POC lambda func to strip exif from jpegs; needs to use two different bucket sources though

index.js

var path = require( 'path' );
var aws = require( 'aws-sdk' );
var exec = require( 'child_process' ).exec;
var cmd = "exiftool -Orientation='' ";
var promise = require( 'bluebird' );
var fs = require( 'fs' );

var s3 = new aws.S3({apiVersion: '2006-03-01'});

function handler( event, context ) {
  var bucketname = event.Records[0].s3.bucket.name || null;
  var key = decodeURIComponent( event.Records[0].s3.object.key.replace(/\+/g, " ") ) || null;

  if ( key === null || ['jpg', 'jpeg'].indexOf( getFileExtensionFromKey(key) ) ) {
    console.log('Skipping this file');
    context.succeed();
    return;
  }

  getJobRecordObject( bucketname, key )
    .then(ensureTmpDirectory)
    .then(downloadFileToDisk)
    .then(stripOrientationExifData)
    .then(uploadNewImage)
    .then(cleanupFile)
    .catch(console.log);
    .catch(promise.TimeoutError, function( timeoutError ) {
      console.log(timeoutError);
      context.fail();
    })
    .finally(function() {
      context.succeed();
    })

}

function getJobRecordObject( bucket, key ) {
  var _filename = path.basename( key );
  var _filepath = guid() + '_' + _filename;

  return promise.resolve({
    bucket: bucket,
    key: key,
    filename: _filename,
    filepath: _filepath,
    cmd: "exiftool -Orientation= -overwrite_original " + _filepath
  });
}


function ensureTmpDirectory( opts ) {
  return promise.try( function() {
    if ( fs.existsSync( '/tmp' ) ) {
      return opts;
    }

    fs.mkdir( '/tmp', function( err, response ) {
      if ( err ) {
        throw err;
      }
      return opts;
    }).bind(this);
  }).bind(this);
}


function downloadFileToDisk( opts ) {
  return promise.race([
    new promise( function( resolve, reject ) {
      var writeStream = fs.createWriteStream( opts.filepath );
      writeStream.on( 'error', function onWriteStreamError( writeStreamError ) {
        return reject( writeStreamError );
      });
      writeStream.on( 'finish', function onWriteStreamFinish() {
        writeStream = null;
        return resolve( opts );
      });

      s3.getObject({Bucket: opts.bucket, Key: opts.key}, function getObjectHandler( getObjectError, data ) {
        if ( getObjectError ) {
          return reject( getObjectError );
        }
        else {
          writeStream.pipe( data );
        }
      });
    }),
    new promise( function( resolve, reject ) {
      setTimeout( reject, 10000 )
    })
  ]);
}

function stripOrientationExifData( opts ) {
  return new promise( function( resolve, reject ) {
    exec( opts.cmd, function( err, stdout ) {
      if ( err ) {
        return reject( err );
      }
      if ( !~stdout.indexOf('1 image files updated') ) {
        return reject( new Error( stdout ) );
      }
      resolve( opts );
    }).bind(this)
  }).bind(this)
}

function uploadNewImage( opts ) {
  var imageBody = os.readFileSync( opts.filePath );
  var uploadData = new Buffer( imageBody, 'binary' );
  return new promise( function( resolve, reject ) {
    s3.putObject(
      {
        Bucket: opts.bucket,
        Key: opts.key,
        Body: uploadData,
        ACL: 'public-read-write',
        ContentType: 'application/octet-stream'
      },
      function( putObjectError, results ) {
        if ( putObjectError ) {
          reject( putObjectError );
        } else {
          resolve( opts );
        }
    });
  })
}

function cleanupFile( opts ) {
  try {
    os.removeSync( opts.filepath );
  } catch ( e ) {
    console.log( e );
  }
}


function getFileExtensionFromKey( key ) {
  return path.extname( path.basename( key ) ).slice(1).toLowerCase();
}


function guid() {
  function s4() {
    return Math.floor((1 + Math.random()) * 0x10000)
      .toString(16)
      .substring(1);
  }
  return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
    s4() + '-' + s4() + s4() + s4();
}


module.exports = handler;