Add support for binaries to run as Windows services

This patch adds support for kubernetes to integrate
with Windows SCM.

As a first step both `kubelet` and `kube-proxy` can be registered as a service.

To create the service:
PS > sc.exe create <component_name> binPath= "<path_to_binary> --service <other_args>"
CMD > sc create <component_name> binPath= "<path_to_binary> --service <other_args>"

Please note that if the arguments contain spaces, it must be escaped.
Example:
PS > sc.exe create kubelet binPath= "C:\kubelet.exe --service --hostname-override 'minion' <other_args>"
CMD > sc create kubelet binPath= "C:\kubelet.exe --service --hostname-override 'minion' <other_args>"

Example to start the service:
PS > Start-Service kubelet; Start-Service kube-proxy
CMD > net start kubelet && net start kube-proxy

Example to stop the service:
PS > Stop-Service kubelet (-Force); Stop-Service kube-proxy (-Force)
CMD > net stop kubelet && net stop kube-proxy

Example to query the service:
PS > Get-Service kubelet; Get-Service kube-proxy;
CMD > sc.exe queryex kubelet && sc qc kubelet && sc.exe queryex kube-proxy && sc.exe qc kube-proxy

Signed-off-by: Alin Balutoiu <abalutoiu@cloudbasesolutions.com>
Signed-off-by: Alin Gabriel Serdean <aserdean@ovn.org>
Co-authored-by: Alin Gabriel Serdean <aserdean@ovn.org>

cmd/kubelet/app/BUILD

@@ -20,36 +20,47 @@ go_library(
         "server.go",
     ] + select({
         "@io_bazel_rules_go//go/platform:android": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:darwin": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:dragonfly": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:freebsd": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:linux": [
+            "init_others.go",
             "server_linux.go",
         ],
         "@io_bazel_rules_go//go/platform:nacl": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:netbsd": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:openbsd": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:plan9": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:solaris": [
+            "init_others.go",
             "server_unsupported.go",
         ],
         "@io_bazel_rules_go//go/platform:windows": [
+            "init_windows.go",
             "server_unsupported.go",
         ],
         "//conditions:default": [],
@@ -162,6 +173,9 @@ go_library(
         "@io_bazel_rules_go//go/platform:linux": [
             "//vendor/golang.org/x/exp/inotify:go_default_library",
         ],
+        "@io_bazel_rules_go//go/platform:windows": [
+            "//pkg/windows/service:go_default_library",
+        ],
         "//conditions:default": [],
     }),
 )

cmd/kubelet/app/init_others.go

@@ -0,0 +1,23 @@
+// +build !windows
+
+/*
+Copyright 2018 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 app
+
+func initForOS(service bool) error {
+	return nil
+}

cmd/kubelet/app/init_windows.go

@@ -0,0 +1,34 @@
+// +build windows
+
+/*
+Copyright 2018 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 app
+
+import (
+	"k8s.io/kubernetes/pkg/windows/service"
+)
+
+const (
+	serviceName = "kubelet"
+)
+
+func initForOS(windowsService bool) error {
+	if windowsService {
+		return service.InitService(serviceName)
+	}
+	return nil
+}

cmd/kubelet/app/options/BUILD

@@ -15,36 +15,47 @@ go_library(
     ] + select({
         "@io_bazel_rules_go//go/platform:android": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:darwin": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:dragonfly": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:freebsd": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:linux": [
             "globalflags_linux.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:nacl": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:netbsd": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:openbsd": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:plan9": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:solaris": [
             "globalflags_other.go",
+            "osflags_others.go",
         ],
         "@io_bazel_rules_go//go/platform:windows": [
             "globalflags_other.go",
+            "osflags_windows.go",
         ],
         "//conditions:default": [],
     }),

cmd/kubelet/app/options/options.go

@@ -125,6 +125,10 @@ type KubeletFlags struct {
 	// cAdvisorPort is the port of the localhost cAdvisor endpoint (set to 0 to disable)
 	CAdvisorPort int32
 
+	// WindowsService should be set to true if kubelet is running as a service on Windows.
+	// Its corresponding flag only gets registered in Windows builds.
+	WindowsService bool
+
 	// EXPERIMENTAL FLAGS
 	// Whitelist of unsafe sysctls or sysctl patterns (ending in *).
 	// +optional
@@ -329,6 +333,7 @@ func (s *KubeletServer) AddFlags(fs *pflag.FlagSet) {
 // AddFlags adds flags for a specific KubeletFlags to the specified FlagSet
 func (f *KubeletFlags) AddFlags(fs *pflag.FlagSet) {
 	f.ContainerRuntimeOptions.AddFlags(fs)
+	f.addOSFlags(fs)
 
 	fs.StringVar(&f.KubeletConfigFile, "config", f.KubeletConfigFile, "The Kubelet will load its initial configuration from this file. The path may be absolute or relative; relative paths start at the Kubelet's current working directory. Omit this flag to use the built-in default configuration values. Command-line flags override configuration from this file.")
 	fs.StringVar(&f.KubeConfig, "kubeconfig", f.KubeConfig, "Path to a kubeconfig file, specifying how to connect to the API server. Providing --kubeconfig enables API server mode, omitting --kubeconfig enables standalone mode.")

cmd/kubelet/app/options/osflags_others.go

@@ -0,0 +1,26 @@
+// +build !windows
+
+/*
+Copyright 2018 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 options
+
+import (
+	"github.com/spf13/pflag"
+)
+
+func (f *KubeletFlags) addOSFlags(fs *pflag.FlagSet) {
+}

cmd/kubelet/app/options/osflags_windows.go

@@ -0,0 +1,27 @@
+// +build windows
+
+/*
+Copyright 2018 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 options
+
+import (
+	"github.com/spf13/pflag"
+)
+
+func (f *KubeletFlags) addOSFlags(fs *pflag.FlagSet) {
+	fs.BoolVar(&f.WindowsService, "windows-service", f.WindowsService, "Enable Windows Service Control Manager API integration")
+}

cmd/kubelet/app/server.go

@@ -373,6 +373,9 @@ func UnsecuredDependencies(s *options.KubeletServer) (*kubelet.Dependencies, err
 func Run(s *options.KubeletServer, kubeDeps *kubelet.Dependencies) error {
 	// To help debugging, immediately log version
 	glog.Infof("Version: %+v", version.Get())
+	if err := initForOS(s.KubeletFlags.WindowsService); err != nil {
+		return fmt.Errorf("failed OS init: %v", err)
+	}
 	if err := run(s, kubeDeps); err != nil {
 		return fmt.Errorf("failed to run Kubelet: %v", err)
 	}