How to upload files to Amazon S3 with Meteor?

Question

I'm trying to upload files to my Amazon S3 Bucket. S3 and amazon is set up. This is the error message from Amazon:

Conflicting query string parameters: acl, policy

Policy and signature is encoded, with Crypto.js for Node.js

var crypto=Npm.require("crypto");

I'm trying to build POST request with Meteor HTTP.post method. This could be wrong as well.

    var BucketName="mybucket";
    var AWSAccessKeyId="MY_ACCES_KEY";
    var AWSSecretKey="MY_SECRET_KEY";

    //create policy
    var POLICY_JSON={
        "expiration": "2009-01-01T00:00:00Z",
            "conditions": [ 
            {"bucket": BucketName}, 
            ["starts-with", "$key", "uploads/"],
            {"acl": 'public-read'},
            ["starts-with", "$Content-Type", ""],
            ["content-length-range", 0, 1048576],
        ]   
    }
    var policyBase64=encodePolicy(POLICY_JSON);
    //create signature
    var SIGNATURE = encodeSignature(policyBase64,AWSSecretKey);
    console.log('signature: ', SIGNATURE);

This is the POST request I'm using with Meteor:

    //Send data----------
    var options={
        "params":{
            "key":file.name,
            'AWSAccessKeyId':AWSAccessKeyId,
            'acl':'public-read',
            'policy':policyBase64,
            'signature':SIGNATURE,
            'Content-Type':file.type,
            'file':file,
            "enctype":"multipart/form-data",
        }
    }

    HTTP.call('POST','https://'+BucketName+'.s3.amazonaws.com/',options,function(error,result){
        if(error){
            console.log("and HTTP ERROR:",error);
        }else{
            console.log("result:",result);
        }
    });

and her I'm encoding the policy and the signature:

encodePolicy=function(jsonPolicy){
    // stringify the policy, store it in a NodeJS Buffer object
    var buffer=new Buffer(JSON.stringify(jsonPolicy));
    // convert it to base64
    var policy=buffer.toString("base64");
    // replace "/" and "+" so that it is URL-safe.
    return policy.replace(/\//g,"_").replace(/\+/g,"-");
}

encodeSignature=function(policy,secret){
    var hmac=crypto.createHmac("sha256",secret);
    hmac.update(policy);
    return hmac.digest("hex");
}

A can't figure out whats going on. There might already be a problem at the POST method, or the encryption, because I don't know these methods too well. If someone could point me to the right direction, to encode, or send POST request to AmazonS3 properly, it could help a lot.
(I don't like to use filepicker.io, because I don't want to force the client to sign up there as well.)

Thanks in advance!!!

Answer 1

Direct uploads to S3 you can use the slingshot package:

meteor add edgee:slingshot

On the server side declare your directive:

Slingshot.createDirective("myFileUploads", Slingshot.S3Storage, {
  bucket: "mybucket",
  allowedFileTypes: ["image/png", "image/jpeg", "image/gif"],

  acl: "public-read",

  authorize: function () {
    //You can add user restrictions here
    return true;
  },

  key: function (file) {
    return file.name;
  }
});

This directive will generate policy and signature automatically.

And them just upload it like this:

var uploader = new Slingshot.Upload("myFileUploads");

uploader.send(document.getElementById('input').files[0], function (error, url) {
  Meteor.users.update(Meteor.userId(), {$push: {"profile.files": url}});
});

Answer 2

Why don't you use the aws-sdk package? It packs all the needed methods for you. For example, here's the simple function for adding a file to bucket:

s3.putObject({
  Bucket: ...,
  ACL: ...,
  Key: ...,
  Metadata: ...,
  ContentType: ...,
  Body: ...,
}, function(err, data) {
  ...
});