generateSignedUrl.py

def uploadImage(event, params):
  ''' create a signedurl for client to upload image to s3'''
  # extract path (object key) from requester
  path = event['path']

  # mock key (please remove when used in lambda)
  KEY = ''
  PW = ''
  s3 = boto3.client('s3',
                    aws_access_key_id = KEY,
                    aws_secret_access_key = PW,
                    )
  #parameters for generating the signedurl                  
  parameters = {
    'Bucket' : 'hatari-expense-image',
    'Key' : path
  }
  # generate signedurl using s3 sdk
  signedUrl = s3.generate_presigned_url(
      'put_object',
      Params = parameters,
      ExpiresIn = 300
  )
  # return signedurl
  return {
      'statusCode' : 200,
      'signedUrl': signedUrl
  }