Can't register EC2 instance in ELB

Question

I'm trying to set up an AWS environment for the first time and have so far got a DNS entry pointing to a Classic ELB. I also have an EC2 instance running but I don't seem to be able to add the EC2 instance to the ELB in the UI. The documentation says that I can do this in the "Instances" tab in Load balancer screen but I don't have the tab at all. All I can see is Description | Listeners | Monitoring | Tags.

Does anyone have any ideas why the "Instances" tab night be missing from the UI?

Answer 1

There are now two different types of Elastic Load Balancer.

ELB/1.0, the original, is now called a "Classic" balancer.

ELB/2.0, the new version, is an "Application Load Balancer" (or "ALB").

They each have different features and capabilities.

One notable difference is that ALB doesn't simply route traffic to instances, it routes traffic to targets on instances, so (for example) you could pool multiple services on the same instance (e.g. port 8080, 8081, 8082) even though those requests all came into the balancer on port 80. And these targets are configured in virtual objects called target groups. So there are a couple of new abstraction layers, and this part of the provisioning workflow is much different. It's also provisioned using a different set of APIs.

Since the new Application Load Balancer is the default selection in the console wizard, it's easy to click past it, not realizing that you've selected something other than the classic ELB you might have been expecting, and that sounds like what occurred in this case.