Add a resource specifying number of Pods that are allowed to run on Kubelet.

plugin/pkg/scheduler/algorithm/predicates/predicates.go

@@ -137,19 +137,18 @@ func CheckPodsExceedingCapacity(pods []*api.Pod, capacity api.ResourceList) (fit
 // PodFitsResources calculates fit based on requested, rather than used resources
 func (r *ResourceFit) PodFitsResources(pod *api.Pod, existingPods []*api.Pod, node string) (bool, error) {
 	podRequest := getResourceRequest(pod)
-	if podRequest.milliCPU == 0 && podRequest.memory == 0 {
-		// no resources requested always fits.
-		return true, nil
-	}
 	info, err := r.info.GetNodeInfo(node)
 	if err != nil {
 		return false, err
 	}
+	if podRequest.milliCPU == 0 && podRequest.memory == 0 {
+		return int64(len(existingPods)) < info.Status.Capacity.MaxPods().Value(), nil
+	}
 	pods := []*api.Pod{}
 	copy(pods, existingPods)
 	pods = append(existingPods, pod)
 	_, exceeding := CheckPodsExceedingCapacity(pods, info.Status.Capacity)
-	if len(exceeding) > 0 {
+	if len(exceeding) > 0 || int64(len(pods)) > info.Status.Capacity.MaxPods().Value() {
 		return false, nil
 	}
 	return true, nil

plugin/pkg/scheduler/algorithm/predicates/predicates_test.go

@@ -44,11 +44,12 @@ func (nodes FakeNodeListInfo) GetNodeInfo(nodeName string) (*api.Node, error) {
 	return nil, fmt.Errorf("Unable to find node: %s", nodeName)
 }
 
-func makeResources(milliCPU int64, memory int64) api.NodeResources {
+func makeResources(milliCPU int64, memory int64, maxPods int64) api.NodeResources {
 	return api.NodeResources{
 		Capacity: api.ResourceList{
-			"cpu":    *resource.NewMilliQuantity(milliCPU, resource.DecimalSI),
-			"memory": *resource.NewQuantity(memory, resource.BinarySI),
+			"cpu":     *resource.NewMilliQuantity(milliCPU, resource.DecimalSI),
+			"memory":  *resource.NewQuantity(memory, resource.BinarySI),
+			"maxpods": *resource.NewQuantity(maxPods, resource.DecimalSI),
 		},
 	}
 }
@@ -73,7 +74,8 @@ func newResourcePod(usage ...resourceRequest) *api.Pod {
 }
 
 func TestPodFitsResources(t *testing.T) {
-	tests := []struct {
+
+	enoughPodsTests := []struct {
 		pod          *api.Pod
 		existingPods []*api.Pod
 		fits         bool
@@ -120,8 +122,53 @@ func TestPodFitsResources(t *testing.T) {
 			test: "equal edge case",
 		},
 	}
-	for _, test := range tests {
-		node := api.Node{Status: api.NodeStatus{Capacity: makeResources(10, 20).Capacity}}
+
+	for _, test := range enoughPodsTests {
+		node := api.Node{Status: api.NodeStatus{Capacity: makeResources(10, 20, 32).Capacity}}
+
+		fit := ResourceFit{FakeNodeInfo(node)}
+		fits, err := fit.PodFitsResources(test.pod, test.existingPods, "machine")
+		if err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+		if fits != test.fits {
+			t.Errorf("%s: expected: %v got %v", test.test, test.fits, fits)
+		}
+	}
+
+	notEnoughPodsTests := []struct {
+		pod          *api.Pod
+		existingPods []*api.Pod
+		fits         bool
+		test         string
+	}{
+		{
+			pod: &api.Pod{},
+			existingPods: []*api.Pod{
+				newResourcePod(resourceRequest{milliCPU: 10, memory: 20}),
+			},
+			fits: false,
+			test: "even without specified resources predicate fails when there's no available ips",
+		},
+		{
+			pod: newResourcePod(resourceRequest{milliCPU: 1, memory: 1}),
+			existingPods: []*api.Pod{
+				newResourcePod(resourceRequest{milliCPU: 5, memory: 5}),
+			},
+			fits: false,
+			test: "even if both resources fit predicate fails when there's no available ips",
+		},
+		{
+			pod: newResourcePod(resourceRequest{milliCPU: 5, memory: 1}),
+			existingPods: []*api.Pod{
+				newResourcePod(resourceRequest{milliCPU: 5, memory: 19}),
+			},
+			fits: false,
+			test: "even for equal edge case predicate fails when there's no available ips",
+		},
+	}
+	for _, test := range notEnoughPodsTests {
+		node := api.Node{Status: api.NodeStatus{Capacity: makeResources(10, 20, 1).Capacity}}
 
 		fit := ResourceFit{FakeNodeInfo(node)}
 		fits, err := fit.PodFitsResources(test.pod, test.existingPods, "machine")