aws-s3-form

Generate a signed and ready to use formdata to put files to S3 directly from the browser. Signing is done by using AWS Signature Version 4

Install

  npm install aws-s3-form

Initialize

  var AwsS3Form = require( "aws-s3-form" );

  var formGen = new AwsS3Form({
  	accessKeyId:		"your-access-key",
  	secretAccessKey:	"your-secret",
  	region:				"us-east-1",
  	bucket:				"my-bucket-name",
  	redirectUrlTemplate:"http://localhost:3010/redir/<%= filename %>"
  });

Basic Usage

formdata = formGen.create( "my-s3-filename-or-key" )
/*

	{
		action: "http://my-bucket-name.s3.amazonaws.com/",		// The form action url. Make sure to add also `method="POST" enctype="multipart/form-data`
		filefield: "file",										// Name of the input field to upload a single file to S3.
		fields: {												// Hidden fields to add to the form. Object-key = form-name and object-value = form-value
			key: "my-s3-filename-or-key",
			acl: "public-read",
			success_action_redirect: "http://localhost:3010/redir/my-s3-filename-or-key",
			"X-Amz-Credential": "your-access-key/20150108/us-east-1/s3/aws4_request",
			"X-Amz-Algorithm": "AWS4-HMAC-SHA256",
			"X-Amz-Date": "20150108T103146Z",
			"Policy": "eyJleHBpcmF0aW9uIj ... generated base64 policy ... XdpdGgiLCI",
			"X-Amz-Signature": "4732d1 ... generated signature ... 1ac65d171a"
		}
	}

 */

Config

• accessKeyId ( String required ) AWS access key
• secretAccessKey ( String required ) AWS access secret
• region ( String required ) AWS region
• bucket ( String required ) AWS bucket name
• secure ( Boolean optional: default = true ) Define if the action uses ssl. true = "https"; false = "http"
• redirectUrlTemplate ( String|Function optional ) a redirect url template.
• successActionStatus ( String|Number optional: default = 204 ) HTTP code to return when no redirectUrlTemplate is defined.
• policyExpiration ( Date|Number optional: default = 43200 ) Add time in seconds to now to define the expiration of the policy. Or set a hard Date ( 43200 = 12 hours ).
• keyPrefix ( String optional: default = `` ) Key prefix to define a policy that the key has to start with this value
• acl ( String optional: default = public-read ) The standard acl type. Only private, public-read, public-read-write, authenticated-read, bucket-owner-read and bucket-owner-full-control are allowed
• useUuid ( Boolean optional: default = true ) Use a uuid for better security
• cryptoModule ( String optional: default = crypto; enum: crypto,crypto-js ) You can switch between the node internal crypo-module or the browser module cryptojs.
  INFO: If you want to use crypto-js you have to add/install it separately with npm install crypto-js.

Security Warning!

Do not hard code the secretAccessKey in your code if you want to open source it! ;-)

Methods

.create( filename [, options ] )

Create new signed and ready to use formdata.

Arguments

• filename : ( String required ): The S3 file key/filename to use.
• options : ( Object optional ): Options to change the configured behavior
• options.acl : ( String optional; default = config.acl ): Change the configured standard acl type. Only private, public-read, public-read-write, authenticated-read, bucket-owner-read and bucket-owner-full-control are allowed
• options.keyPrefix : ( String optional; default = config.keyPrefix ): Change the configured standard keyPrefix type. Details see config object description.
• options.contentType : ( String|Boolean optional; ): Option to set the content type of the uploaded file. This could be a string with a fixed mime or a boolean to decide if the mime will be guessed by the filename.
• options.customConditions : ( Array optional; ): Option to set s3 upload conditions. For details see http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
• options.redirectUrlTemplate : ( String optional; default = config.redirectUrlTemplate ): Change the configured standard redirectUrlTemplate type. Details see config object description.
• options.successActionStatus : ( String|Number optional; default = config.successActionStatus ): Change the configured standard successActionStatus type. Details see config object description.
• options.policyExpiration : ( Date|Number optional; default = config.policyExpiration ): Change the configured standard policyExpiration type. Details see config object description.

Return

( Object ): Data needed to generate a form that can upload files directly to AWS S3.

• action : ( String ) The form action url. Make sure to add also the attributes method="POST" enctype="multipart/form-data
• filefield : ( String ) Name of the input field to upload a single file to S3.
• fields : ( Object ) Hidden fields to add to the form. Object-key = form-name and object-value = form-value.

.policy( filename [, options ] )

Create a new AWS S3 policy object based on AWS Signature Version 4.

Arguments

• filename : ( String required ): The S3 file key/filename to use.
• options : ( Object optional ): Options to change the configured behavior
• options.now : ( Date optional; default = new Date() ): The current date-time for this policy
• options.uuid : ( String optional;): The uuid to add to the policy
• options.acl : ( String optional; default = config.acl ): Change the configured standard acl type. Only private, public-read, public-read-write, authenticated-read, bucket-owner-read and bucket-owner-full-control are allowed
• options.keyPrefix : ( String optional; default = config.keyPrefix ): Change the configured standard keyPrefix type. Details see config object description.
• options.customConditions : ( Array optional; ): Option to set s3 upload conditions. For details see http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
• options.redirectUrlTemplate : ( String optional; default = config.redirectUrlTemplate ): Change the configured standard redirectUrlTemplate type. Details see config object description.
• options.successActionStatus : ( Number optional; default = config.successActionStatus ): Change the configured standard successActionStatus type. Details see config object description.
• options.policyExpiration : ( Date|Number optional; default = config.policyExpiration ): Change the configured standard policyExpiration type. Details see config object description.

Return

( Object ): A valid S3 POST policy.

Details see AWS Docs: Creating a POST Policy.

.sign( policyB64 [, options ] )

Create a AWS Signature Version 4. This is used to create the signature out of the policy.

Arguments

• policyB64 : ( String required ): Base64 encoded policy.
• options : ( Object optional ): Options to change the configured behavior
• options.now : ( Date optional; default = new Date() ): The current date-time for this signature
• options.signdate : ( String optional; default = converted options.now ): signature date
• options.secretAccessKey : ( String optional; default = config.secretAccessKey ): Change the configured standard secretAccessKey type. Details see config object description.
• options.region : ( String optional; default = config.region ): Change the configured standard region type. Details see config object description. Return

( Object ): AWS Signature Version 4.

Details see AWS Docs: Authenticating Requests in Browser-Based Uploads Using POST (AWS Signature Version 4)

Example Server

You can see a working example express server here and the corresponding jade template here.

Use Cases

use origin filename as S3 key/filename

It is a typical use case to reuse the original filename as s3 key. To handle this correctly this is the example to do it correctly.

  var AwsS3Form = require( "aws-s3-form" );

  var formGen = new AwsS3Form({
  	accessKeyId:		"your-access-key",
  	secretAccessKey:	"your-secret",
  	region:				"us-east-1",
  	bucket:				"my-bucket-name",
  	redirectUrlTemplate:"http://localhost:3010/redir/*"
  });
  
  var myForm = formGen.create( "${filename}" );
  
  / ... handle the data

The key points are, that you have to specify:

• the redirect with * at the end
• the filename with the placeholder ${filename}

This is also implemented within the example server as special case

Requested by jontelm #1

Todos

• Mimetype guessing based on the given key/filename
• Better policy generator to be able to add mimetype, filesize, ... policies.
• get credentials by environment variables or Shared Credentials File. Details

Development and Testing

If you want to contribute you have to clone the git repository and init it:

npm install
grunt build

Then configure the tests by copy the file _skeleton_config_test.json to config_test.json and fill in the correct data. Then you are able to run grunt test or start the express example in test/server.js.

Code docs

The code docs can be found here.

Release History

Version	Date	Description
0.3.3	2015-11-13	Added a option cryptoModule to select crypto or crypto-js as internal crypto module. (thanks to retorquere and Ilya Shindyapin)
0.3.2	2015-11-06	Moved from mime to mime-nofs to use this module inside external modules like react-native or within the browser (thanks to retorquere)
0.3.1	2015-08-26	Added all possible acl options and fixed numeric custom conditions (thanks to retorquere);
0.3.0	2015-05-27	Added contentType to options and optional customConditions to define a custom aws-s3 policy
0.2.0	2015-04-07	Added option successActionStatus to make ajax form posts possible
0.1.4	2015-03-17	Added option secure to create method
0.1.2	2015-03-17	Added option secure to define the http type (http or https)
0.0.5	2015-01-26	Updated readme and optimized example server
0.0.4	2015-01-09	Initial version.

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The MIT License (MIT)

Copyright © 2015 Mathias Peter, http://www.tcs.de

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.