add support for AWS ELB healthcheck probe

Signed-off-by: Manuel Boillod <[email protected]>

CHANGELOG.md

@@ -27,6 +27,8 @@ This changelog keeps track of work items that have been completed and are ready
 - **General**: Support setting multiple TLS certs for different domains on the interceptor proxy ([#1116](https://github.com/kedacore/http-add-on/issues/1116))
 - **General**: TODO ([#TODO](https://github.com/kedacore/http-add-on/issues/TODO))
 
+- **Interceptor**: Add support for for AWS ELB healthcheck probe ([#1198](https://github.com/kedacore/http-add-on/issues/1198))
+
 ### Improvements
 
 - **General**: TODO ([#TODO](https://github.com/kedacore/http-add-on/issues/TODO))

interceptor/middleware/routing.go

@@ -17,6 +17,7 @@ import (
 var (
 	kubernetesProbeUserAgent = regexp.MustCompile(`(^|\s)kube-probe/`)
 	googleHCUserAgent        = regexp.MustCompile(`(^|\s)GoogleHC/`)
+	awsELBserAgent           = regexp.MustCompile(`(^|\s)ELB-HealthChecker/`)
 )
 
 type Routing struct {
@@ -112,5 +113,5 @@ func (rm *Routing) streamFromHTTPSO(ctx context.Context, httpso *httpv1alpha1.HT
 func (rm *Routing) isProbe(r *http.Request) bool {
 	ua := r.UserAgent()
 
-	return kubernetesProbeUserAgent.Match([]byte(ua)) || googleHCUserAgent.Match([]byte(ua))
+	return kubernetesProbeUserAgent.Match([]byte(ua)) || googleHCUserAgent.Match([]byte(ua)) || awsELBserAgent.Match([]byte(ua))
 }

interceptor/middleware/routing_test.go

@@ -304,7 +304,19 @@ var _ = Describe("RoutingMiddleware", func() {
 			Expect(b).To(BeTrue())
 		})
 
-		It("returns false if the request is not from kube-probe or GoogleHC", func() {
+		It("returns true if the request is from AWS ELB", func() {
+			const (
+				uaVal = "Go-http-client/1.1 ELB-HealthChecker/2.0 (linux/amd64) kubernetes/4c94112"
+			)
+
+			r.Header.Set(uaKey, uaVal)
+
+			var rm Routing
+			b := rm.isProbe(r)
+			Expect(b).To(BeTrue())
+		})
+
+		It("returns false if the request is not from kube-probe or GoogleHC or ELB-HealthChecker", func() {
 			const (
 				uaVal = "Go-http-client/1.1 kubectl/v1.27.1 (linux/amd64) kubernetes/4c94112"
 			)