Admission control plugin for resource defaults

cluster/vagrant/provision-master.sh

@@ -75,7 +75,7 @@ grains:
   cloud_provider: vagrant
   roles:
     - kubernetes-master
-  admission_control: AlwaysAdmit
+  admission_control: ResourceDefaults,AlwaysAdmit
 EOF
 
 mkdir -p /srv/salt-overlay/pillar

cmd/kube-apiserver/plugins.go

@@ -28,4 +28,5 @@ import (
 
 	_ "github.com/GoogleCloudPlatform/kubernetes/plugin/pkg/admission/admit"
 	_ "github.com/GoogleCloudPlatform/kubernetes/plugin/pkg/admission/deny"
+	_ "github.com/GoogleCloudPlatform/kubernetes/plugin/pkg/admission/resourcedefaults"
 )

plugin/pkg/admission/resourcedefaults/admission.go

@@ -0,0 +1,70 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package resourcedefaults
+
+import (
+	"io"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/admission"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/resource"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+)
+
+func init() {
+	admission.RegisterPlugin("ResourceDefaults", func(client client.Interface, config io.Reader) (admission.Interface, error) {
+		return NewResourceDefaults(), nil
+	})
+}
+
+const (
+	defaultMemory string = "512Mi"
+	defaultCPU    string = "1"
+)
+
+// resourceDefaults is an implementation of admission.Interface which applies default resource limits (cpu/memory)
+// It is useful for clusters that do not want to support unlimited usage constraints, but instead supply sensible defaults
+type resourceDefaults struct{}
+
+func (resourceDefaults) Admit(a admission.Attributes) (err error) {
+	// ignore deletes, only process create and update
+	if a.GetOperation() == "DELETE" {
+		return nil
+	}
+
+	// we only care about pods
+	if a.GetKind() != "pods" {
+		return nil
+	}
+
+	// get the pod, so we can validate each of the containers within have default mem / cpu constraints
+	obj := a.GetObject()
+	pod := obj.(*api.Pod)
+	for index := range pod.Spec.Containers {
+		if pod.Spec.Containers[index].Memory.Value() == 0 {
+			pod.Spec.Containers[index].Memory = resource.MustParse(defaultMemory)
+		}
+		if pod.Spec.Containers[index].CPU.Value() == 0 {
+			pod.Spec.Containers[index].CPU = resource.MustParse(defaultCPU)
+		}
+	}
+	return nil
+}
+
+func NewResourceDefaults() admission.Interface {
+	return new(resourceDefaults)
+}

plugin/pkg/admission/resourcedefaults/admission_test.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package resourcedefaults
+
+import (
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/admission"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+)
+
+func TestAdmission(t *testing.T) {
+	namespace := "default"
+
+	handler := NewResourceDefaults()
+	pod := api.Pod{
+		ObjectMeta: api.ObjectMeta{Name: "123", Namespace: "ns"},
+		Spec: api.PodSpec{
+			Volumes:    []api.Volume{{Name: "vol"}},
+			Containers: []api.Container{{Name: "ctr", Image: "image"}},
+		},
+	}
+
+	err := handler.Admit(admission.NewAttributesRecord(&pod, namespace, "pods", "CREATE"))
+	if err != nil {
+		t.Errorf("Unexpected error returned from admission handler")
+	}
+
+	for i := range pod.Spec.Containers {
+		if pod.Spec.Containers[i].Memory.String() != "512Mi" {
+			t.Errorf("Unexpected memory value %s", pod.Spec.Containers[i].Memory.String())
+		}
+		if pod.Spec.Containers[i].CPU.String() != "1" {
+			t.Errorf("Unexpected cpu value %s", pod.Spec.Containers[i].CPU.String())
+		}
+	}
+}