Add sysctl whitelist on the node

pkg/kubelet/sysctl/runtime.go

@@ -0,0 +1,96 @@
+/*
+Copyright 2016 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 sysctl
+
+import (
+	"fmt"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/kubelet/dockertools"
+	"k8s.io/kubernetes/pkg/kubelet/lifecycle"
+)
+
+const (
+	UnsupportedReason = "SysctlUnsupported"
+)
+
+type runtimeAdmitHandler struct {
+	result lifecycle.PodAdmitResult
+}
+
+var _ lifecycle.PodAdmitHandler = &runtimeAdmitHandler{}
+
+// NewRuntimeAdmitHandler returns a sysctlRuntimeAdmitHandler which checks whether
+// the given runtime support sysctls.
+func NewRuntimeAdmitHandler(runtime container.Runtime) (*runtimeAdmitHandler, error) {
+	if runtime.Type() == dockertools.DockerType {
+		v, err := runtime.APIVersion()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get runtime version: %v", err)
+		}
+
+		// only Docker >= 1.12 supports sysctls
+		c, err := v.Compare(dockertools.DockerV112APIVersion)
+		if err != nil {
+			return nil, fmt.Errorf("failed to compare Docker version for sysctl support: %v", err)
+		}
+		if c >= 0 {
+			return &runtimeAdmitHandler{
+				result: lifecycle.PodAdmitResult{
+					Admit: true,
+				},
+			}, nil
+		}
+		return &runtimeAdmitHandler{
+			result: lifecycle.PodAdmitResult{
+				Admit:   false,
+				Reason:  UnsupportedReason,
+				Message: "Docker before 1.12 does not support sysctls",
+			},
+		}, nil
+	}
+
+	// for other runtimes like rkt sysctls are not supported
+	return &runtimeAdmitHandler{
+		result: lifecycle.PodAdmitResult{
+			Admit:   false,
+			Reason:  UnsupportedReason,
+			Message: fmt.Sprintf("runtime %v does not support sysctls", runtime.Type()),
+		},
+	}, nil
+}
+
+// Admit checks whether the runtime supports sysctls.
+func (w *runtimeAdmitHandler) Admit(attrs *lifecycle.PodAdmitAttributes) lifecycle.PodAdmitResult {
+	sysctls, unsafeSysctls, err := api.SysctlsFromPodAnnotations(attrs.Pod.Annotations)
+	if err != nil {
+		return lifecycle.PodAdmitResult{
+			Admit:   false,
+			Reason:  AnnotationInvalidReason,
+			Message: fmt.Sprintf("invalid sysctl annotation: %v", err),
+		}
+	}
+
+	if len(sysctls)+len(unsafeSysctls) > 0 {
+		return w.result
+	}
+
+	return lifecycle.PodAdmitResult{
+		Admit: true,
+	}
+}