title: Saving an image stored on s3 using node.js?
body: <p>I'm trying to write an image server that uses node.js to store images on s3. Uploading the image works fine, and I can download and view it correctly using an s3 browser client (I'm using dragondisk, specifically, but I've successfully downloaded it with other ones too), but when I download it with node and try to write it to disk, I'm unable to open the file (it says it may be damaged or use a file format that Preview does not recognize). I'm using the amazon sdk for node and fs to write the file. I know that you can pass an optional encoding to fs.writeFile, but I've tried them all and it doesn't work. I've also tried setting ContentType on putObject and ResponseContentType on getObject, as well as ContentEncoding and ResponseContentEncoding (and all of these things in various combinations). Same result. Here's some code:</p>
  
  <pre><code>var AWS = require('aws-sdk')
    , gm = require('../lib/gm')
    , uuid = require('node-uui')
    , fs = require('fs');
  
  AWS.config.loadFromPath('./amazonConfig.json');
  var s3 = new AWS.S3();
  
  var bucket = 'myBucketName'; // There's other logic here to set the bucket name.
  
  exports.upload = function(req, res) {
      var id = uuid.v4();
      gm.format("/path/to/some/image.jpg", function(format){
          var key = req.params.dir + "/" + id + "/default." + format;
          fs.readFile('/path/to/some/image.jpg', function(err, data){
              if (err) { console.warn(err); }
              else {
                  s3.client.putObject({
                      Bucket: bucket,
                      Key: key,
                      Body: data,
                      ContentType: 'image/jpeg'
                      // I've also tried adding ContentEncoding (in various formats) here.
                   }).done(function(response){
                      res.status(200).end(JSON.stringify({ok:1, id: id}));
                  }).fail(function(response){
                      res.status(response.httpResponse.statusCode).end(JSON.stringify(({err: response})));
                  });
              }
          });
      });
  };
  
  exports.get = function(req, res) {
      var key = req.params.dir + "/" + req.params.id + "/default.JPEG";
      s3.client.getObject({
          Bucket: bucket, 
          Key:  key,
          ResponseContentType: 'image/jpeg'
          // Tried ResponseContentEncoding here in base64, binary, and utf8
      }).done(function(response){
          res.status(200).end(JSON.stringify({ok:1, response: response}));
          var filename = '/path/to/new/image/default.JPEG';
          fs.writeFile(filename, response.data.Body, function(err){
              if (err) console.warn(err);
              // This DOES write the file, just not as an image that can be opened.
              // I've tried pretty much every encoding as the optional third parameter
              // and I've matched the encodings to the ResponseContentEncoding and
              // ContentEncoding above (in case it needs to be the same)
          });
      }).fail(function(response){
          res.status(response.httpResponse.statusCode).end(JSON.stringify({err: response}));
      });
  };
  </code></pre>
  
  <p>Incidentally, I'm using express for routing, so that's where req.params comes from.</p>