Question

目标：设置一个Cloudformation堆栈，该堆栈使用一个日志组名称作为参数，每当新日志出现在该日志组中时，它们就被发送到Lambda函数进行处理，然后发送到Kinesis Firehose，然后将其发送给将文件记录到名为foobarbaz的存储桶中。

问题：Lambda函数永远不会被调用（Lambda的CloudWatch日志显示，即使在日志组中出现新数据之后，它也不会被触发）。由于我设置了SubscriptionFilter资源，因此调用应该自动发生。我没有看到任何错误。无论发生什么，似乎都在默默地失败。

注意：SubscriptionFilter上的FilterPattern已设置为空字符串。我的目的是将所有日志从日志组发送到Lambda函数。

这是我的Cloudformation模板：

Parameters:
  LogGroupName:
    Type: String
    Description: The name of the log group who's logs we want to send to send to Lambda->Kinesis->S3

  AuditTrailPrefix:
    Type: String
    Description: Log files will be sent to the Logging account S3 bucket with this prefix in the bucket path

Resources:  
  AuditTrailFunctionPermissions:
    Type: AWS::Lambda::Permission
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !Ref AuditTrailFunction
      Principal: logs.amazonaws.com
      SourceAccount: !Ref AWS::AccountId

  AuditTrailFunction:
    Type: AWS::Lambda::Function
    Properties:
      Handler: index.handler
      Role: !GetAtt AuditTrailFunctionRole.Arn
      Code:
        ZipFile: >
          // do some stuff with the data and PUT it to KinesisFirehose
          // removed for brevity
      Runtime: nodejs8.10
      Timeout: 30

  AuditTrailFunctionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
          Action: sts:AssumeRole
          Effect: Allow
          Principal:
            Service: lambda.amazonaws.com
        Version: '2012-10-17'
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      Policies:
        - PolicyDocument:
            Statement:
              - Action:
                  - firehose:PutRecord
                  - firehose:PutRecordBatch
                Effect: Allow
                Resource: !Sub arn:aws:firehose:${AWS::Region}:${AWS::AccountId}:deliverystream/${AuditTrailDeliveryStream}
            Version: '2012-10-17'
          PolicyName: root

  AuditTrailSubscription:
    Type: AWS::Logs::SubscriptionFilter
    DependsOn: AuditTrailFunctionPermissions
    Properties:
      DestinationArn: !GetAtt AuditTrailFunction.Arn
      FilterPattern: ''
      LogGroupName: !Ref LogGroupName

  AuditTrailDeliveryStream:
    Type: AWS::KinesisFirehose::DeliveryStream
    Properties:
      DeliveryStreamType: DirectPut
      S3DestinationConfiguration:
        BucketARN: arn:aws:s3:::foobarbaz
        BufferingHints:
          IntervalInSeconds: 60
          SizeInMBs: 50
        CompressionFormat: GZIP
        Prefix: !Ref AuditTrailPrefix
        RoleARN: !GetAtt DeliveryRole.Arn

  DeliveryRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
          Effect: Allow
          Principal:
            Service: firehose.amazonaws.com
          Action: sts:AssumeRole

      Policies:
        - PolicyName: firehose_delivery_policy
          PolicyDocument:
            Statement:
              Effect: Allow
              Action:
                - s3:AbortMultipartUpload
                - s3:GetBucketLocation
                - s3:GetObject
                - s3:ListBucket
                - s3:ListBucketMultipartUploads
                - s3:PutObject
              Resource:
                - arn:aws:s3:::foobarbaz
                - arn:aws:s3:::foobarbaz/${AuditTrailPrefix}*

Answer 1

我看不到任何错误，但以下是一些解决问题的提示：

仅当新日志上载到您的日志组时，才会调用Lambda函数。在设置订阅过滤器之前，不会为日志组中已经存在的数据调用它。
如果不是＃1（即您要上传新数据），请转到CloudWatch-> Metrics并搜索日志组名称。您应该找到与您的订阅筛选器相关的4个指标：ForwardedBytes，ForwardedLogEvents，DeliveryErrors，DeliveryThrottling。有关说明，请参见this。如果DeliveryErrors或DeliveryThrottling指标大于0，则说明存在问题。
DeliveryErrors最可能的问题是权限问题。我没有发现您的问题，但这是我首先要仔细检查的问题。
您可以使用AWS CLI手动调试订阅设置。（请参见this。）这可以帮助您找出是哪一部分设置可能导致了问题。

Answer 2

我怀疑这是因为您的 RoleArn 资源中缺少 AuditTrailSubscription。没有它，Cloudwatch 无权执行您的 Lambda 函数。

这是 AWS::Logs::SubscriptionFilter 的文档页面 https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-logs-subscriptionfilter.html

尽管有SubscriptionFilter，但AWS CloudWatch LogGroup从未将日志发送到Lambda

2 个答案: