aws sts assume role from jenkinsfile

Jenkinsfile.groovy

// Receive a json and returns a groovy map
def _dict_from_json(json){
  json = json.replaceAll("\\{", "[")
  json = json.replaceAll("\\}", "]")
  def map = evaluate(json)
  return map
}

def _aws_assume_role(arn, session_name){
  def _script = "aws sts assume-role --role-session-name ${session_name} --role-arn ${arn}"
  def assume_role_output = sh (script: _script, returnStdout: true)
  return assume_role_output
}

node ('master'){
  stage('test') {
    def json_output = _aws_assume_role(arn, "session-name")
    def assume_role = _dict_from_json(json_output)
    echo assume_role.Credentials.SecretAccessKey
    echo assume_role.Credentials.AccessKeyId
    echo assume_role.Credentials.SessionToken
  }
}