08. Adding Target Groups and Listeners

ND9991 C2 L04 A05.2 No Title

The following is the required syntax for TargetGroup:

Type: AWS::ElasticLoadBalancingV2::TargetGroup
Properties: 
  HealthCheckEnabled: Boolean
  HealthCheckIntervalSeconds: Integer
  HealthCheckPath: String
  HealthCheckPort: String
  HealthCheckProtocol: String
  HealthCheckTimeoutSeconds: Integer
  HealthyThresholdCount: Integer
  Matcher: 
    Matcher
  Name: String
  Port: Integer
  Protocol: String
  Tags: 
    - Tag
  TargetGroupAttributes: 
    - TargetGroupAttribute
  TargetType: String
  Targets: 
    - TargetDescription
  UnhealthyThresholdCount: Integer
  VpcId: String


Health Checks are the requests your Application Load Balancersends to its registered targets. These periodic requests test the status of these targets. You can see us defining our Health Check properties in the example below:

 WebAppTargetGroup:
    Type: AWS::ElasticLoadBalancingV2::TargetGroup
    Properties:
      HealthCheckIntervalSeconds: 35
      HealthCheckPath: /
      HealthCheckProtocol: HTTP
      HealthCheckTimeoutSeconds: 30
      HealthyThresholdCount: 2
      Port: 80
      Protocol: HTTP
      UnhealthyThresholdCount: 5
      VpcId: 
        Fn::ImportValue:
          Fn::Sub: "${EnvironmentName}-VPCID"

In the above example we specify the following:

  • The port where our targets receive traffic - Port: 80
  • The protocol the load balancer uses when performing health checks on targets - HealthCheckProtocol: HTTP
  • The time it takes to determine a non-responsive target is unhealthy - HealthCheckIntervalSeconds: 35
  • The number of healthy/unhealthy checks required to change the health status - HealthyThresholdCount: 2 UnhealthyThresholdCount: 5

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