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

然后在同一个模板文件中，在我的Lambda函数的环境中使用SNS主题ARN：-

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，我收到以下错误消息：-

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：FAILED。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AWS::SNS:Topic时，Ref返回ARN

检查返回值上的Docs。

尝试

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

Answer 2

建议在创作模板时尝试在CloudFormation Linter中的VSCode内联查看其中一些错误：

[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

还要指出，Value在Outputs中应减少缩进量

---

AWS::SNS::Topic return values

AWS::SNS::Subscription