只有当消息计数达到SQS中的目标值时,才能触发lambda吗？

Question

我正在编写AWS Lambda来从SQS读取消息,然后在过滤后将一些消息保存到S3.由于80%的消息将被过滤掉,我决定为100000个SQS消息写一次S3.

仅当SQS中的消息达到10000时才可以触发Lambda吗？

Answer 1

借助AWS CloudWatch可以实现这一目标.

您可以配置AWS CloudWatch警报,一旦SQS队列获得100000条可见消息,就会触发"AlarmAction".如果出现"警报",您将通知SNS主题,然后触发您的AWS Lambda.

如果您使用的是AWS CloudFormation,则可能如下所示:

AWSTemplateFormatVersion: 2010-09-09
Resources:
  Queue:
    Type: AWS::SQS::Queue

  QueueVisibleMessagesTopic:
    Type: AWS::SNS::Topic

  LambdaExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

  Lambda:
    Type: AWS::Lambda::Function
    Properties:
      Handler: handler.index
      Role: !GetAtt LambdaExecutionRole.Arn
      Runtime: nodejs8.10
      MemorySize: 128
      Timeout: 10

  LambdaSubscription:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !GetAtt Lambda.Arn
      Protocol: lambda
      TopicArn: !Ref QueueVisibleMessagesTopic

  LambdaSubscriptionPermissions:
    Type: AWS::Lambda::Permission
    Properties:
      FunctionName: !GetAtt Lambda.Arn
      Action: lambda:InvokeFunction
      Principal: sns.amazonaws.com
      SourceArn: !Ref QueueVisibleMessagesTopic

  QueueVisibleMessagesAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      Namespace: AWS/SQS
      MetricName: ApproximateNumberOfMessagesVisible
      Dimensions:
        - Name: QueueName
          Value: !GetAtt Queue.QueueName
      Statistic: Sum
      Period: 300
      EvaluationPeriods: 1
      ComparisonOperator: GreaterThanOrEqualToThreshold
      Threshold: 100000
      AlarmActions:
        - !Ref QueueVisibleMessagesTopic