ExpressJS file upload to S3

express_s3_aws-sdk-js.js

exports.new_photo = function(req, res){

  // Get File upload information  
  var filename = req.files.image.filename; // actual filename of file
  var path = req.files.image.path; //will be put into a temp directory
  var mimeType = req.files.image.type; // image/jpeg or actual mime type


  // Create a new blog post
  var photoPost = new Photo(); // create Blog object
  photoPost.title = req.body.title;
  photoPost.urltitle = req.body.title.toLowerCase().replace(/[^\w ]+/g,'').replace(/ +/g,'_')
  photoPost.caption = req.body.caption;
  
  // any file upload?
  console.log("about to upload")

  // 2) create file name with logged in user id + cleaned up existing file name. function defined below.
  cleanedFileName = cleanFileName(filename);

  // 3a) We first need to open and read the image upload into a buffer
  fs.readFile(path, function(err, file_buffer){

    // pick the Amazon S3 Bucket
    var s3bucket = new AWS.S3({params: {Bucket: 'dwd_uploads'}});
    
    // Set the bucket object properties
    // Key == filename
    // Body == contents of file
    // ACL == Should it be public? Private?
    // ContentType == MimeType of file ie. image/jpeg.
    var params = {
      Key: cleanedFileName,
      Body: file_buffer,
      ACL: 'public-read',
      ContentType: mimeType
    };
    
    // Put the Object in the Bucket
    s3bucket.putObject(params, function(err, data) {
      if (err) {
        console.log(err)

      } else {
        console.log("Successfully uploaded data to s3 bucket");

        // add image to blog post
        photoPost.image = cleanedFileName;
      }

      photoPost.save();

      res.redirect('/');

    });

  });

};

Awesome code!,
But the code deos not have a policy doc and signature.
deos it mean i don't need it for anonymous uploads to my amazon s3 bucket ?.
Thanks

I was confused about the attributes Key in params when I read the documentation then I came across this gist. Thanks.
You should handle the case fs.readFile fails.