Ignore changes reported by subsequent updates

Usually this is an "actual.Foo = e.Foo" one-liner but we don't know which LB attached to an ASG is the API ELB so it's a bit more complicated

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

@@ -32,6 +32,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/autoscaling"
 	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/aws/aws-sdk-go/service/elb"
 	"k8s.io/klog/v2"
 )
 
@@ -124,6 +125,39 @@ func (e *AutoscalingGroup) Find(c *fi.Context) (*AutoscalingGroup, error) {
 		})
 	}
 
+	{
+		// pkg/model/awsmodel/autoscalinggroup.go doesn't know the LoadBalancerName of the API ELB task that it sets up
+		// it only knows the LoadBalancerName of external load balancers passed through the InstanceGroupSpec
+		// We lookup the LoadBalancerName for LoadBalancer tasks that don't have it set, in order to attach the LB to the ASG
+		// To prevent spurious changes being reported, we need to regenerate those tasks to be identical when Finding them from AWS
+		// Because we don't know whether any given LoadBalancerName attached to an ASG is the API ELB task or not,
+		// we have to find the API ELB task, lookup its LoadBalancerName, and then compare that to the list of attached LoadBalancers
+		// in order to make the tasks returned from Find identical to the ones generated by the model.
+		var apiLBTask *LoadBalancer
+		var apiLBDesc *elb.LoadBalancerDescription
+		for _, lb := range e.LoadBalancers {
+			// All external ELBs have their Shared field set to true. The API ELB does not.
+			// Note that Shared is set by the kops model rather than AWS tags.
+			if !fi.BoolValue(lb.Shared) {
+				apiLBTask = lb
+			}
+		}
+		if apiLBTask != nil && len(actual.LoadBalancers) > 0 {
+			apiLBDesc, err = FindLoadBalancerByNameTag(c.Cloud.(awsup.AWSCloud), fi.StringValue(apiLBTask.Name))
+			if err != nil {
+				return nil, err
+			}
+			if apiLBDesc != nil {
+				for i := 0; i < len(actual.LoadBalancers); i++ {
+					lb := actual.LoadBalancers[i]
+					if aws.StringValue(apiLBDesc.LoadBalancerName) == aws.StringValue(lb.Name) {
+						actual.LoadBalancers[i] = apiLBTask
+					}
+				}
+			}
+		}
+	}
+
 	for _, tg := range g.TargetGroupARNs {
 		actual.TargetGroups = append(actual.TargetGroups, &TargetGroup{ARN: aws.String(*tg)})
 	}