keep LB addons' settings unchanged unless explicitly specified (#3800)

add UTs for related components

docs/guide/ingress/annotations.md

@@ -907,35 +907,53 @@ In addition, you can use annotations to specify additional tags
 
 ## Addons
 
-!!!note
-    If waf-acl-arn is specified via the ingress annotations, the controller will make sure the waf-acl is associated to the provisioned ALB with the ingress. 
-    If there is not such annotation, the controller will make sure no waf-acl is associated, so it may remove the existing waf-acl on the ALB provisioned. 
-    If users do not want the controller to manage the waf-acl on the ALBs, they can disable the feature by setting controller command line flags `--enable-waf=false` or `--enable-wafv2=false`
-
-- <a name="waf-acl-id">`alb.ingress.kubernetes.io/waf-acl-id`</a> specifies the identifier for the Amazon WAF web ACL.
+- <a name="waf-acl-id">`alb.ingress.kubernetes.io/waf-acl-id`</a> specifies the identifier for the Amazon WAF Classic web ACL.
 
     !!!warning ""
-        Only Regional WAF is supported.
+        Only Regional WAF Classic is supported.
+
+    !!!note ""
+        When this annotation is absent or empty, the controller will keep LoadBalancer WAF Classic settings unchanged.
+        To disable WAF Classic, explicitly set the annotation value to 'none'.
 
     !!!example
-        ```alb.ingress.kubernetes.io/waf-acl-id: 499e8b99-6671-4614-a86d-adb1810b7fbe
-        ```
+        - enable WAF Classic
+            ```alb.ingress.kubernetes.io/waf-acl-id: 499e8b99-6671-4614-a86d-adb1810b7fbe
+            ```
+        - disable WAF Classic
+            ```alb.ingress.kubernetes.io/waf-acl-id: none
+            ```
 
 - <a name="wafv2-acl-arn">`alb.ingress.kubernetes.io/wafv2-acl-arn`</a> specifies ARN for the Amazon WAFv2 web ACL.
 
     !!!warning ""
         Only Regional WAFv2 is supported.
 
+    !!!note ""
+        When this annotation is absent or empty, the controller will keep LoadBalancer WAFv2 settings unchanged.
+        To disable WAFv2, explicitly set the annotation value to 'none'.
+
     !!!tip ""
         To get the WAFv2 Web ACL ARN from the Console, click the gear icon in the upper right and enable the ARN column.
 
     !!!example
-        ```alb.ingress.kubernetes.io/wafv2-acl-arn: arn:aws:wafv2:us-west-2:xxxxx:regional/webacl/xxxxxxx/3ab78708-85b0-49d3-b4e1-7a9615a6613b
-        ```
-
+        - enable WAFv2
+            ```alb.ingress.kubernetes.io/wafv2-acl-arn: arn:aws:wafv2:us-west-2:xxxxx:regional/webacl/xxxxxxx/3ab78708-85b0-49d3-b4e1-7a9615a6613b
+            ```
+        - disable WAFV2
+            ```alb.ingress.kubernetes.io/wafv2-acl-arn: none
+            ```
+
 - <a name="shield-advanced-protection">`alb.ingress.kubernetes.io/shield-advanced-protection`</a> turns on / off the AWS Shield Advanced protection for the load balancer.
 
-    !!!example
-        ```alb.ingress.kubernetes.io/shield-advanced-protection: 'true'
-        ```
+    !!!note ""
+        When this annotation is absent, the controller will keep LoadBalancer shield protection settings unchanged.
+        To disable shield protection, explicitly set the annotation value to 'false'.
 
+    !!!example
+        - enable shield protection
+            ```alb.ingress.kubernetes.io/shield-advanced-protection: 'true'
+            ```
+        - disable shield protection
+            ```alb.ingress.kubernetes.io/shield-advanced-protection: 'false'
+            ```

pkg/deploy/shield/protection_synthesizer.go

@@ -2,11 +2,11 @@ package shield
 
 import (
 	"context"
+	"fmt"
 	"github.com/go-logr/logr"
 	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"sigs.k8s.io/aws-load-balancer-controller/pkg/model/core"
-	elbv2model "sigs.k8s.io/aws-load-balancer-controller/pkg/model/elbv2"
 	shieldmodel "sigs.k8s.io/aws-load-balancer-controller/pkg/model/shield"
 )
 
@@ -32,25 +32,18 @@ type protectionSynthesizer struct {
 
 func (s *protectionSynthesizer) Synthesize(ctx context.Context) error {
 	var resProtections []*shieldmodel.Protection
-	s.stack.ListResources(&resProtections)
+	if err := s.stack.ListResources(&resProtections); err != nil {
+		return fmt.Errorf("[should never happen] failed to list resources: %w", err)
+	}
+	if len(resProtections) == 0 {
+		return nil
+	}
 	resProtectionsByResARN, err := mapResProtectionByResourceARN(resProtections)
 	if err != nil {
 		return err
 	}
-
-	var resLBs []*elbv2model.LoadBalancer
-	s.stack.ListResources(&resLBs)
-	for _, resLB := range resLBs {
-		// shield protection can only be associated with ALB for now.
-		if resLB.Spec.Type != elbv2model.LoadBalancerTypeApplication {
-			continue
-		}
-		lbARN, err := resLB.LoadBalancerARN().Resolve(ctx)
-		if err != nil {
-			return err
-		}
-		resProtections := resProtectionsByResARN[lbARN]
-		if err := s.synthesizeProtectionsOnLB(ctx, lbARN, resProtections); err != nil {
+	for resARN, protections := range resProtectionsByResARN {
+		if err := s.synthesizeProtectionsOnLB(ctx, resARN, protections); err != nil {
 			return err
 		}
 	}
@@ -63,18 +56,13 @@ func (s *protectionSynthesizer) PostSynthesize(ctx context.Context) error {
 }
 
 func (s *protectionSynthesizer) synthesizeProtectionsOnLB(ctx context.Context, lbARN string, resProtections []*shieldmodel.Protection) error {
-	if len(resProtections) > 1 {
-		return errors.Errorf("[should never happen] multiple shield protection desired on LoadBalancer: %v", lbARN)
-	}
-
-	enableProtection := false
-	if len(resProtections) == 1 {
-		enableProtection = true
+	if len(resProtections) != 1 {
+		return errors.Errorf("[should never happen] should be exactly one shield protection desired on LoadBalancer: %v", lbARN)
 	}
-
+	enableProtection := resProtections[0].Spec.Enabled
 	protectionInfo, err := s.protectionManager.GetProtection(ctx, lbARN)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "failed to get shield protection on LoadBalancer")
 	}
 	switch {
 	case !enableProtection && protectionInfo != nil: