From c5e82a01b15136141801ba93de810fdf3165086b Mon Sep 17 00:00:00 2001
From: Seth Jennings <sjenning@redhat.com>
Date: Tue, 19 Jul 2016 10:54:38 -0500
Subject: [PATCH] hpa: ignore scale targets whose replica count is 0

---
 pkg/controller/podautoscaler/horizontal.go      | 7 +++++--
 pkg/controller/podautoscaler/horizontal_test.go | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/pkg/controller/podautoscaler/horizontal.go b/pkg/controller/podautoscaler/horizontal.go
index 9c6cc436b13..a6c2e0a2607 100644
--- a/pkg/controller/podautoscaler/horizontal.go
+++ b/pkg/controller/podautoscaler/horizontal.go
@@ -271,7 +271,10 @@ func (a *HorizontalController) reconcileAutoscaler(hpa *autoscaling.HorizontalPo
 	rescaleReason := ""
 	timestamp := time.Now()
 
-	if currentReplicas > hpa.Spec.MaxReplicas {
+	if scale.Spec.Replicas == 0 {
+		// Autoscaling is disabled for this resource
+		desiredReplicas = 0
+	} else if currentReplicas > hpa.Spec.MaxReplicas {
 		rescaleReason = "Current number of replicas above Spec.MaxReplicas"
 		desiredReplicas = hpa.Spec.MaxReplicas
 	} else if hpa.Spec.MinReplicas != nil && currentReplicas < *hpa.Spec.MinReplicas {
@@ -323,7 +326,7 @@ func (a *HorizontalController) reconcileAutoscaler(hpa *autoscaling.HorizontalPo
 			desiredReplicas = *hpa.Spec.MinReplicas
 		}
 
-		// TODO: remove when pod idling is done.
+		//  never scale down to 0, reserved for disabling autoscaling
 		if desiredReplicas == 0 {
 			desiredReplicas = 1
 		}
diff --git a/pkg/controller/podautoscaler/horizontal_test.go b/pkg/controller/podautoscaler/horizontal_test.go
index 611794402af..20f4e5ac416 100644
--- a/pkg/controller/podautoscaler/horizontal_test.go
+++ b/pkg/controller/podautoscaler/horizontal_test.go
@@ -665,7 +665,7 @@ func TestZeroReplicas(t *testing.T) {
 		minReplicas:         3,
 		maxReplicas:         5,
 		initialReplicas:     0,
-		desiredReplicas:     3,
+		desiredReplicas:     0,
 		CPUTarget:           90,
 		reportedLevels:      []uint64{},
 		reportedCPURequests: []resource.Quantity{},