cmd/dockerd/service_windows.go
package main
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"time"
"github.com/containerd/log"
"github.com/spf13/pflag"
"golang.org/x/sys/windows"
"golang.org/x/sys/windows/svc"
"golang.org/x/sys/windows/svc/debug"
"golang.org/x/sys/windows/svc/eventlog"
"golang.org/x/sys/windows/svc/mgr"
)
var (
flServiceName *string
flRegisterService *bool
flUnregisterService *bool
flRunService *bool
oldStderr windows.Handle
panicFile *os.File
service *handler
)
const (
// These should match the values in event_messages.mc.
eventInfo = 1
eventWarn = 1
eventError = 1
eventDebug = 2
eventPanic = 3
eventFatal = 4
eventExtraOffset = 10 // Add this to any event to get a string that supports extended data
)
func installServiceFlags(flags *pflag.FlagSet) {
flServiceName = flags.String("service-name", "docker", "Set the Windows service name")
flRegisterService = flags.Bool("register-service", false, "Register the service and exit")
flUnregisterService = flags.Bool("unregister-service", false, "Unregister the service and exit")
flRunService = flags.Bool("run-service", false, "")
_ = flags.MarkHidden("run-service")
}
type handler struct {
tosvc chan bool
fromsvc chan error
daemonCLI *daemonCLI
}
type etwHook struct {
log *eventlog.Log
}
func (h *etwHook) Levels() []log.Level {
return []log.Level{
log.PanicLevel,
log.FatalLevel,
log.ErrorLevel,
log.WarnLevel,
log.InfoLevel,
log.DebugLevel,
}
}
func (h *etwHook) Fire(e *log.Entry) error {
var (
etype uint16
eid uint32
)
switch e.Level {
case log.PanicLevel:
etype = windows.EVENTLOG_ERROR_TYPE
eid = eventPanic
case log.FatalLevel:
etype = windows.EVENTLOG_ERROR_TYPE
eid = eventFatal
case log.ErrorLevel:
etype = windows.EVENTLOG_ERROR_TYPE
eid = eventError
case log.WarnLevel:
etype = windows.EVENTLOG_WARNING_TYPE
eid = eventWarn
case log.InfoLevel:
etype = windows.EVENTLOG_INFORMATION_TYPE
eid = eventInfo
case log.DebugLevel:
etype = windows.EVENTLOG_INFORMATION_TYPE
eid = eventDebug
default:
return errors.New("unknown level")
}
// If there is additional data, include it as a second string.
exts := ""
if len(e.Data) > 0 {
fs := bytes.Buffer{}
for k, v := range e.Data {
fs.WriteString(k)
fs.WriteByte('=')
fmt.Fprint(&fs, v)
fs.WriteByte(' ')
}
exts = fs.String()[:fs.Len()-1]
eid += eventExtraOffset
}
if h.log == nil {
fmt.Fprintf(os.Stderr, "%s [%s]\n", e.Message, exts)
return nil
}
var (
ss [2]*uint16
err error
)
ss[0], err = windows.UTF16PtrFromString(e.Message)
if err != nil {
return err
}
count := uint16(1)
if exts != "" {
ss[1], err = windows.UTF16PtrFromString(exts)
if err != nil {
return err
}
count++
}
return windows.ReportEvent(h.log.Handle, etype, 0, eid, 0, count, 0, &ss[0], nil)
}
func registerService() error {
p, err := os.Executable()
if err != nil {
return err
}
m, err := mgr.Connect()
if err != nil {
return err
}
defer m.Disconnect()
c := mgr.Config{
ServiceType: windows.SERVICE_WIN32_OWN_PROCESS,
StartType: mgr.StartAutomatic,
ErrorControl: mgr.ErrorNormal,
Dependencies: []string{},
DisplayName: "Docker Engine",
}
// Configure the service to launch with the arguments that were just passed.
args := []string{"--run-service"}
for _, a := range os.Args[1:] {
if a != "--register-service" && a != "--unregister-service" {
args = append(args, a)
}
}
s, err := m.CreateService(*flServiceName, p, c, args...)
if err != nil {
return err
}
defer s.Close()
err = s.SetRecoveryActions(
[]mgr.RecoveryAction{
{Type: mgr.ServiceRestart, Delay: 15 * time.Second},
{Type: mgr.ServiceRestart, Delay: 15 * time.Second},
{Type: mgr.NoAction},
},
uint32(24*time.Hour/time.Second),
)
if err != nil {
return err
}
return eventlog.Install(*flServiceName, p, false, eventlog.Info|eventlog.Warning|eventlog.Error)
}
func unregisterService() error {
m, err := mgr.Connect()
if err != nil {
return err
}
defer m.Disconnect()
s, err := m.OpenService(*flServiceName)
if err != nil {
return err
}
defer s.Close()
eventlog.Remove(*flServiceName)
err = s.Delete()
if err != nil {
return err
}
return nil
}
// initService is the entry point for running the daemon as a Windows
// service. It returns an indication to stop (if registering/un-registering);
// an indication of whether it is running as a service; and an error.
func initService(cli *daemonCLI) (bool, bool, error) {
if *flUnregisterService {
if *flRegisterService {
return true, false, errors.New("--register-service and --unregister-service cannot be used together")
}
return true, false, unregisterService()
}
if *flRegisterService {
return true, false, registerService()
}
if !*flRunService {
return false, false, nil
}
// Check if we're running as a Windows service or interactively.
isService, err := svc.IsWindowsService()
if err != nil {
return false, false, err
}
h := &handler{
tosvc: make(chan bool),
fromsvc: make(chan error),
daemonCLI: cli,
}
var eventLog *eventlog.Log
if isService {
eventLog, err = eventlog.Open(*flServiceName)
if err != nil {
return false, false, err
}
}
log.L.Logger.AddHook(&etwHook{eventLog})
log.L.Logger.SetOutput(io.Discard)
service = h
go func() {
if isService {
err = svc.Run(*flServiceName, h)
} else {
err = debug.Run(*flServiceName, h)
}
h.fromsvc <- err
}()
// Wait for the first signal from the service handler.
err = <-h.fromsvc
if err != nil {
return false, false, err
}
return false, true, nil
}
func (h *handler) started() error {
// This must be delayed until daemonCli initializes Config.Root
err := initPanicFile(filepath.Join(h.daemonCLI.Config.Root, "panic.log"))
if err != nil {
return err
}
h.tosvc <- false
return nil
}
func (h *handler) stopped(err error) {
log.G(context.TODO()).Debugf("Stopping service: %v", err)
h.tosvc <- err != nil
<-h.fromsvc
}
func (h *handler) Execute(_ []string, r <-chan svc.ChangeRequest, s chan<- svc.Status) (bool, uint32) {
s <- svc.Status{State: svc.StartPending, Accepts: 0}
// Unblock initService()
h.fromsvc <- nil
// Wait for initialization to complete.
failed := <-h.tosvc
if failed {
log.G(context.TODO()).Debug("Aborting service start due to failure during initialization")
return true, 1
}
s <- svc.Status{State: svc.Running, Accepts: svc.AcceptStop | svc.AcceptShutdown | svc.AcceptParamChange}
log.G(context.TODO()).Debug("Service running")
Loop:
for {
select {
case failed = <-h.tosvc:
break Loop
case c := <-r:
switch c.Cmd {
case svc.ParamChange:
h.daemonCLI.reloadConfig()
case svc.Interrogate:
s <- c.CurrentStatus
case svc.Stop, svc.Shutdown:
s <- svc.Status{State: svc.StopPending, Accepts: 0}
h.daemonCLI.stop()
}
}
}
removePanicFile()
if failed {
return true, 1
}
return false, 0
}
func initPanicFile(path string) error {
var err error
panicFile, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o200)
if err != nil {
return err
}
st, err := panicFile.Stat()
if err != nil {
return err
}
// If there are contents in the file already, move the file out of the way
// and replace it.
if st.Size() > 0 {
panicFile.Close()
os.Rename(path, path+".old")
panicFile, err = os.Create(path)
if err != nil {
return err
}
}
// Update STD_ERROR_HANDLE to point to the panic file so that Go writes to
// it when it panics. Remember the old stderr to restore it before removing
// the panic file.
h, err := windows.GetStdHandle(windows.STD_ERROR_HANDLE)
if err != nil {
return err
}
oldStderr = h
err = windows.SetStdHandle(windows.STD_ERROR_HANDLE, windows.Handle(panicFile.Fd()))
if err != nil {
return err
}
// Reset os.Stderr to the panic file (so fmt.Fprintf(os.Stderr,...) actually gets redirected)
os.Stderr = os.NewFile(panicFile.Fd(), "/dev/stderr")
// Force threads that panic to write to stderr (the panicFile handle now), otherwise it will go into the ether
log.L.Logger.SetOutput(os.Stderr)
return nil
}
func removePanicFile() {
if st, err := panicFile.Stat(); err == nil {
if st.Size() == 0 {
windows.SetStdHandle(windows.STD_ERROR_HANDLE, oldStderr)
panicFile.Close()
os.Remove(panicFile.Name())
}
}
}