example.yml

AWSTemplateFormatVersion: 2010-09-09
Description: Combined template for ALB Dynamic Priority testing

Parameters:
  LambdaImageUri:
    Type: String
    Description: The URI of the Lambda function image

Resources:
  # VPC and Networking Resources
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: 10.0.0.0/16
      EnableDnsSupport: true
      EnableDnsHostnames: true
      Tags:
        - Key: Name
          Value: TestVPC

  InternetGateway:
    Type: AWS::EC2::InternetGateway
    Properties:
      Tags:
        - Key: Name
          Value: TestIGW

  InternetGatewayAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !Ref VPC
      InternetGatewayId: !Ref InternetGateway

  PublicSubnet1:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [0, !GetAZs ""]
      CidrBlock: 10.0.1.0/24
      MapPublicIpOnLaunch: true
      Tags:
        - Key: Name
          Value: TestPublicSubnet1

  PublicSubnet2:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [1, !GetAZs ""]
      CidrBlock: 10.0.2.0/24
      MapPublicIpOnLaunch: true
      Tags:
        - Key: Name
          Value: TestPublicSubnet2

  PublicRouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
      Tags:
        - Key: Name
          Value: TestPublicRouteTable

  DefaultPublicRoute:
    Type: AWS::EC2::Route
    DependsOn: InternetGatewayAttachment
    Properties:
      RouteTableId: !Ref PublicRouteTable
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref InternetGateway

  PublicSubnet1RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnet1
      RouteTableId: !Ref PublicRouteTable

  PublicSubnet2RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnet2
      RouteTableId: !Ref PublicRouteTable

  LoadBalancerSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Security group for the load balancer
      VpcId: !Ref VPC
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: 0.0.0.0/0
        - IpProtocol: tcp
          FromPort: 443
          ToPort: 443
          CidrIp: 0.0.0.0/0

  ApplicationLoadBalancer:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Properties:
      Name: test-alb
      Scheme: internet-facing
      Type: application
      Subnets:
        - !Ref PublicSubnet1
        - !Ref PublicSubnet2
      SecurityGroups:
        - !Ref LoadBalancerSecurityGroup
      IpAddressType: ipv4

  HttpListener:
    Type: AWS::ElasticLoadBalancingV2::Listener
    Properties:
      DefaultActions:
        - Type: fixed-response
          FixedResponseConfig:
            ContentType: text/plain
            MessageBody: Default Response
            StatusCode: 200
      LoadBalancerArn: !Ref ApplicationLoadBalancer
      Port: 80
      Protocol: HTTP

  # Dynamic Priority Resources
  ListenerRuleAllocation:
    Type: Custom::ListenerRuleAllocation
    Properties:
      ServiceToken: !GetAtt ListenerRuleAllocationLambda.Arn
      ListenerArn: !Ref HttpListener
      PriorityCount: 2

  ListenerRule0:
    Type: AWS::ElasticLoadBalancingV2::ListenerRule
    Properties:
      Actions:
        - Type: fixed-response
          FixedResponseConfig:
            ContentType: text/plain
            MessageBody: Hello World
            StatusCode: 200
      Conditions:
        - Field: path-pattern
          Values:
            - /0
      ListenerArn: !Ref HttpListener
      Priority: !Select
        - 0
        - !Split
          - ","
          - !GetAtt ListenerRuleAllocation.Priorities

  ListenerRule1:
    Type: AWS::ElasticLoadBalancingV2::ListenerRule
    Properties:
      Actions:
        - Type: fixed-response
          FixedResponseConfig:
            ContentType: text/plain
            MessageBody: Hello World
            StatusCode: 200
      Conditions:
        - Field: path-pattern
          Values:
            - /1
      ListenerArn: !Ref HttpListener
      Priority: !Select
        - 1
        - !Split
          - ","
          - !GetAtt ListenerRuleAllocation.Priorities

  ListenerRuleCustomResourceLambdaRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      Policies:
        - PolicyName: DescribeRulesPolicy
          PolicyDocument:
            Statement:
              - Effect: Allow
                Action: elasticloadbalancing:DescribeRules
                Resource: "*"
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

  ListenerRuleAllocationLambda:
    Type: AWS::Lambda::Function
    Properties:
      Role: !GetAtt ListenerRuleCustomResourceLambdaRole.Arn
      Timeout: 30
      PackageType: Image
      Code:
        ImageUri: !Ref LambdaImageUri

Outputs:
  LoadBalancerDNS:
    Description: DNS name of the load balancer
    Value: !GetAtt ApplicationLoadBalancer.DNSName

  HttpListenerArn:
    Description: ARN of the HTTP listener
    Value: !Ref HttpListener