generating short lived credentials for s3

s3Accessors.js

'use strict';

var util = require('util');
var aws = require('aws-sdk');
var async = require('async');

var EXPIRATION_TIME_SECS = 60 * 60; //60 mins
var BUCKET = 'myTestBucket';
var OBJECT_PATH = 'path/where/the/object/is/store';

var ACCESS_KEY='<access_key>';
var SECRET_KEY='<secret_key>';

function initialize(params, next) {
  params.s3 = new aws.S3({
    accessKeyId: ACCESS_KEY,
    secretAccessKey: SECRET_KEY
  });
  util.log('s3 initialized');

  return next();
}

function createBucket(params, next) {
  var bucketOptions = {
    Bucket: BUCKET
  };

  util.log('Creating bucket ' + bucketOptions.Bucket);
  params.s3.createBucket(bucketOptions,
    function(err) {
      return next(err);
    }
  );
}

function generateGETUrl(params, next) {
  util.log('Generating GET url for object');

  var options = {
    Bucket: BUCKET,
    Key: OBJECT_PATH,
    Expires: EXPIRATION_TIME_SECS
  };

  params.s3.getSignedUrl('getObject', options,
    function(err, url) {
      if (err)
        return next(err);
      params.accessors.get = url;
      return next();
    }
  );
}

function generatePUTUrl(params, next) {
  util.log('Generating PUT url for object');

  var options = {
    Bucket: BUCKET,
    Key: OBJECT_PATH,
    Expires: EXPIRATION_TIME_SECS
  };

  params.s3.getSignedUrl('putObject', options,
    function(err, url) {
      if (err)
        return next(err);
      params.accessors.put = url;
      return next();
    }
  );
}

function generateDELETEUrl(params, next) {
  util.log('Generating DELETE url for object');

  var options = {
    Bucket: BUCKET,
    Key: OBJECT_PATH,
    Expires: EXPIRATION_TIME_SECS
  };

  params.s3.getSignedUrl('deleteObject', options,
    function(err, url) {
      if (err)
        return next(err);
      params.accessors.delete = url;
      return next();
    }
  );
}

function generateHEADUrl(params, next) {
  util.log('Generating HEAD url for object');

  var options = { 
    Bucket: BUCKET,
    Key: OBJECT_PATH,
    Expires: EXPIRATION_TIME_SECS
  };  

  params.s3.getSignedUrl('headObject', options,
    function(err, url) {
      if (err)
        return next(err);
      params.accessors.head = url;
      return next();
    }   
  );  
}

function main(cb) {
  var params = {};
  params.accessors = {
    get: '',
    put: '',
    delete: ''
  };

  async.series([
    initialize.bind(null, params),
    createBucket.bind(null, params),
    generateGETUrl.bind(null, params),
    generatePUTUrl.bind(null, params),
    generateDELETEUrl.bind(null, params),
    generateHEADUrl.bind(null, params)
  ], function (err) {
    if (err) {
      util.log(
        util.format(
          'Error generating accessor URLs for Bucket %s and path %s',
            BUCKET, OBJECT_PATH));
        util.log(util.inspect(err));
    } else {
      util.log('Accessors : ' + util.inspect(params.accessors));
    }

    cb();
  });
}

main(function () {
  util.log('Done');
});