title: aws s3 upload fail only at production envrionment, but success at local environment
body: <p>I tried to upload image using aws-sdk, multer-s3.
  In my local environment, uploading image was succeed, but in production environment(aws lambda), it fail with error status 403 forbidden.
  But my aws credential key and secret-key is same as local environment. also i checked aws key in production environment successfully. </p>
  
  <p>I think difference between two other environment is nothing.What am I missing?</p>
  
  <p>I have even tried setting aws key in my router code like below, but it also failed.</p>
  
  <pre><code>AWS.config.accessKeyId = 'blabla';
  AWS.config.secretAccessKey = 'blalbla';
  AWS.config.region = 'ap-northeast-2';
  </code></pre>
  
  <p>and here is my policy </p>
  
  <pre><code>{
      "Id": "Policy1536755128154",
      "Version": "2012-10-17",
      "Statement": [
          {
              "Sid": "Stmt1536755126539",
              "Action": [
                  "s3:DeleteObject",
                  "s3:GetObject",
                  "s3:PutObject"
              ],
              "Effect": "Allow",
              "Resource": "arn:aws:s3:::elebooks-image/*",
              "Principal": "*"
          }
      ]
  }
  </code></pre>