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Use dedicated zapcore.Core for Windows service
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Ryan Fitzpatrick committed May 20, 2021
1 parent f7674b2 commit 6546214
Showing 1 changed file with 62 additions and 21 deletions.
83 changes: 62 additions & 21 deletions service/application_windows.go
Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,7 @@ func (s *WindowsService) Execute(args []string, requests <-chan svc.ChangeReques

func (s *WindowsService) start(elog *eventlog.Log, appErrorChannel chan error) error {
var err error
s.app, err = newWithEventViewerLoggingHook(s.params, elog)
s.app, err = newWithWindowsEventLogCore(s.params, elog)
if err != nil {
return err
}
Expand Down Expand Up @@ -120,28 +120,69 @@ func openEventLog(serviceName string) (*eventlog.Log, error) {
return elog, nil
}

func newWithEventViewerLoggingHook(params Parameters, elog *eventlog.Log) (*Application, error) {
func newWithWindowsEventLogCore(params Parameters, elog *eventlog.Log) (*Application, error) {
params.LoggingOptions = append(
params.LoggingOptions,
zap.Hooks(func(entry zapcore.Entry) error {
msg := fmt.Sprintf("%v\r\n\r\nStack Trace:\r\n%v", entry.Message, entry.Stack)

switch entry.Level {
case zapcore.FatalLevel, zapcore.PanicLevel, zapcore.DPanicLevel:
// golang.org/x/sys/windows/svc/eventlog does not support Critical level event logs
return elog.Error(3, msg)
case zapcore.ErrorLevel:
return elog.Error(3, msg)
case zapcore.WarnLevel:
return elog.Warning(2, msg)
case zapcore.InfoLevel:
return elog.Info(1, msg)
}

// ignore Debug level logs
return nil
}),
zap.WrapCore(withWindowsCore(elog)),
)

return New(params)
}

var _ zapcore.Core = (*windowsEventLogCore)(nil)

type windowsEventLogCore struct {
core zapcore.Core
elog *eventlog.Log
encoder zapcore.Encoder
}

func (w windowsEventLogCore) Enabled(level zapcore.Level) bool {
return w.core.Enabled(level)
}

func (w windowsEventLogCore) With(fields []zapcore.Field) zapcore.Core {
return withWindowsCore(w.elog)(w.core.With(fields))
}

func (w windowsEventLogCore) Check(ent zapcore.Entry, ce *zapcore.CheckedEntry) *zapcore.CheckedEntry {
if w.Enabled(ent.Level) {
return ce.AddCore(ent, w)
}
return ce
}

func (w windowsEventLogCore) Write(ent zapcore.Entry, fields []zapcore.Field) error {
buf, err := w.encoder.EncodeEntry(ent, fields)
if err != nil {
w.elog.Warning(2, fmt.Sprintf("failed encoding log entry %v\r\n", err))
return err
}
msg := buf.String()
buf.Free()

switch ent.Level {
case zapcore.FatalLevel, zapcore.PanicLevel, zapcore.DPanicLevel:
// golang.org/x/sys/windows/svc/eventlog does not support Critical level event logs
return w.elog.Error(3, msg)
case zapcore.ErrorLevel:
return w.elog.Error(3, msg)
case zapcore.WarnLevel:
return w.elog.Warning(2, msg)
case zapcore.InfoLevel:
return w.elog.Info(1, msg)
}
// We would not be here if debug were disabled so log as info to not drop.
return w.elog.Info(1, msg)
}

func (w windowsEventLogCore) Sync() error {
return w.core.Sync()
}

func withWindowsCore(elog *eventlog.Log) func(zapcore.Core) zapcore.Core {
return func(core zapcore.Core) zapcore.Core {
encoderConfig := zap.NewProductionEncoderConfig()
encoderConfig.LineEnding = "\r\n"
return windowsEventLogCore{core, elog, zapcore.NewConsoleEncoder(encoderConfig)}
}
}

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