AWS Cloudformation-如何依赖另一个嵌套堆栈中的DependsOn资源 [英] AWS Cloudformation - how to DependsOn resource from another nested stack

问题描述

我有一个带有嵌套堆栈的CF父模板.我想做的是在一个嵌套堆栈中设置DependsOn属性，以检查另一个嵌套堆栈中的资源.

I have a CF parent template with nested stacks in it. What I'm trying to do is set DependsOn attribute in one of the nested stacks, to check for the resource from another nested stack.

这是我的设置:

  RDS:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: https://cf-app-stack.s3.eu-west-2.amazonaws.com/infrastructure/rds.yaml
      Parameters:
        EnvironmentName: !Ref AWS::StackName
        DBVPCSecurityGroup: !GetAtt SecurityGroups.Outputs.DBVPCSecurityGroup
        PrivateSubnet1: !GetAtt VPC.Outputs.PrivateSubnet1
        PrivateSubnet2: !GetAtt VPC.Outputs.PrivateSubnet2

  ECS:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: https://cf-app-stack.s3.eu-west-2.amazonaws.com/infrastructure/ecs-cluster.yaml
      Parameters:
        EnvironmentName: !Ref AWS::StackName
        MasterDB: !GetAtt RDS.Outputs.MasterDB
        InstanceType: t2.micro
        ClusterSize: 1
        VPC: !GetAtt VPC.Outputs.VPC
        SecurityGroup: !GetAtt SecurityGroups.Outputs.ECSHostSecurityGroup
        Subnets: !GetAtt VPC.Outputs.PrivateSubnets

嵌套的RDS堆栈:(导出数据库资源引用)

 MasterDB:
    Type: AWS::RDS::DBInstance
    Properties:
      DBSnapshotIdentifier: arn:aws:rds:eu-west-2:731152906121:snapshot:db-starter-image
      AllocatedStorage: !Ref DBAllocatedStorage
      DBInstanceClass: !Ref DBInstanceClass
      Engine: MySQL
      # Some DB instance properties aren't valid when you restore from a snapshot, such as the MasterUsername and MasterUserPassword properties. 
      #MasterUsername: !Ref DBUser
      #MasterUserPassword: !Ref DBPassword
      MultiAZ: !Ref 'MultiAZ'
      Tags:
      - Key: Name
        Value: !Sub ${EnvironmentName}-Database
      DBSubnetGroupName: !Ref myDBSubnetGroup
      VPCSecurityGroups: [ !Ref DBVPCSecurityGroup ]
    DeletionPolicy: Snapshot

Outputs:
  MasterDB:
    Description: A reference to the created DB
    Value: MasterDB

嵌套ECS堆栈:(我希望这个依赖于上述嵌套堆栈中的RDS实例)

Parameters:
  MasterDB:
    Description: A reference to the created DB
    Type: String

Resources:
  ECSCluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: !Ref EnvironmentName

  ECSAutoScalingGroup:
    DependsOn: [ECSCluster, !Ref MasterDB]
    Type: AWS::AutoScaling::AutoScalingGroup
    Properties:
      VPCZoneIdentifier: !Ref Subnets
      LaunchConfigurationName: !Ref ECSLaunchConfiguration
      MinSize: !Ref ClusterSize
      MaxSize: !Ref ClusterSize
      DesiredCapacity: !Ref ClusterSize
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} ECS host
          PropagateAtLaunch: true

请参见上面的代码中的"DependsOn:[ECSCluster，！Ref MasterDB]".我做错了吗?我尝试了其他变体来满足DependsOn，但到目前为止还算不上运气.

See "DependsOn: [ECSCluster, !Ref MasterDB]" in the above code. Am I doing this wrong? I tried other variations trying to satisfy DependsOn but so far no luck.

推荐答案

对于特定的场景，您实际上并不需要使用DependsOn，而且我认为该属性甚至不支持引用堆栈外的资源.原因是为了引用嵌套堆栈中的值，需要从另一个堆栈的Output属性中传递该值.只需将Output参数传递到嵌套堆栈，即可使该堆栈依赖于它从中导出的其他嵌套堆栈-仅此一项即可实现您的目标.

You don't really need to use DependsOn for you specific Scenario and I think this attribute doesn't even support referring to resources outside of the stack. The reason is that in order to reference a value in a nested stack, it needs to be passed in from Output attributes from another stack. And just passing an Output parameter to a nested stack makes this stack dependent on the other nested stack it was exported from - and that alone achieves your goal.

获取您的代码，

嵌套的ECS堆栈:

Parameters:

  MasterDB:
    Description: Make this stack dependent on RDS resource
    Type: String

这就是您需要做的，甚至不需要在嵌套堆栈中的任何位置使用该参数.

That's all you need to do, the parameter does not even need to be used anywhere in the nested stack.

因此，如果一个堆栈依赖于另一个堆栈，那么它们只能一个接一个地执行并自上而下完成.

So if one stack is dependent on another, they can only be executed and completed top to bottom, one after another.

例如，如果:

堆栈A:接受堆栈B的Attr1输出

Stack A: accepts Attr1 Output from stack B

和

堆栈B:接受堆栈A的Attr2输出

Stack B: accepts Attr2 Output from stack A

以上内容将始终失败，因为无论首先执行哪个堆栈，依赖于其的Attr参数都无法准备.

The above will always fail, because regardless of which stack will be executed first, the Attr param it is dependent on will not be ready.

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