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

cmd/kubelet/app/server.go

@@ -108,6 +108,7 @@ type KubeletServer struct {
 	ContainerRuntime               string
 	DockerDaemonContainer          string
 	ConfigureCBR0                  bool
+	MaxPods                        int
 
 	// Flags intended for testing
 
@@ -226,6 +227,7 @@ func (s *KubeletServer) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&s.ContainerRuntime, "container_runtime", s.ContainerRuntime, "The container runtime to use. Possible values: 'docker', 'rkt'. Default: 'docker'.")
 	fs.StringVar(&s.DockerDaemonContainer, "docker-daemon-container", s.DockerDaemonContainer, "Optional resource-only container in which to place the Docker Daemon. Empty for no container (Default: /docker-daemon).")
 	fs.BoolVar(&s.ConfigureCBR0, "configure-cbr0", s.ConfigureCBR0, "If true, kubelet will configure cbr0 based on Node.Spec.PodCIDR.")
+	fs.IntVar(&s.MaxPods, "max_pods", 100, "Number of Pods that can run on this Kubelet.")
 
 	// Flags intended for testing, not recommended used in production environments.
 	fs.BoolVar(&s.ReallyCrashForTesting, "really-crash-for-testing", s.ReallyCrashForTesting, "If true, when panics occur crash. Intended for testing.")
@@ -342,6 +344,7 @@ func (s *KubeletServer) Run(_ []string) error {
 		Mounter:                   mounter,
 		DockerDaemonContainer:     s.DockerDaemonContainer,
 		ConfigureCBR0:             s.ConfigureCBR0,
+		MaxPods:                   s.MaxPods,
 	}
 
 	RunKubelet(&kcfg, nil)
@@ -500,6 +503,7 @@ func SimpleKubelet(client *client.Client,
 		ContainerRuntime:          "docker",
 		Mounter:                   mount.New(),
 		DockerDaemonContainer:     "/docker-daemon",
+		MaxPods:                   32,
 	}
 	return &kcfg
 }
@@ -633,6 +637,7 @@ type KubeletConfig struct {
 	Mounter                        mount.Interface
 	DockerDaemonContainer          string
 	ConfigureCBR0                  bool
+	MaxPods                        int
 }
 
 func createAndInitKubelet(kc *KubeletConfig) (k KubeletBootstrap, pc *config.PodConfig, err error) {
@@ -683,7 +688,8 @@ func createAndInitKubelet(kc *KubeletConfig) (k KubeletBootstrap, pc *config.Pod
 		kc.ContainerRuntime,
 		kc.Mounter,
 		kc.DockerDaemonContainer,
-		kc.ConfigureCBR0)
+		kc.ConfigureCBR0,
+		kc.MaxPods)
 
 	if err != nil {
 		return nil, nil, err

pkg/api/resource_helpers.go

@@ -41,6 +41,13 @@ func (self *ResourceList) Memory() *resource.Quantity {
 	return &resource.Quantity{}
 }
 
+func (self *ResourceList) MaxPods() *resource.Quantity {
+	if val, ok := (*self)[ResourceMaxPods]; ok {
+		return &val
+	}
+	return &resource.Quantity{}
+}
+
 func GetContainerStatus(statuses []ContainerStatus, name string) (ContainerStatus, bool) {
 	for i := range statuses {
 		if statuses[i].Name == name {

pkg/api/types.go

@@ -1238,6 +1238,8 @@ const (
 	ResourceMemory ResourceName = "memory"
 	// Volume size, in bytes (e,g. 5Gi = 5GiB = 5 * 1024 * 1024 * 1024)
 	ResourceStorage ResourceName = "storage"
+	// Number of Pods that may be running on this Node.
+	ResourceMaxPods ResourceName = "maxpods"
 )
 
 // ResourceList is a set of (resource name, quantity) pairs.

pkg/cloudprovider/nodecontroller/nodecontroller.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	apierrors "github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/resource"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/record"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/cloudprovider"
@@ -670,6 +671,9 @@ func (nc *NodeController) getCloudNodesWithSpec() (*api.NodeList, error) {
 		}
 		if resources != nil {
 			node.Status.Capacity = resources.Capacity
+			if node.Status.Capacity != nil {
+				node.Status.Capacity[api.ResourceMaxPods] = *resource.NewQuantity(0, resource.DecimalSI)
+			}
 		}
 		instanceID, err := instances.ExternalID(node.Name)
 		if err != nil {

pkg/kubelet/kubelet.go

@@ -31,6 +31,7 @@ import (
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/resource"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/validation"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/cache"
@@ -57,6 +58,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
 	"github.com/GoogleCloudPlatform/kubernetes/plugin/pkg/scheduler/algorithm/predicates"
 	"github.com/golang/glog"
+
 	cadvisorApi "github.com/google/cadvisor/info/v1"
 )
 
@@ -139,7 +141,8 @@ func NewMainKubelet(
 	containerRuntime string,
 	mounter mount.Interface,
 	dockerDaemonContainer string,
-	configureCBR0 bool) (*Kubelet, error) {
+	configureCBR0 bool,
+	maxPods int) (*Kubelet, error) {
 	if rootDirectory == "" {
 		return nil, fmt.Errorf("invalid root directory %q", rootDirectory)
 	}
@@ -246,6 +249,7 @@ func NewMainKubelet(
 		cgroupRoot:                     cgroupRoot,
 		mounter:                        mounter,
 		configureCBR0:                  configureCBR0,
+		maxPods:                        maxPods,
 	}
 
 	if plug, err := network.InitNetworkPlugin(networkPlugins, networkPluginName, &networkHost{klet}); err != nil {
@@ -462,6 +466,9 @@ type Kubelet struct {
 	// Whether or not kubelet should take responsibility for keeping cbr0 in
 	// the correct state.
 	configureCBR0 bool
+
+	// Number of Pods which can be run by this Kubelet
+	maxPods int
 }
 
 // getRootDir returns the full path to the directory under which kubelet can
@@ -1673,6 +1680,8 @@ func (kl *Kubelet) tryUpdateNodeStatus() error {
 		node.Status.NodeInfo.MachineID = info.MachineID
 		node.Status.NodeInfo.SystemUUID = info.SystemUUID
 		node.Status.Capacity = CapacityFromMachineInfo(info)
+		node.Status.Capacity[api.ResourceMaxPods] = *resource.NewQuantity(
+			int64(kl.maxPods), resource.DecimalSI)
 		if node.Status.NodeInfo.BootID != "" &&
 			node.Status.NodeInfo.BootID != info.BootID {
 			// TODO: This requires a transaction, either both node status is updated

pkg/kubelet/kubelet_test.go

@@ -3310,8 +3310,9 @@ func TestUpdateNewNodeStatus(t *testing.T) {
 				KubeProxyVersion:        version.Get().String(),
 			},
 			Capacity: api.ResourceList{
-				api.ResourceCPU:    *resource.NewMilliQuantity(2000, resource.DecimalSI),
-				api.ResourceMemory: *resource.NewQuantity(1024, resource.BinarySI),
+				api.ResourceCPU:     *resource.NewMilliQuantity(2000, resource.DecimalSI),
+				api.ResourceMemory:  *resource.NewQuantity(1024, resource.BinarySI),
+				api.ResourceMaxPods: *resource.NewQuantity(0, resource.DecimalSI),
 			},
 		},
 	}
@@ -3359,8 +3360,9 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 					},
 				},
 				Capacity: api.ResourceList{
-					api.ResourceCPU:    *resource.NewMilliQuantity(3000, resource.DecimalSI),
-					api.ResourceMemory: *resource.NewQuantity(2048, resource.BinarySI),
+					api.ResourceCPU:     *resource.NewMilliQuantity(3000, resource.DecimalSI),
+					api.ResourceMemory:  *resource.NewQuantity(2048, resource.BinarySI),
+					api.ResourceMaxPods: *resource.NewQuantity(0, resource.DecimalSI),
 				},
 			},
 		},
@@ -3404,8 +3406,9 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 				KubeProxyVersion:        version.Get().String(),
 			},
 			Capacity: api.ResourceList{
-				api.ResourceCPU:    *resource.NewMilliQuantity(2000, resource.DecimalSI),
-				api.ResourceMemory: *resource.NewQuantity(1024, resource.BinarySI),
+				api.ResourceCPU:     *resource.NewMilliQuantity(2000, resource.DecimalSI),
+				api.ResourceMemory:  *resource.NewQuantity(1024, resource.BinarySI),
+				api.ResourceMaxPods: *resource.NewQuantity(0, resource.DecimalSI),
 			},
 		},
 	}
@@ -3488,8 +3491,9 @@ func TestUpdateNodeStatusWithoutContainerRuntime(t *testing.T) {
 				KubeProxyVersion:        version.Get().String(),
 			},
 			Capacity: api.ResourceList{
-				api.ResourceCPU:    *resource.NewMilliQuantity(2000, resource.DecimalSI),
-				api.ResourceMemory: *resource.NewQuantity(1024, resource.BinarySI),
+				api.ResourceCPU:     *resource.NewMilliQuantity(2000, resource.DecimalSI),
+				api.ResourceMemory:  *resource.NewQuantity(1024, resource.BinarySI),
+				api.ResourceMaxPods: *resource.NewQuantity(0, resource.DecimalSI),
 			},
 		},
 	}

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")

test/integration/scheduler_test.go

@@ -29,6 +29,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/resource"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/testapi"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/apiserver"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
@@ -144,6 +145,9 @@ func DoTestUnschedulableNodes(t *testing.T, restClient *client.Client, nodeStore
 		ObjectMeta: api.ObjectMeta{Name: "node-scheduling-test-node"},
 		Spec:       api.NodeSpec{Unschedulable: false},
 		Status: api.NodeStatus{
+			Capacity: api.ResourceList{
+				"maxpods": *resource.NewQuantity(32, resource.DecimalSI),
+			},
 			Conditions: []api.NodeCondition{goodCondition},
 		},
 	}
@@ -194,6 +198,9 @@ func DoTestUnschedulableNodes(t *testing.T, restClient *client.Client, nodeStore
 		{
 			makeUnSchedulable: func(t *testing.T, n *api.Node, s cache.Store, c *client.Client) {
 				n.Status = api.NodeStatus{
+					Capacity: api.ResourceList{
+						"maxpods": *resource.NewQuantity(32, resource.DecimalSI),
+					},
 					Conditions: []api.NodeCondition{badCondition},
 				}
 				if _, err = c.Nodes().UpdateStatus(n); err != nil {
@@ -208,6 +215,9 @@ func DoTestUnschedulableNodes(t *testing.T, restClient *client.Client, nodeStore
 			},
 			makeSchedulable: func(t *testing.T, n *api.Node, s cache.Store, c *client.Client) {
 				n.Status = api.NodeStatus{
+					Capacity: api.ResourceList{
+						"maxpods": *resource.NewQuantity(32, resource.DecimalSI),
+					},
 					Conditions: []api.NodeCondition{goodCondition},
 				}
 				if _, err = c.Nodes().UpdateStatus(n); err != nil {