在 AWS SAM 模板中出现 Fn::GetAtt 错误

Question

我已经在我的 AWS 无服务器应用程序模型模板中声明了 SNS 主题和订阅，如下所示：-

MyTopic:
    Type: AWS::SNS::Topic
    Properties:
      DisplayName: !Sub 'test-${Environment}-${AWS::AccountId}-${AWS::Region}'
      Tags:
       - Key: Environment
         Value: !FindInMap [Environment, FullForm, !Ref Environment]
      TopicName: !Sub 'test-${Environment}-${AWS::AccountId}-${AWS::Region}'

  MySubscription:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !Ref SubscriptionEndPoint
      Protocol: !Ref SubscriptionProtocol
      Region: !Ref 'AWS::Region'
      TopicArn: !Ref MyTopic

然后在我的 Lambda 函数环境中使用 SNS 主题 ARN，如下所示在同一模板文件中：-

MyLambda:
    Type: AWS::Serverless::Function
    Properties:
      Environment:
        Variables:
          RUNTIME_SNS_TOPIC_ARN: !GetAtt MyTopic.Arn

输出（在 SAM 模板中）：-

MyTopic:
    Description: SNS Topic for the Ingest to send notification to
    Export:
      Name: !Sub
        - ${ExportPrefix_}:${AWS::Region}:MyTopic
        - ExportPrefix_: !If
          - HasExportPrefix
          - !Join ['-', [!Ref ExportPrefix, !Ref Environment]]
          - !Join ['-', [!Select [0, !Split ["-", !Ref "AWS::StackName"]], !Ref Environment]]
      Value: !Sub "${MyTopic.Arn}:${MyTopic.Version.Version}"
  MySubscription:
    Description: Subscription to get messages from a topic
    Export:
      Name: !Sub
        - ${ExportPrefix_}:${AWS::Region}:MySubscription
        - ExportPrefix_: !If
          - HasExportPrefix
          - !Join ['-', [!Ref ExportPrefix, !Ref Environment]]
          - !Join ['-', [!Select [0, !Split ["-", !Ref "AWS::StackName"]], !Ref Environment]]
      Value: !Sub "${MySubscription.Arn}:${MySubscription.Version.Version}"

但是，我收到以下错误:-

13:30:30 错误：无法为堆栈创建变更集：my-stack，例如：Waiter ChangeSetCreateComplete 失败：Waiter 遇到终端故障状态状态：失败。原因：模板错误：资源 MyTopic 不支持 Fn::GetAtt

中的属性类型 Arn

Answer 1

使用 Ref

时 AWS::SNS:Topic return 的 ARN

查看 return 值的 Docs。

试试

MyLambda:
    Type: AWS::Serverless::Function
    Properties:
      Environment:
        Variables:
          RUNTIME_SNS_TOPIC_ARN: !Ref MyTopic  # Using !Ref

Answer 2

建议在编写模板时尝试 CloudFormation Linter in VSCode 以查看其中一些内联错误：

[cfn-lint] E1010: Invalid GetAtt MyTopic.Arn for resource MyLambda
[cfn-lint] E1019: Parameter MyTopic.Arn for Fn::Sub not found at Outputs/MyTopic/Value/Fn::Sub
[cfn-lint] E1019: Parameter MyTopic.Version.Version for Fn::Sub not found at Outputs/MyTopic/Value/Fn::Sub
[cfn-lint] E1019: Parameter MySubscription.Arn for Fn::Sub not found at Outputs/MySubscription/Value/Fn::Sub
[cfn-lint] E1019: Parameter MySubscription.Version.Version for Fn::Sub not found at Outputs/MySubscription/Value/Fn::Sub

它还会指出 Value 需要在 Outputs

中减少缩进

AWS::SNS::Topic return values

AWS::SNS::Subscription

在 AWS SAM 模板中出现 Fn::GetAtt 错误

Getting Fn::GetAtt error in the AWS SAM template

amazon-cloudformation

aws-sam

aws-cloudformation-custom-resource