子到子参数的 Cloudformation 嵌套堆栈模板 ValidationError

Question

我制作了一个嵌套的 cloudformation 父模板，然后引用 4 个子模板。当我尝试通过 CLI 命令aws cloudformation create-stack... 启动堆栈时，出现错误：

An error occurred (ValidationError) when calling the CreateStack 
operation: Template error: instance of Fn::GetAtt references undefined 
resource BatchScatterGatherSubmissionActivity

这是因为我有一个名为 StepFunctionResourcesStack 的子模板，其中包含 BatchScatterGatherSubmissionActivity，然后是另一个引用它的子模板 EC2InstanceResourcesStack。我确保为后一个子模板添加了 DependsOn 子句，但我仍然收到错误消息。

这里是 StepFunctionResourcesStack：

---

AWSTemplateFormatVersion: '2010-09-09'
Description: step functions resources stack.
Parameters:
  StackUID:
    Type: String 

Resources:
  StatesExecutionRole:
    Type: "AWS::IAM::Role"
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service:
                - !Sub states.${AWS::Region}.amazonaws.com
            Action: "sts:AssumeRole"
      Path: "/"
      Policies:
        - PolicyName: StatesExecutionPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - "lambda:InvokeFunction"
                Resource: "*"

  MyStateMachine:
    Type: "AWS::StepFunctions::StateMachine"
    Properties:
      #
      # The StateMachine definition is substituted in with Jinja2
      #
      DefinitionString: !Sub
        - |
          {{ machine_json | indent(10) }}
        - {% for item in machine_args -%}
          {{ item }}
          {% endfor %}

      RoleArn: !GetAtt [ StatesExecutionRole, Arn ]

  # several of these:

  BatchScatterGatherSubmissionActivity:
    Type: "AWS::StepFunctions::Activity"
    Properties:
      Name:
        Fn::Join: [ "-", [ "BatchScatterGatherSubmissionActivity", Ref: StackUID] ]

  BatchScatterGatherPollingActivity:
    Type: "AWS::StepFunctions::Activity"
    Properties:
      Name:
        Fn::Join: [ "-", [ "BatchScatterGatherPollingActivity", Ref: StackUID] ]

  BatchGatherActivity:
    Type: "AWS::StepFunctions::Activity"
    Properties:
      Name:
        Fn::Join: [ "-", [ "BatchGatherActivity", Ref: StackUID] ]

  BatchTriodenovoActivity:
    Type: "AWS::StepFunctions::Activity"
    Properties:
      Name:
        Fn::Join: [ "-", [ "BatchTriodenovoActivity", Ref: StackUID] ]

  BatchHandoffActivity:
    Type: "AWS::StepFunctions::Activity"
    Properties:
      Name:
        Fn::Join: [ "-", [ "BatchHandoffActivity", Ref: StackUID] ]    

Outputs:
  # These get used in the instance_resources child stack.
  BatchScatterGatherSubmissionActivity:
    Value: !Ref BatchScatterGatherSubmissionActivity
  BatchScatterGatherPollingActivity:
    Value: !Ref BatchScatterGatherPollingActivity
  BatchGatherActivity:
    Value: !Ref BatchGatherActivity
  BatchTriodenovoActivity:
    Value: !Ref BatchTriodenovoActivity
  BatchHandoffActivity:
    Value: !Ref BatchHandoffActivity

这里是父（嵌套）模板的相关部分，上面的输出被传递到 EC2InstanceResourcesStack：

  StepFunctionResourcesStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      Parameters:
        StackUID:
          Ref: StackUID
      TemplateURL: https://s3.amazonaws.com/CFNTemplate/step_functions_resources.stack.yaml
      Timeout: "100"  


  EC2InstanceResourcesStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      Parameters:
        BatchScatterGatherSubmissionActivity: 
          Fn::GetAtt: [ "BatchScatterGatherSubmissionActivity", "Outputs.StepFunctionResourcesStack" ]
        BatchScatterGatherPollingActivity: 
          Fn::GetAtt: [ "BatchScatterGatherPollingActivity", "Outputs.StepFunctionResourcesStack" ]
        BatchGatherActivity: 
          Fn::GetAtt: [ "BatchGatherActivity", "Outputs.StepFunctionResourcesStack" ]
        BatchTriodenovoActivity: 
          Fn::GetAtt: [ "BatchTriodenovoActivity", "Outputs.StepFunctionResourcesStack" ]
        BatchHandoffActivity: 
          Fn::GetAtt: [ "BatchHandoffActivity", "Outputs.StepFunctionResourcesStack" ]
        Subnet: !Ref Subnet
        GPCESSHKeyPair: !Ref GPCESSHKeyPair
        GPCESubnetAZ1: !Ref GPCESubnetAZ1
        ActivityAndHandoffAnsibleBucketName: !Ref ActivityAndHandoffAnsibleBucketName
        ActivityAndHandoffAnsibleKeyName: !Ref ActivityAndHandoffAnsibleKeyName
        ActivityAndHandoffDaemonBucketName: !Ref ActivityAndHandoffDaemonBucketName
        ActivityAndHandoffDaemonKeyName: !Ref ActivityAndHandoffDaemonKeyName
        ActivityAndHandoffDaemonRequirementsBucketName: !Ref ActivityAndHandoffDaemonRequirementsBucketName
        ActivityAndHandoffDaemonRequirementsKeyName: !Ref ActivityAndHandoffDaemonRequirementsKeyName
        Rkstr8PkgBucketName: !Ref Rkstr8PkgBucketName
        Rkstr8PkgKeyName: !Ref Rkstr8PkgKeyName
      TemplateURL: https://s3.amazonaws.com/CFNTemplate/instance_resources.stack.yaml
      Timeout: "100"
    DependsOn: StepFunctionResourcesStack

对于我从子级导出参数并通过父模板将它们传递给另一个的方法，我遵循此处答案中提供的方法：AWS CloudFormation: Passing Values between Nested Stacks

Answer 1

您不能直接从另一个模板中的一个模板引用资源（通过Ref），即使它们是父子模板或兄弟模板。这些资源是特定于堆栈的，除非它们通过Output 部分显式导出。

所以你有两个选择：

选项 1：通过 Output 部分从子模板 1 中导出您关心的 BatchScatterGatherSubmissionActivity 值，然后将这些值导入子模板 2。

例如：

在“源”模板中：

"Outputs" : {
  "MyValue" : {
    "Value" : {
      "Ref" : "BatchScatterGatherSubmissionActivity"
    },
    "Export" : {
      "Name" : "MyExportedValue"
    }
  }
}

然后在您的“消费”模板中导入值：

{ "Fn::ImportValue" : "MyExportedValue" }

更多信息：https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-stack-exports.html

一个缺点是您不能“DependsOn”。此外，从字面上看，子模板 2 依赖于子模板 1。

选项 2： 从子模板中输出您关心的 BatchScatterGatherSubmissionActivity 值（即到父模板），然后将这些值从父模板传递到另一个孩子。

所以在子模板 1 中，您将从子堆栈中输出值：

"Outputs" : {
  "MyValue" : {
    "Value" : {
      "Ref" : "BatchScatterGatherSubmissionActivity"
    }
  }
}

在子模板 2 中，您可以通过“参数”部分向模板添加参数，然后引用该参数。

"Parameters" : {
  "MyParam" : {
    "Type" : "String",
    "Description" : "The value from elsewhere"
  }
}

然后

{ "Ref" : "MyParam" }

最后，通过将子模板 1 的输出传递到子模板 2 的参数中，将 2 个子堆栈在父级中挂钩：

"ChildStack2": {
  "Type" : "AWS::CloudFormation::Stack",
  "Properties" : {
    "Parameters" : {
      "MyParam" : { "Fn::GetAtt" : "Outputs.MyValue" }
    }
  }
}

在这种情况下，在子堆栈 1 准备好并输出它的值之前，不会创建子堆栈 2，因此有一个隐含的“DependsOn”。但在这种情况下，子模板 2 不依赖于子模板 1。相反，它依赖于任何满足其输入参数的东西（可以是父堆栈或其他东西）。