CloudFormation !Select with !Split function with load balancer arn

Question

我正在尝试使用 cloudformation 模板为网络 ELB 创建 cloudwatch 警报。我正在使用 Select 函数与拆分函数的组合来获取需要的元素。

NLB：- arn:aws:elasticloadbalancing:eu-west-1:123456:loadbalancer/net/dev-nlb-3HGD5SO64D/7GL51FD3

NLBTargetGroup:- arn:aws:elasticloadbalancing:eu-west-1:123456:targetgroup/dev-nlb-2A6W3JC4R/9DH34SJY

  Alarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      ActionsEnabled: True
      AlarmDescription: test alarm
      ComparisonOperator:  GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: LoadBalancer
          Value: !Select ["5", !Split [":", !Ref NLB]]
        - Name: TargetGroup
          Value: !Select ["5", !Split [":", !Ref NLBTargetGroup]]
      EvaluationPeriods: 1
      MetricName: HealthyHostCount
      Namespace: AWS/NetworkELB
      AlarmActions:
        - arn:aws:sns:eu-west-1:123456:TestSNS
      OKActions:
        - arn:aws:sns:eu-west-1:123456:TestSNS
      Period: 60
      Statistic: Average
      Threshold: 2.0
      TreatMissingData: missing

使用上述配置，我可以将“TargetGroup”的 select 值设置为“targetgroup/dev-nlb-2A6W3JC4R/9DH34SJY”，但“LoadBalancer”的值将设置为“loadbalancer/net/dev-nlb-3HGD5SO64D/7GL51FD3”。我的目标是只获得“net/dev-nlb-3HGD5SO64D/7GL51FD3”

我怎样才能做到这一点？

Answer 1

如果这些资源与您的警报在同一个 CloudFormation 堆栈中，您实际上可以使用以下功能来获取这两种资源的名称：

!GetAtt: NLB.LoadBalancerFullName
!GetAtt: NLBTargetGroup.TargetGroupFullName

对于您的堆栈，这将变为

  Alarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      ActionsEnabled: True
      AlarmDescription: test alarm
      ComparisonOperator:  GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: LoadBalancer
          Value: NLB.LoadBalancerFullName
        - Name: TargetGroup
          Value: NLBTargetGroup.TargetGroupFullName
      EvaluationPeriods: 1
      MetricName: HealthyHostCount
      Namespace: AWS/NetworkELB
      AlarmActions:
        - arn:aws:sns:eu-west-1:123456:TestSNS
      OKActions:
        - arn:aws:sns:eu-west-1:123456:TestSNS
      Period: 60
      Statistic: Average
      Threshold: 2.0
      TreatMissingData: missing

如果这是嵌套堆栈的一部分，您当然也可以将这些值用作 output。

否则，如果它们是单独堆栈的一部分（而不是嵌套堆栈），而您只是将这些值复制到（或从导出中引用），您将需要执行多次拆分以检索您要获取的信息正在寻找。

Answer 2

你可以使用 for NLB:

!GetAtt YourNLB.LoadBalancerFullName

和 target group:

!GetAtt YourTG.TargetGroupFullName

因此你可以这样做：

      Dimensions:
        - Name: LoadBalancer
          Value: !GetAtt YourNLB.LoadBalancerFullName
        - Name: TargetGroup
          Value: !GetAtt YourTG.TargetGroupFullName

如果您确实需要拆分字符串，对于 NLB，您的 Split-Join 组合将是：

 Value: !Join
      - '/'
      - - !Select [1, !Split [ '/', !Select ["5", !Split [":", !Ref NLB]]]]
        - !Select [2, !Split [ '/', !Select ["5", !Split [":", !Ref NLB]]]]
        - !Select [3, !Split [ '/', !Select ["5", !Split [":", !Ref NLB]]]]

对于目标组：

  Value: !Join
    - '/'
    - - !Select [1, !Split [ '/', !Select ["5", !Split [":", !Ref NLBTargetGroup]]]]
      - !Select [2, !Split [ '/', !Select ["5", !Split [":", !Ref NLBTargetGroup]]]]

CloudFormation !Select with !Split function with load balancer arn

CloudFormation !Select with !Split function with load balancer arn

nlb

amazon-web-services

amazon-cloudformation

amazon-cloudwatch

aws-elb