使用lambda（python）获取EC2实例的CPU利用率时的问题

Question

我想检索EC2实例的CPU利用率指标数据。为此，我在AWS lambda中尝试了以下代码，但没有输出

代码

import boto3
import sys
from datetime import datetime, timedelta
    
def lambda_handler(event, context):

  
    client = boto3.client('cloudwatch')
    response = client.get_metric_statistics(
    Namespace = 'AWS/EC2',
    Period = 300,
    StartTime = datetime.utcnow() - timedelta(seconds = 600),
    EndTime = datetime.utcnow(),
    MetricName = 'CPUUtilization',
    Statistics=['Average'], Unit='Percent',
    Dimensions = [
            {'Name': 'InstanceId', 'Value': 'i-0b9'}
        ])
    return (response)

输出：

Response:
{
  "Label": "CPUUtilization",
  "Datapoints": [],
  "ResponseMetadata": {
    "RequestId": "2c078e99-183c-49a7-bf29-1643037759e8",
    "HTTPStatusCode": 200,
    "HTTPHeaders": {
      "x-amzn-requestid": "2c078e99-183c-49a7-bf29-1643037759e8",
      "content-type": "text/xml",
      "content-length": "337",
      "date": "Fri, 11 Dec 2020 17:49:17 GMT"
    },
    "RetryAttempts": 0
  }
}