Copilot deploy fails when creating a load balancer listener to route HTTP traffic

It sounds like you're experiencing an issue with creating a load balancer listener during your Copilot deployment. This problem can occur due to several reasons:

1. Security Group Configuration: Ensure that the security group associated with your load balancer allows inbound traffic on both HTTP (port 80) and HTTPS (port 443). Check for any conflicting rules or missing outbound rules.

2. Listener Configuration: Verify that the HTTP listener on port 80 is properly configured. You may need to create a rule to redirect HTTP traffic to HTTPS or forward it to the appropriate target group.

3. Target Group Health: Check that the target group associated with your listener is correctly configured and has healthy targets. Verify the health check settings and ensure the targets are receiving traffic.

4. Network Configuration: Make sure your VPC, subnets, and network settings are correctly configured to allow traffic to flow to and from your load balancer.

5. IAM Permissions: Ensure that the IAM role used by Copilot has sufficient permissions to create and modify load balancer resources.

6. DNS Configuration: If you're using a custom domain, verify that your DNS settings correctly point to your load balancer's DNS name.

To troubleshoot:

1. Check the Copilot logs for any specific error messages.

2. Verify the load balancer configuration in the EC2 console.

3. Use the AWS CLI to test creating a listener manually:

   aws elb create-load-balancer-listeners --load-balancer-name your-load-balancer-name --listeners "Protocol=HTTP,LoadBalancerPort=80,InstanceProtocol=HTTP,InstancePort=80"

4. Enable access logs for your load balancer to get more detailed information about the requests and how they're being processed.

If the issue persists after checking these items, you may need to contact AWS support for further assistance, as there could be an underlying issue with the load balancer or network configuration that requires deeper investigation.
Sources
New Load Balancer Target Group Rule not working | AWS re:Post
Set up a load balancer, target groups, and listeners for CodeDeploy Amazon ECS deployments - AWS CodeDeploy
Application load balancer works for https not http. | AWS re:Post
Use CreateLoadBalancerListeners with a CLI - AWS SDK Code Examples