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			116 lines
		
	
	
		
			3.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// +build windows
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/*
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Copyright 2018 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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    http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package service
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import (
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	"os"
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	"time"
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	"k8s.io/apiserver/pkg/server"
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	"k8s.io/klog"
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	"golang.org/x/sys/windows"
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	"golang.org/x/sys/windows/svc"
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)
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var (
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	service *handler
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)
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type handler struct {
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	tosvc   chan bool
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	fromsvc chan error
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}
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// InitService is the entry point for running the daemon as a Windows
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// service. It returns an indication of whether it is running as a service;
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// and an error.
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func InitService(serviceName string) error {
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	h := &handler{
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		tosvc:   make(chan bool),
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		fromsvc: make(chan error),
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	}
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	service = h
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	var err error
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	go func() {
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		err = svc.Run(serviceName, h)
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		h.fromsvc <- err
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	}()
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	// Wait for the first signal from the service handler.
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	err = <-h.fromsvc
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	if err != nil {
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		return err
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	}
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	klog.Infof("Running %s as a Windows service!", serviceName)
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	return nil
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}
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func (h *handler) Execute(_ []string, r <-chan svc.ChangeRequest, s chan<- svc.Status) (bool, uint32) {
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	s <- svc.Status{State: svc.StartPending, Accepts: 0}
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	// Unblock initService()
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	h.fromsvc <- nil
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	s <- svc.Status{State: svc.Running, Accepts: svc.AcceptStop | svc.AcceptShutdown | svc.Accepted(windows.SERVICE_ACCEPT_PARAMCHANGE)}
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	klog.Infof("Service running")
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Loop:
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	for {
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		select {
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		case <-h.tosvc:
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			break Loop
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		case c := <-r:
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			switch c.Cmd {
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			case svc.Cmd(windows.SERVICE_CONTROL_PARAMCHANGE):
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				s <- c.CurrentStatus
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			case svc.Interrogate:
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				s <- c.CurrentStatus
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			case svc.Stop, svc.Shutdown:
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				klog.Infof("Service stopping")
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				// We need to translate this request into a signal that can be handled by the signal handler
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				// handling shutdowns normally (currently apiserver/pkg/server/signal.go).
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				// If we do not do this, our main threads won't be notified of the upcoming shutdown.
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				// Since Windows services do not use any console, we cannot simply generate a CTRL_BREAK_EVENT
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				// but need a dedicated notification mechanism.
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				graceful := server.RequestShutdown()
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				// Free up the control handler and let us terminate as gracefully as possible.
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				// If that takes too long, the service controller will kill the remaining threads.
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				// As per https://docs.microsoft.com/en-us/windows/desktop/services/service-control-handler-function
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				s <- svc.Status{State: svc.StopPending}
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				// If we cannot exit gracefully, we really only can exit our process, so atleast the
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				// service manager will think that we gracefully exited. At the time of writing this comment this is
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				// needed for applications that do not use signals (e.g. kube-proxy)
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				if !graceful {
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					go func() {
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						// Ensure the SCM was notified (The operation above (send to s) was received and communicated to the
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						// service control manager - so it doesn't look like the service crashes)
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						time.Sleep(1 * time.Second)
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						os.Exit(0)
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					}()
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				}
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				break Loop
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			}
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		}
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	}
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	return false, 0
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}
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