middleware.yaml

AWSTemplateFormatVersion: "2010-09-09"
Description: Middleware template

Parameters:
  Environment:
    Type: String
    Default: test
    AllowedValues: [ "test", "prod" ]
  ImageId:
    Type: AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>
    Default: '/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2'
  KeyName:
    Type: AWS::EC2::KeyPair::KeyName
    Default: mykey

Resources:

# Target Group for ASG and ELB, Middleware Instance SG
  MiddlewareTg:
    Type: "AWS::ElasticLoadBalancingV2::TargetGroup"
    Properties:
      Port: 80
      Protocol: HTTP
      VpcId: !ImportValue VpcId
      Tags:
        - Key: Env
          Value: !Ref Environment
        - Key: Name
          Value: !Join [ "-", [ !Ref Environment, !Ref "AWS::StackName", "lb-tg" ] ]

  MiddlewareInstanceSg:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      GroupDescription: Middleware Instance SG
      SecurityGroupIngress:
        - IpProtocol: tcp
          SourceSecurityGroupId: !Ref MiddlewareLbSg
          FromPort: 80
          ToPort: 80
      VpcId: !ImportValue VpcId
      Tags:
        - Key: Env
          Value: !Ref Environment
        - Key: Name
          Value: !Join [ "-", [ !Ref Environment, !Ref "AWS::StackName", "inst-sg" ] ]

# Load balancer, listener, security group
  MiddlewareLoadBalancer:
    Type: "AWS::ElasticLoadBalancingV2::LoadBalancer"   
    Properties:
      Type: application
      Subnets:
        - !ImportValue MiddlewareSubnet1Id
        - !ImportValue MiddlewareSubnet2Id
        - !ImportValue MiddlewareSubnet3Id
      Scheme: internal
      SecurityGroups:
        - !Ref MiddlewareLbSg
      Tags:
        - Key: Env
          Value: !Ref Environment
        - Key: Name
          Value: !Join [ "-", [ !Ref Environment, !Ref "AWS::StackName", "lb" ] ]

  MiddlewareLbListener:
    Type: "AWS::ElasticLoadBalancingV2::Listener"   
    Properties:
      Port: 80
      Protocol: HTTP
      DefaultActions:
        - Type: "forward"
          TargetGroupArn: !Ref MiddlewareTg

  MiddlewareLbSg:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      GroupDescription: LoadBalancer Security Group
      SecurityGroupIngress:
        - IpProtocol: tcp
          SourceSecurityGroupId: !ImportValue WebInstanceSg
          FromPort: 80
          ToPort: 80
      VpcId: !ImportValue VpcId
      Tags:
        - Key: Env
          Value: !Ref Environment
        - Key: Name
          Value: !Join [ "-", [ !Ref Environment, !Ref "AWS::StackName", "lb-sg" ] ]

# Autoscaling group, launch template

  MiddlewareInstanceLaunchTemplate:
    Type: "AWS::EC2::LaunchTemplate"
    Properties:
      LaunchTemplateData:
        ImageId: !Ref ImageId
        InstanceType: t3.micro
        KeyName: !Ref KeyName
        SecurityGroupIds:
          - !Ref MiddlewareInstanceSg
        TagSpecifications:
          - ResourceType: instance
            Tags:
              - Key: Env
                Value: !Ref Environment
              - Key: Name
                Value: !Join [ "-", [ !Ref Environment, !Ref "AWS::StackName", "lt" ] ]

  MiddlewareAsg:
    DependsOn: MiddlewareLbListener
    Type: "AWS::AutoScaling::AutoScalingGroup"
    Properties:
      MaxSize: !Join [":", [ "{{resolve:ssm", !ImportValue MiddlewareMaxSizeParameter, "1}}"]]
      MinSize: !Join [":", [ "{{resolve:ssm", !ImportValue MiddlewareMinSizeParameter, "1}}"]]
      DesiredCapacity: !Join [":", [ "{{resolve:ssm", !ImportValue MiddlewareDesSizeParameter, "1}}"]]
      VPCZoneIdentifier:
        - !ImportValue MiddlewareSubnet1Id
        - !ImportValue MiddlewareSubnet2Id
        - !ImportValue MiddlewareSubnet3Id
      LaunchTemplate:
        LaunchTemplateId: !Ref MiddlewareInstanceLaunchTemplate
        Version: "1"
      TargetGroupARNs:
        - !Ref MiddlewareTg
      Tags:
        - Key: Env
          Value: !Ref Environment
          PropagateAtLaunch: True
        - Key: Name
          Value: !Join [ "-", [ !Ref Environment, !Ref "AWS::StackName", "asg" ] ]
          PropagateAtLaunch: True

Outputs:
  MiddlewareInstanceSg:
    Value: !Ref MiddlewareInstanceSg
    Export:
      Name: MiddlewareInstanceSg