将 DescribeStep 与 AWS SDK 或 CLI 配合使用

以下命令描述集群中步骤 ID 为 s-3LZC0QUT43AM 和集群 ID 为 j-3SD91U2E1L2QX 的步骤：

aws emr describe-step --cluster-id j-3SD91U2E1L2QX --step-id s-3LZC0QUT43AM

输出：

{
    "Step": {
        "Status": {
            "Timeline": {
                "EndDateTime": 1433200470.481,
                "CreationDateTime": 1433199926.597,
                "StartDateTime": 1433200404.959
            },
            "State": "COMPLETED",
            "StateChangeReason": {}
        },
        "Config": {
            "Args": [
                "s3://us-west-2.elasticmapreduce/libs/hive/hive-script",
                "--base-path",
                "s3://us-west-2.elasticmapreduce/libs/hive/",
                "--install-hive",
                "--hive-versions",
                "0.13.1"
            ],
            "Jar": "s3://us-west-2.elasticmapreduce/libs/script-runner/script-runner.jar",
            "Properties": {}
        },
        "Id": "s-3LZC0QUT43AM",
        "ActionOnFailure": "TERMINATE_CLUSTER",
        "Name": "Setup hive"
    }
}

def describe_step(cluster_id, step_id, emr_client):
    """
    Gets detailed information about the specified step, including the current state of
    the step.

    :param cluster_id: The ID of the cluster.
    :param step_id: The ID of the step.
    :param emr_client: The Boto3 EMR client object.
    :return: The retrieved information about the specified step.
    """
    try:
        response = emr_client.describe_step(ClusterId=cluster_id, StepId=step_id)
        step = response["Step"]
        logger.info("Got data for step %s.", step_id)
    except ClientError:
        logger.exception("Couldn't get data for step %s.", step_id)
        raise
    else:
        return step