为什么 Cloudwatch 在没有事件发生时触发 lambda？

Question

我正在关注 CloudTrail 和 CloudWatch 上的 AWS 教程，并使用它来设置一个规则，该规则将在 S3 存储桶上发生 PUT 操作时触发 Lambda。 lambda 将打印存储桶的名称和其他详细信息。

import json
import urllib.parse
import boto3

# instantiate an S3 object
s3 = boto3.client('s3')

def lambda_handler(event, context):
    # Start processing by looking at Records key-value
    try:
        records = event['Records']
        if len(records) == 0:
            raise Exception("Records was zero!")
        else:
            packet = []
            for row in records:
                msg = "Received event type - {}".format(row["eventName"]) + \
                " caused by user - {}".format(
                    row["userIdentity"]["principalId"]) + \
                    " on bucket - {}".format(row["s3"]["bucket"]["name"]) + \
                    " whose owner is - {}".format(
                        row["s3"]["bucket"]["ownerIdentity"]["principalId"]) + \
                        " The specific object that got put was {}".format(
                            row["s3"]["object"]["key"]
                            )
                print(msg)
                packet.append(
                    {
                        "eventName":row["eventName"],
                        "userIdentity":row["userIdentity"]["principalId"],
                        "bucket":row["s3"]["bucket"]["name"],
                        "bucketOwner":row["s3"]\
                        ["bucket"]["ownerIdentity"]["principalId"],
                        "objectKey":row["s3"]["object"]["key"]
                        }                   )
            return {"statusCode":200, "body":packet}
    except:
        raise Exception("Could not find Records from Events")

我注意到，在 Cloudwatch 日志中（在日志组下），每当我将文件放在 S3 存储桶下时，我都会看到 S3 存储桶的所有活动。 但也有例外情况 -> 无法从事件中找到记录 - 存在。

为什么在这种情况下会触发 Lambda？

Answer 1

您能否打印异常并查看引发的异常是什么。

Answer 2

替代解决方案 - 如果 cloudwatch 出现错误。您可以在 s3 中使用通知配置。这将在 s3 中创建对象时调用 lambda。

Resources: bucket1: Type: AWS::S3::Bucket Properties: BucketName: !Ref SourceBucket NotificationConfiguration: LambdaConfigurations: - Event: 's3:ObjectCreated:*' Function: !GetAtt LambdaFunction.Arn BucketPermission: Type: AWS::Lambda::Permission Properties: Action: 'lambda:InvokeFunction' FunctionName: !Ref LambdaFunction Principal: s3.amazonaws.com SourceArn: !Sub arn:aws:s3:::${SourceBucket}