From 6cedba4b54feff744ec5b0b94c89844adac9ee08 Mon Sep 17 00:00:00 2001
From: Dave Protasowski <dprotaso@gmail.com>
Date: Tue, 22 Nov 2022 12:44:19 -0500
Subject: [PATCH 1/2] fix nil pointer in the drainer when it's reset

---
 network/handlers/drain.go      |  2 +-
 network/handlers/drain_test.go | 41 ++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/network/handlers/drain.go b/network/handlers/drain.go
index 5eee2ea42e..3b2f28a077 100644
--- a/network/handlers/drain.go
+++ b/network/handlers/drain.go
@@ -196,7 +196,7 @@ func (d *Drainer) resetTimer() {
 
 	d.Lock()
 	defer d.Unlock()
-	if d.timer.Stop() {
+	if d.timer != nil && d.timer.Stop() {
 		d.timer.Reset(d.QuietPeriod)
 	}
 }
diff --git a/network/handlers/drain_test.go b/network/handlers/drain_test.go
index 082b8100d0..8e35eb944a 100644
--- a/network/handlers/drain_test.go
+++ b/network/handlers/drain_test.go
@@ -546,3 +546,44 @@ func TestReset(t *testing.T) {
 	// Calling reset after a drain should succeed
 	d.Reset()
 }
+
+// https://github.com/knative/pkg/issues/2642
+func TestResetWithActiveRequests(t *testing.T) {
+	d := Drainer{
+		QuietPeriod: 5 * time.Second,
+		Inner: http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
+			return
+		}),
+	}
+
+	trafficStopped := make(chan struct{})
+	trafficStarted := make(chan struct{})
+	drainStarted := make(chan struct{})
+	defer close(trafficStopped)
+
+	go func() {
+		r, _ := http.NewRequest("GET", "knative.dev", nil)
+		close(trafficStarted)
+		for {
+			select {
+			case <-trafficStopped:
+				return
+			default:
+				w := httptest.NewRecorder()
+				d.ServeHTTP(w, r)
+			}
+		}
+	}()
+
+	go func() {
+		<-trafficStarted
+		close(drainStarted)
+		d.Drain()
+	}()
+
+	<-drainStarted
+	d.Reset()
+
+	// We need requests to be active for a bit
+	time.Sleep(time.Second)
+}

From 1f75f966604576575f43a4ebc6c5abf6045ae468 Mon Sep 17 00:00:00 2001
From: dprotaso <dprotaso@gmail.com>
Date: Tue, 22 Nov 2022 13:20:20 -0500
Subject: [PATCH 2/2] fix linter

---
 network/handlers/drain_test.go | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/network/handlers/drain_test.go b/network/handlers/drain_test.go
index 8e35eb944a..88e4f07e57 100644
--- a/network/handlers/drain_test.go
+++ b/network/handlers/drain_test.go
@@ -551,9 +551,7 @@ func TestReset(t *testing.T) {
 func TestResetWithActiveRequests(t *testing.T) {
 	d := Drainer{
 		QuietPeriod: 5 * time.Second,
-		Inner: http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
-			return
-		}),
+		Inner:       http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}),
 	}
 
 	trafficStopped := make(chan struct{})
@@ -562,15 +560,16 @@ func TestResetWithActiveRequests(t *testing.T) {
 	defer close(trafficStopped)
 
 	go func() {
-		r, _ := http.NewRequest("GET", "knative.dev", nil)
+		req, _ := http.NewRequest("GET", "knative.dev", nil)
+		rec := httptest.NewRecorder()
+
 		close(trafficStarted)
 		for {
 			select {
 			case <-trafficStopped:
 				return
 			default:
-				w := httptest.NewRecorder()
-				d.ServeHTTP(w, r)
+				d.ServeHTTP(rec, req)
 			}
 		}
 	}()