veritas-s3-transform
v3.1.2
Published
Streaming multer storage engine for AWS S3
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Readme
Veritas S3 Transform
This is a fork of Multer S3, kept up to date, with the added Transform property.
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 i veritas-s3-transform --save
Usage
var aws = require('aws-sdk')
var express = require('express')
var multer = require('multer')
var multerS3 = require('veritas-s3-transform')
var app = express()
var s3 = new aws.S3({ /* ... */ })
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
metadata: function (req, file, cb) {
cb(null, {fieldName: file.fieldname});
},
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
metadata
| The metadata
object to be sent to S3 | S3Storage
location
| The S3 url
to access the file | S3Storage
etag
| The etag
of the uploaded file in S3 | S3Storage
contentDisposition
| The contentDisposition
used to upload the file | S3Storage
storageClass
| The storageClass
to be used for the uploaded file in S3 | S3Storage
versionId
| The versionId
is an optional param returned by S3 for versioned buckets. | 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.
Setting Metadata
The metadata
option is a callback that accepts the request and file, and returns a metadata object to be saved to S3.
Here is an example that stores all fields in the request body as metadata, and uses an id
param as the key:
var opts = {
s3: s3,
bucket: config.originalsBucket,
metadata: function (req, file, cb) {
cb(null, Object.assign({}, req.body));
},
key: function (req, file, cb) {
cb(null, req.params.id + ".jpg");
}
};
Setting Cache-Control header
The optional cacheControl
option sets the Cache-Control
HTTP header that will be sent if you're serving the files directly from S3. You can pass either a string or a function that returns a string.
Here is an example that will tell browsers and CDNs to cache the file for one year:
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
cacheControl: 'max-age=31536000',
key: function (req, file, cb) {
cb(null, Date.now().toString())
}
})
})
Setting Custom Content-Type
The optional contentType
option can be used to set Content/mime type of the file. By default the content type is set to application/octet-stream
. If you want multer-s3 to automatically find the content-type of the file, use the multerS3.AUTO_CONTENT_TYPE
constant. Here is an example that will detect the content type of the file being uploaded.
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
contentType: multerS3.AUTO_CONTENT_TYPE,
key: function (req, file, cb) {
cb(null, Date.now().toString())
}
})
})
You may also use a function as the contentType
, which should be of the form function(req, file, cb)
.
Setting StorageClass
storageClass values can be set by passing an optional storageClass
parameter into the multerS3
object.
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
acl: 'public-read',
storageClass: 'REDUCED_REDUNDANCY',
key: function (req, file, cb) {
cb(null, Date.now().toString())
}
})
})
Setting Content-Disposition
The optional contentDisposition
option can be used to set the Content-Disposition
header for the uploaded file. By default, the contentDisposition
isn't forwarded. As an example below, using the value attachment
forces the browser to download the uploaded file instead of trying to open it.
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
acl: 'public-read',
contentDisposition: 'attachment',
key: function (req, file, cb) {
cb(null, Date.now().toString())
}
})
})
Using Server-Side Encryption
An overview of S3's server-side encryption can be found in the [S3 Docs] (http://docs.aws.amazon.com/AmazonS3/latest/dev/serv-side-encryption.html); be advised that customer-managed keys (SSE-C) is not implemented at this time.
You may use the S3 server-side encryption functionality via the optional serverSideEncryption
and sseKmsKeyId
parameters. Full documentation of these parameters in relation to the S3 API can be found [here] (http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#upload-property) and [here] (http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingServerSideEncryption.html).
serverSideEncryption
has two valid values: 'AES256' and 'aws:kms'. 'AES256' utilizes the S3-managed key system, while 'aws:kms' utilizes the AWS KMS system and accepts the optional sseKmsKeyId
parameter to specify the key ID of the key you wish to use. Leaving sseKmsKeyId
blank when 'aws:kms' is specified will use the default KMS key. Note: You must instantiate the S3 instance with signatureVersion: 'v4'
in order to use KMS-managed keys [[Docs]] (http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingAWSSDK.html#specify-signature-version), and the specified key must be in the same AWS region as the S3 bucket used.
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
acl: 'authenticated-read',
contentDisposition: 'attachment',
serverSideEncryption: 'AES256',
key: function(req, file, cb) {
cb(null, Date.now().toString())
}
})
})
Transforming Files Before Upload
The optional shouldTransform
option tells multer whether it should transform the file before it is uploaded. By default, it is set to false
. If set to true
, transforms
option must be added, which tells how to transform the file. transforms
option should be an Array
, containing objects with can have properties id
, key
and transform
.
var upload = multer({
storage: multerS3({
s3: s3,
bucket: 'some-bucket',
shouldTransform: function (req, file, cb) {
cb(null, /^image/i.test(file.mimetype))
},
transforms: [{
id: 'original',
key: function (req, file, cb) {
cb(null, 'image-original.jpg')
},
transform: function (req, file, cb) {
cb(null, sharp().jpg())
}
}, {
id: 'thumbnail',
key: function (req, file, cb) {
cb(null, 'image-thumbnail.jpg')
},
transform: function (req, file, cb) {
cb(null, sharp().resize(100, 100).jpg())
}
}]
})
})
If this option is used, each file passed to your router request will have a transforms
array, with every transform you defined.
{
"data": {
"fieldname": "image",
"originalname": "image.jpg",
"encoding": "7bit",
"mimetype": "image/jpg",
"transforms": [
{
"id": "thumbnail",
"size": 2440,
"bucket": "some-bucket",
"key": "image-thumbnail.jpg",
"acl": "public-read",
"contentType": "image/jpg",
"metadata": null,
"location": "https://some-bucket.s3.us-east-1.amazonaws.com/image-thumbnail.jpg",
"etag": "\"9d554e03e37c79bff7ce31d375900db6\""
},
{
"id": "original",
"size": 18006,
"bucket": "some-bucket",
"key": "image-original.jpg",
"acl": "public-read",
"contentType": "image/jpg",
"metadata": null,
"location": "https://some-bucket.s3.us-east-1.amazonaws.com/image-original.jpg",
"etag": "\"76c09df7bdd752a749f91b9663838fb2\""
},
]
}
}
Testing
The tests mock all access to S3 and can be run completely offline.
npm test