HPA Controller: Check for 0-sum request value

pkg/controller/podautoscaler/metrics/utilization.go

@@ -16,6 +16,10 @@ limitations under the License.
 
 package metrics
 
+import (
+	"fmt"
+)
+
 // GetResourceUtilizationRatio takes in a set of metrics, a set of matching requests,
 // and a target utilization percentage, and calcuates the the ratio of
 // desired to actual utilization (returning that and the actual utilization)
@@ -34,6 +38,12 @@ func GetResourceUtilizationRatio(metrics PodResourceInfo, requests map[string]in
 		requestsTotal += request
 	}
 
+	// if the set of requests is completely disjoint from the set of metrics,
+	// then we could have an issue where the requests total is zero
+	if requestsTotal == 0 {
+		return 0, 0, fmt.Errorf("no metrics returned matched known pods")
+	}
+
 	currentUtilization := int32((metricsTotal * 100) / requestsTotal)
 
 	return float64(currentUtilization) / float64(targetUtilization), currentUtilization, nil

pkg/controller/podautoscaler/replica_calculator_test.go

@@ -47,6 +47,8 @@ type resourceInfo struct {
 	name     v1.ResourceName
 	requests []resource.Quantity
 	levels   []int64
+	// only applies to pod names returned from "heapster"
+	podNames []string
 
 	targetUtilization   int32
 	expectedUtilization int32
@@ -134,9 +136,13 @@ func (tc *replicaCalcTestCase) prepareTestClient(t *testing.T) *fake.Clientset {
 		if tc.resource != nil {
 			metrics := metricsapi.PodMetricsList{}
 			for i, resValue := range tc.resource.levels {
+				podName := fmt.Sprintf("%s-%d", podNamePrefix, i)
+				if len(tc.resource.podNames) > i {
+					podName = tc.resource.podNames[i]
+				}
 				podMetric := metricsapi.PodMetrics{
 					ObjectMeta: v1.ObjectMeta{
-						Name:      fmt.Sprintf("%s-%d", podNamePrefix, i),
+						Name:      podName,
 						Namespace: testNamespace,
 					},
 					Timestamp: unversioned.Time{Time: tc.timestamp},
@@ -250,6 +256,22 @@ func (tc *replicaCalcTestCase) runTest(t *testing.T) {
 	}
 }
 
+func TestReplicaCalcDisjointResourcesMetrics(t *testing.T) {
+	tc := replicaCalcTestCase{
+		currentReplicas: 1,
+		expectedError:   fmt.Errorf("no metrics returned matched known pods"),
+		resource: &resourceInfo{
+			name:     v1.ResourceCPU,
+			requests: []resource.Quantity{resource.MustParse("1.0")},
+			levels:   []int64{100},
+			podNames: []string{"an-older-pod-name"},
+
+			targetUtilization: 100,
+		},
+	}
+	tc.runTest(t)
+}
+
 func TestReplicaCalcScaleUp(t *testing.T) {
 	tc := replicaCalcTestCase{
 		currentReplicas:  3,