Create custom Windows Event Source in Go

eventlog.go

// +build windows

package main

import (
	"errors"
	"golang.org/x/sys/windows/registry"
	"golang.org/x/sys/windows/svc/eventlog"
)

const eventLogKeyName = `SYSTEM\CurrentControlSet\Services\EventLog`

// InstallCustomLog creates a custom event log under Microsoft Event Viewer.
func InstallCustomLog(name string, src string, eventsSupported uint32) error {
	k, err := createSubKey(registry.LOCAL_MACHINE, eventLogKeyName, name)
	if err != nil {
		return errors.New(name + " subkey could not be created")
	}
	defer k.Close()

	err = k.SetDWordValue("TypesSupported", eventsSupported)
	if err != nil {
		return errors.New("TypesSupported could not be created")
	}

	lk, err := createSubKey(registry.LOCAL_MACHINE, eventLogKeyName + `\` + name, name)
	if err != nil {
		return errors.New(name + " " + name + " subkey could not be created")
	}
	defer lk.Close()

	err = lk.SetExpandStringValue("EventMessageFile", "C:\\Windows\\Microsoft.NET\\Framework\\v4.0.30319\\EventLogMessages.dll")

	if err != nil {
		return errors.New("EventMessageFile")
	}

	sk, err := createSubKey(registry.LOCAL_MACHINE, eventLogKeyName + `\` + name, src)
	if err != nil {
		return err
	}
	defer sk.Close()

	err = sk.SetExpandStringValue("EventMessageFile", "C:\\Windows\\Microsoft.NET\\Framework\\v4.0.30319\\EventLogMessages.dll")
	if err != nil {
		return err
	}

	if err != nil {
		return err
	}
	return nil
}

// RemoveCustomLog deletes all registry elements installed by the correspondent InstallCustomLog.
func RemoveCustomLog(name string, src string) error {
	appkey, err := registry.OpenKey(registry.LOCAL_MACHINE, eventLogKeyName + `\` + name, registry.SET_VALUE)
	if err != nil {
		return err
	}
	defer appkey.Close()
	err = registry.DeleteKey(appkey, name)
	if err != nil {
		return err
	}
	err = registry.DeleteKey(appkey, src)
	if err != nil {
		return err
	}
	key, err := registry.OpenKey(registry.LOCAL_MACHINE, eventLogKeyName, registry.SET_VALUE)
	if err != nil {
		return err
	}
	defer key.Close()
	return registry.DeleteKey(key, name)
}

func createSubKey(key registry.Key, path string, keyName string) (registry.Key, error) {
	k, err := registry.OpenKey(key, path, registry.CREATE_SUB_KEY)
	if err != nil {
		return k, errors.New(path + " path could not be opened")
	}
	defer k.Close()
	sk, alreadyExist, err := registry.CreateKey(key, path + `\` + keyName, registry.SET_VALUE)
	if err != nil {
		return sk, errors.New(keyName + " key could not be created")
	}
	if alreadyExist {
		return sk, errors.New(path + `\` + keyName + " registry key already exists")
	}
	return sk, nil
}

Use like so:

import (
	"github.com/sirupsen/logrus"
	"github.com/freman/eventloghook"
)

// Sets up custom event log
func SetupEventLog(log *logrus.Logger) {
	const supports = eventlog.Error | eventlog.Warning | eventlog.Info
	svcName := "YourService"

	err := RemoveCustomLog(svcName + "Log", svcName + "Source")
	if err != nil {
		log.Infof("Remove failed: %s", err)
	}

	err = InstallCustomLog(svcName + "Log", svcName + "Source", supports)
	if err != nil {
		log.Infof("Install failed: %s", err)
	}

	l, err := eventlog.Open(svcName + "Log")
	if err != nil {
		log.Infof("Open failed: %s", err)
	}

	l.Info(1, "Setup log")
	log.Hooks.Add(eventloghook.NewHook(l))
}