Merge pull request #55839 from mindprince/extended-resource-toleration

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add ExtendedResourceToleration admission controller.

/kind feature
/sig scheduling
/area hw-accelerators

There's elaborate discussion on this in #55080. In short, we would like to enable cluster operators and/or cloud providers to create dedicated nodes with extended resources (like GPUs, FPGAs etc.) that are reserved for pods requesting such resources. [Taints is the kubernetes concept to create dedicated nodes.](https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/#example-use-cases) If the cluster operator or cloud provider wants to create dedicated node pools, they are expected to taint the nodes containing extended resources with the key equal to the name of the resource and effect equal to NoSchedule. If they do that, only pods that have a toleration for such a taint can be scheduled there. To make it easy for the user, this admission controller when enabled, automatically adds a toleration with key `example.com/device`, operator `Exists` and effect `NoSchedule` if an extended resource of name `example.com/device` is requested.

**Release note**:
```release-note
Add ExtendedResourceToleration admission controller. This facilitates creation of dedicated nodes with extended resources. If operators want to create dedicated nodes with extended resources (like GPUs, FPGAs etc.), they are expected to taint the node with extended resource name as the key. This admission controller, if enabled, automatically adds tolerations for such taints to pods requesting extended resources, so users don't have to manually add these tolerations. 
```

cmd/kube-apiserver/app/options/BUILD

@@ -30,6 +30,7 @@ go_library(
         "//plugin/pkg/admission/deny:go_default_library",
         "//plugin/pkg/admission/eventratelimit:go_default_library",
         "//plugin/pkg/admission/exec:go_default_library",
+        "//plugin/pkg/admission/extendedresourcetoleration:go_default_library",
         "//plugin/pkg/admission/gc:go_default_library",
         "//plugin/pkg/admission/imagepolicy:go_default_library",
         "//plugin/pkg/admission/initialresources:go_default_library",

cmd/kube-apiserver/app/options/plugins.go

@@ -32,6 +32,7 @@ import (
 	"k8s.io/kubernetes/plugin/pkg/admission/deny"
 	"k8s.io/kubernetes/plugin/pkg/admission/eventratelimit"
 	"k8s.io/kubernetes/plugin/pkg/admission/exec"
+	"k8s.io/kubernetes/plugin/pkg/admission/extendedresourcetoleration"
 	"k8s.io/kubernetes/plugin/pkg/admission/gc"
 	"k8s.io/kubernetes/plugin/pkg/admission/imagepolicy"
 	"k8s.io/kubernetes/plugin/pkg/admission/initialresources"
@@ -61,6 +62,7 @@ func RegisterAllAdmissionPlugins(plugins *admission.Plugins) {
 	deny.Register(plugins)
 	eventratelimit.Register(plugins)
 	exec.Register(plugins)
+	extendedresourcetoleration.Register(plugins)
 	gc.Register(plugins)
 	imagepolicy.Register(plugins)
 	initialresources.Register(plugins)

plugin/BUILD

@@ -19,6 +19,7 @@ filegroup(
         "//plugin/pkg/admission/deny:all-srcs",
         "//plugin/pkg/admission/eventratelimit:all-srcs",
         "//plugin/pkg/admission/exec:all-srcs",
+        "//plugin/pkg/admission/extendedresourcetoleration:all-srcs",
         "//plugin/pkg/admission/gc:all-srcs",
         "//plugin/pkg/admission/imagepolicy:all-srcs",
         "//plugin/pkg/admission/initialresources:all-srcs",

plugin/pkg/admission/extendedresourcetoleration/BUILD

@@ -0,0 +1,42 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["admission.go"],
+    importpath = "k8s.io/kubernetes/plugin/pkg/admission/extendedresourcetoleration",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/apis/core:go_default_library",
+        "//pkg/apis/core/helper:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/admission:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["admission_test.go"],
+    importpath = "k8s.io/kubernetes/plugin/pkg/admission/extendedresourcetoleration",
+    library = ":go_default_library",
+    deps = [
+        "//pkg/apis/core:go_default_library",
+        "//pkg/apis/core/helper:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/api/resource:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/admission:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

plugin/pkg/admission/extendedresourcetoleration/admission.go

@@ -0,0 +1,94 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 extendedresourcetoleration
+
+import (
+	"fmt"
+	"io"
+
+	"k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/kubernetes/pkg/apis/core"
+	"k8s.io/kubernetes/pkg/apis/core/helper"
+)
+
+// Register is called by the apiserver to register the plugin factory.
+func Register(plugins *admission.Plugins) {
+	plugins.Register("ExtendedResourceToleration", func(config io.Reader) (admission.Interface, error) {
+		return newExtendedResourceToleration(), nil
+	})
+}
+
+// newExtendedResourceToleration creates a new instance of the ExtendedResourceToleration admission controller.
+func newExtendedResourceToleration() *plugin {
+	return &plugin{
+		Handler: admission.NewHandler(admission.Create, admission.Update),
+	}
+}
+
+// Make sure we are implementing the interface.
+var _ admission.MutationInterface = &plugin{}
+
+type plugin struct {
+	*admission.Handler
+}
+
+// Admit updates the toleration of a pod based on the resources requested by it.
+// If an extended resource of name "example.com/device" is requested, it adds
+// a toleration with key "example.com/device", operator "Exists" and effect "NoSchedule".
+// The rationale for this is described in:
+// https://github.com/kubernetes/kubernetes/issues/55080
+func (p *plugin) Admit(attributes admission.Attributes) error {
+	// Ignore all calls to subresources or resources other than pods.
+	if len(attributes.GetSubresource()) != 0 || attributes.GetResource().GroupResource() != core.Resource("pods") {
+		return nil
+	}
+
+	pod, ok := attributes.GetObject().(*core.Pod)
+	if !ok {
+		return errors.NewBadRequest(fmt.Sprintf("expected *core.Pod but got %T", attributes.GetObject()))
+	}
+
+	resources := sets.String{}
+	for _, container := range pod.Spec.Containers {
+		for resourceName := range container.Resources.Requests {
+			if helper.IsExtendedResourceName(resourceName) {
+				resources.Insert(string(resourceName))
+			}
+		}
+	}
+	for _, container := range pod.Spec.InitContainers {
+		for resourceName := range container.Resources.Requests {
+			if helper.IsExtendedResourceName(resourceName) {
+				resources.Insert(string(resourceName))
+			}
+		}
+	}
+
+	// Doing .List() so that we get a stable sorted list.
+	// This allows us to test adding tolerations for multiple extended resources.
+	for _, resource := range resources.List() {
+		helper.AddOrUpdateTolerationInPod(pod, &core.Toleration{
+			Key:      resource,
+			Operator: core.TolerationOpExists,
+			Effect:   core.TaintEffectNoSchedule,
+		})
+	}
+
+	return nil
+}

plugin/pkg/admission/extendedresourcetoleration/admission_test.go

@@ -0,0 +1,382 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 extendedresourcetoleration
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/api/resource"
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/kubernetes/pkg/apis/core"
+	"k8s.io/kubernetes/pkg/apis/core/helper"
+)
+
+func TestAdmit(t *testing.T) {
+
+	plugin := newExtendedResourceToleration()
+
+	containerRequestingCPU := core.Container{
+		Resources: core.ResourceRequirements{
+			Requests: core.ResourceList{
+				core.ResourceCPU: *resource.NewQuantity(2, resource.DecimalSI),
+			},
+		},
+	}
+
+	containerRequestingMemory := core.Container{
+		Resources: core.ResourceRequirements{
+			Requests: core.ResourceList{
+				core.ResourceMemory: *resource.NewQuantity(2048, resource.DecimalSI),
+			},
+		},
+	}
+
+	extendedResource1 := "example.com/device-ek"
+	extendedResource2 := "example.com/device-do"
+
+	containerRequestingExtendedResource1 := core.Container{
+		Resources: core.ResourceRequirements{
+			Requests: core.ResourceList{
+				core.ResourceName(extendedResource1): *resource.NewQuantity(1, resource.DecimalSI),
+			},
+		},
+	}
+	containerRequestingExtendedResource2 := core.Container{
+		Resources: core.ResourceRequirements{
+			Requests: core.ResourceList{
+				core.ResourceName(extendedResource2): *resource.NewQuantity(2, resource.DecimalSI),
+			},
+		},
+	}
+
+	tests := []struct {
+		description  string
+		requestedPod core.Pod
+		expectedPod  core.Pod
+	}{
+		{
+			description: "empty pod without any extended resources, expect no change in tolerations",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{},
+			},
+		},
+		{
+			description: "pod with container without any extended resources, expect no change in tolerations",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+					},
+				},
+			},
+		},
+		{
+			description: "pod with init container without any extended resources, expect no change in tolerations",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					InitContainers: []core.Container{
+						containerRequestingMemory,
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					InitContainers: []core.Container{
+						containerRequestingMemory,
+					},
+				},
+			},
+		},
+		{
+			description: "pod with container with extended resource, expect toleration to be added",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingExtendedResource1,
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+		{
+			description: "pod with init container with extended resource, expect toleration to be added",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					InitContainers: []core.Container{
+						containerRequestingExtendedResource2,
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					InitContainers: []core.Container{
+						containerRequestingExtendedResource2,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      extendedResource2,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+		{
+			description: "pod with existing tolerations and container with extended resource, expect existing tolerations to be preserved and new toleration to be added",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      "foo",
+							Operator: core.TolerationOpEqual,
+							Value:    "bar",
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      "foo",
+							Operator: core.TolerationOpEqual,
+							Value:    "bar",
+							Effect:   core.TaintEffectNoSchedule,
+						},
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+		{
+			description: "pod with multiple extended resources, expect multiple tolerations to be added",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					InitContainers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingExtendedResource2,
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					InitContainers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingExtendedResource2,
+					},
+					Tolerations: []core.Toleration{
+						// Note the order, it's sorted by the Key
+						{
+							Key:      extendedResource2,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+		{
+			description: "pod with container requesting extended resource and existing correct toleration, expect no change in tolerations",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+		{
+			description: "pod with container requesting extended resource and existing toleration with the same key but different effect and value, expect existing tolerations to be preserved and new toleration to be added",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpEqual,
+							Value:    "foo",
+							Effect:   core.TaintEffectNoExecute,
+						},
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpEqual,
+							Value:    "foo",
+							Effect:   core.TaintEffectNoExecute,
+						},
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+		{
+			description: "pod with wildcard toleration and container requesting extended resource, expect existing tolerations to be preserved and new toleration to be added",
+			requestedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Operator: core.TolerationOpExists,
+						},
+					},
+				},
+			},
+			expectedPod: core.Pod{
+				Spec: core.PodSpec{
+					Containers: []core.Container{
+						containerRequestingCPU,
+						containerRequestingMemory,
+						containerRequestingExtendedResource1,
+					},
+					Tolerations: []core.Toleration{
+						{
+							Operator: core.TolerationOpExists,
+						},
+						{
+							Key:      extendedResource1,
+							Operator: core.TolerationOpExists,
+							Effect:   core.TaintEffectNoSchedule,
+						},
+					},
+				},
+			},
+		},
+	}
+	for i, test := range tests {
+		err := plugin.Admit(admission.NewAttributesRecord(&test.requestedPod, nil, core.Kind("Pod").WithVersion("version"), "foo", "name", core.Resource("pods").WithVersion("version"), "", "ignored", nil))
+		if err != nil {
+			t.Errorf("[%d: %s] unexpected error %v for pod %+v", i, test.description, err, test.requestedPod)
+		}
+
+		if !helper.Semantic.DeepEqual(test.expectedPod.Spec.Tolerations, test.requestedPod.Spec.Tolerations) {
+			t.Errorf("[%d: %s] expected %#v got %#v", i, test.description, test.expectedPod.Spec.Tolerations, test.requestedPod.Spec.Tolerations)
+		}
+	}
+}
+
+func TestHandles(t *testing.T) {
+	plugin := newExtendedResourceToleration()
+	tests := map[admission.Operation]bool{
+		admission.Create:  true,
+		admission.Update:  true,
+		admission.Delete:  false,
+		admission.Connect: false,
+	}
+	for op, expected := range tests {
+		result := plugin.Handles(op)
+		if result != expected {
+			t.Errorf("Unexpected result for operation %s: %v\n", op, result)
+		}
+	}
+}