How to specify source security group Id in AWS CDK?

Question

Hi I am working on AWS CDK. I am writing security group templates. I am able to write it in Cloud formation. Now I am writing it in AWS CDK. I dint get any example for including source security group. Below is my cloud formation template wrote earlier.

Resources:
  MerchWebServicesSecurityGroup:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      Tags:
        - Key: "Name"
          Value: !Ref "AWS::StackName"
      GroupDescription: "EC2 Services Security Group"
      VpcId:
        Fn::ImportValue: "infra-vpc-base::VpcId"
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: "80"
          ToPort: "80"
          SourceSecurityGroupId: !Ref MerchWebServicesLoadBalancerSecurityGroup
        - IpProtocol: tcp
          FromPort: "443"
          ToPort: "443"
          SourceSecurityGroupId: !Ref MerchWebServicesLoadBalancerSecurityGroup
        - IpProtocol: tcp
          FromPort: 31000
          ToPort: 65535
          SourceSecurityGroupId: !Ref MerchWebServicesLoadBalancerSecurityGroup

  MerchWebServicesLoadBalancerSecurityGroup:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      Tags:
        -
          Key: "Name"
          Value: !Ref "AWS::StackName"
      GroupDescription: "MerchWebServices ALB Group"
      VpcId:
        Fn::ImportValue: "infra-vpc-base::VpcId"
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: '172.30.1.0/15'

In the above template I have created SG MerchWebServicesSecurityGroup and I have specified SourceSecurityGroupId as another SG MerchWebServicesLoadBalancerSecurityGroup.

        #create SG MerchWebServicesLoadBalancerSecurityGroup
        mws_vpc_sg_alb  = ec2.SecurityGroup(self,"MerchWebServicesLoadBalancerSecurityGroup",
        description = "MerchWebServices ALB Group",
        security_group_name = "MerchWebServicesLoadBalancerSecurityGroup",
        vpc= vpc);

        mws_vpc_sg_alb.add_ingress_rule(peer = ec2.Peer.ipv4('172.30.0.0/15'), connection = ec2.Port.tcp(80));

        #create SG MerchWebServicesSecurityGroup
        mws_vpc_sg = ec2.SecurityGroup(self,"MerchWebServicesSecurityGroup",
        description="EC2 Services Security Group",
        security_group_name="MerchWebServicesSecurityGroup",
        vpc = vpc);
        mws_vpc_sg.add_ingress_rule(peer = ec2.Peer.ipv4(mws_vpc_sg_alb), connection = ec2.Port.tcp(80));

In the above code I am trying to create SG MerchWebServicesSecurityGroup and below I am adding ingress rules

mws_vpc_sg.add_ingress_rule(peer = ec2.Peer.ipv4(mws_vpc_sg_alb), connection = ec2.Port.tcp(80));

Here instead of specifying Cidr block I want to specify SourceSecurityGroupId. In AWS CDK I am not sure how to use Ref and include SourceSecurityGroupId. Can someone help me to complete this? Any help would be appreciated. Thanks

Answer 1

ec2.SecurityGroup implements IPeer interface, therefore the security group itself can be used as a peer.

mws_vpc_sg_alb.add_ingress_rule(
     peer=mws_vpc_sg_alb,
     connection=ec2.Port.tcp(80),
     description='ALB access'
)