ELB/TargetGroup/ASG attachment fixes

[rifelpet]

ref: #10134 (comment)

This addresses three issues:

• External TargetGroupARNs werent being attached to ASGs at creation-time with --target direct
• Kops was passing the name of the API ELB task to attach to the ASG rather than the resulting AWS LoadBalancerName which gets truncated and suffixed. This was resulting in AWS errors when creating the ASG, reporting that the ELB is not found.
• Subsequent update clusters were reporting changes because when Finding the LBs attached to the ASG, we couldn't tell which was the API ELB and which were external ELBs passed in through the InstanceGroupSpec. Find now looks for the API ELB to decide whether an ELB attached to the ASG should be the API ELB task or an external ELB task.

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[rifelpet]

@hakman can you test this commit out?

[hakman]

@hakman can you test this commit out?

No luck. Same thing.

[rifelpet]

@hakman did some troubleshooting and discovered that we used to be correctly passing the AWS LoadBalancerName when attaching LBs to ASGs. the LoadBalancerName is the truncated name we pass in CreateLoadBalancer and gets a random hashed suffix.

kops/upup/pkg/fi/cloudup/awstasks/load_balancer_attachment.go

Lines 64 to 66 in f3ea21a

	if aws.StringValue(e.LoadBalancer.LoadBalancerName) == "" {
	return nil, fmt.Errorf("LoadBalancer did not have LoadBalancerName set")
	}

#9794 changed that such that we now try to pass the original Name (the kops task name) to the Attach call which fails.

kops/pkg/model/awsmodel/autoscalinggroup.go

Lines 356 to 358 in b7f66a6

	if b.UseLoadBalancerForAPI() && ig.Spec.Role == kops.InstanceGroupRoleMaster {
	t.LoadBalancers = append(t.LoadBalancers, b.LinkToELB("api"))
	}

kops/pkg/model/names.go

Lines 88 to 91 in b7f66a6

	func (b *KopsModelContext) LinkToELB(prefix string) *awstasks.LoadBalancer {
	name := b.ELBName(prefix)
	return &awstasks.LoadBalancer{Name: &name}
	}

kops/upup/pkg/fi/cloudup/awstasks/autoscalinggroup.go

Lines 279 to 281 in b7f66a6

	for _, k := range e.LoadBalancers {
	request.LoadBalancerNames = append(request.LoadBalancerNames, k.GetName())
	}

So we need to update the ASG task to try to use the LoadBalancerName field of the LB task, fetching it from AWS if we don't yet know it. External load balancers coming from the InstanceGroupSpec are the LoadBalancerName so we set that field when setting up the ASG task, but only the task name is known for the API load balancer so LinkToELB("api") only sets the Name field of the task, leaving LoadBalancerName blank. We then lookup the LoadBalancerName for the given Name, failing the ASG task if the LB doesn't yet exist.

My last commit in this PR aims to accomplish that.

[rifelpet]

/cc @rdrgmnzs

[hakman]

/lgtm

[rdrgmnzs]

/lgtm

Thanks for the fix @rifelpet and for catching the issue @hakman