group gets `READ` access.
`public-read-write`	Owner gets `FULL_CONTROL`. The `AllUsers` group gets `READ` and `WRITE` access. Granting this on a bucket is generally not recommended.
`aws-exec-read`	Owner gets `FULL_CONTROL`. Amazon EC2 gets `READ` access to `GET` an Amazon Machine Image (AMI) bundle from Amazon S3.
`authenticated-read`	Owner gets `FULL_CONTROL`. The `AuthenticatedUsers` group gets `READ` access.
`bucket-owner-read`	Object owner gets `FULL_CONTROL`. Bucket owner gets `READ` access. If you specify this canned ACL when creating a bucket, Amazon S3 ignores it.
`bucket-owner-full-control`	Both the object owner and the bucket owner get `FULL_CONTROL` over the object. If you specify this canned ACL when creating a bucket, Amazon S3 ignores it.
`log-delivery-write`	The `LogDelivery` group gets `WRITE` and `READ_ACP` permissions on the bucket. For more information on logs.

Testing

The tests mock all access to S3 and can be run completely offline.