Create a self-signed certificate for service.example.com. Import the certificate into AWS Certificate Manager (ACM). Configure CloudFront to use this imported SSL/TLS certificate. Change the default behavior to redirect HTTP to HTTPS.

Create a certificate for service.example.com by using AWS Certificate Manager (ACM). Configure CloudFront to use this custom SSL/TLS certificate. Change the default behavior to redirect HTTP to HTTPS.

Create a certificate with any domain name by using AWS Certificate Manager (ACM) for the EC2 instances. Configure the backend to use this certificate for its HTTPS listener. Specify the instance target type during the creation of a new target group that uses the HTTPS protocol for its targets. Attach the existing Auto Scaling group to this new target group.

Create a public certificate from a third-party certificate provider with any domain name for the EC2 instances. Configure the backend to use this certificate for its HTTPS listener. Specify the instance target type during the creation of a new target group that uses the HTTPS protocol for its targets. Attach the existing Auto Scaling group to this new target group.

Create a certificate for service-alb.example.com by using AWS Certificate Manager (ACM). On the ALB add a new HTTPS listener that uses the new target group and the service-alb.example.com ACM certificate. Modify the CloudFront origin to use the HTTPS protocol only. Delete the HTTP listener on the ALB.