amazon-web-services - Cloudformation 嵌套堆栈模板子对子参数的 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 以及引用它的另一个子模板 EC2InstanceResourcesStack。我确保为后一个子模板添加 DependsOn 子句，但我仍然收到错误。

这是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，其中上述输出被传递到 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

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

Answer 1

您无法直接从一个模板引用另一个模板中的资源(通过 Ref)，即使它们是父子模板或同级模板。资源是特定于堆栈的，除非通过 Output 部分显式导出它们。

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，然后导入子模板 2 中的这些值。

例如:

在“源”模板中:

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

然后将值导入“消费”模板中:

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

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

一个缺点是你不能“DependsOn”。而且，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(即直到父模板)，然后从从父级到另一个子级。

因此，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 个子堆栈在父堆栈中 Hook 在一起:

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

在这种情况下，在子堆栈 1 准备好并输出其值之前，不会创建子堆栈 2，因此存在隐含的“DependsOn”。但在本例中，子模板 2 不依赖于子模板 1。相反，它依赖于满足其输入参数的任何内容(可以是父堆栈或其他参数)。