From 4889b5f340fd722036b124c022d11912b838ba5e Mon Sep 17 00:00:00 2001
From: Tam?s Gul?csi <tgulacsi78@gmail.com>
Date: Thu, 30 Jan 2014 18:57:00 +0100
Subject: [PATCH] Add systemd support

---
 service_linux.go | 119 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 94 insertions(+), 25 deletions(-)

diff --git a/service_linux.go b/service_linux.go
index 6d74e7a..ab98131 100644
--- a/service_linux.go
+++ b/service_linux.go
@@ -1,22 +1,34 @@
 package service
 
 import (
-	"bitbucket.org/kardianos/osext"
 	"fmt"
 	"log/syslog"
 	"os"
 	"os/exec"
 	"os/signal"
 	"text/template"
+
+	"bitbucket.org/kardianos/osext"
 )
 
-func newService(name, displayName, description string) (s *linuxUpstartService, err error) {
-	s = &linuxUpstartService{
+const (
+	initUpstart = initFlavor(iota)
+	initSystemd
+)
+
+func newService(name, displayName, description string) (Service, error) {
+	flavor := initUpstart
+	if _, err := os.Stat("/run/systemd/system"); err == nil {
+		flavor = initSystemd
+	}
+	s := &linuxService{
+		flavor:      flavor,
 		name:        name,
 		displayName: displayName,
 		description: description,
 	}
 
+	var err error
 	s.logger, err = syslog.New(syslog.LOG_INFO, name)
 	if err != nil {
 		return nil, err
@@ -25,13 +37,49 @@ func newService(name, displayName, description string) (s *linuxUpstartService,
 	return s, nil
 }
 
-type linuxUpstartService struct {
+type linuxService struct {
+	flavor                         initFlavor
 	name, displayName, description string
 	logger                         *syslog.Writer
 }
 
-func (s *linuxUpstartService) Install() error {
-	var confPath = "/etc/init/" + s.name + ".conf"
+type initFlavor uint8
+
+func (f initFlavor) String() string {
+	switch f {
+	case initUpstart:
+		return "Upstart"
+	case initSystemd:
+		return "systemd"
+	default:
+		return "unknown"
+	}
+}
+
+func (f initFlavor) ConfigPath(name string) string {
+	switch f {
+	case initUpstart:
+		return "/etc/init/" + name + ".conf"
+	case initSystemd:
+		return "/etc/systemd/system/" + name + ".service"
+	default:
+		return ""
+	}
+}
+
+func (f initFlavor) GetTemplate() *template.Template {
+	var templ string
+	switch f {
+	case initUpstart:
+		templ = upstartScript
+	case initSystemd:
+		templ = systemdScript
+	}
+	return template.Must(template.New(f.String() + "Script").Parse(templ))
+}
+
+func (s *linuxService) Install() error {
+	confPath := s.flavor.ConfigPath(s.name)
 	_, err := os.Stat(confPath)
 	if err == nil {
 		return fmt.Errorf("Init already exists: %s", confPath)
@@ -58,58 +106,66 @@ func (s *linuxUpstartService) Install() error {
 		path,
 	}
 
-	t := template.Must(template.New("upstartScript").Parse(upstartScript))
-	err = t.Execute(f, to)
+	err = s.flavor.GetTemplate().Execute(f, to)
 
 	if err != nil {
 		return err
 	}
 
+	if s.flavor == initSystemd {
+		return exec.Command("systemctl", "daemon-reload").Run()
+	}
+
 	return nil
 }
 
-func (s *linuxUpstartService) Remove() error {
-	return os.Remove("/etc/init/" + s.name + ".conf")
+func (s *linuxService) Remove() error {
+	if s.flavor == initSystemd {
+		exec.Command("systemctl", "disable", s.name+".service").Run()
+	}
+	if err := os.Remove(s.flavor.ConfigPath(s.name)); err != nil {
+		return err
+	}
+	return nil
 }
 
-func (s *linuxUpstartService) Run(onStart, onStop func() error) error {
-	var err error
-
+func (s *linuxService) Run(onStart, onStop func() error) (err error) {
 	err = onStart()
 	if err != nil {
 		return err
 	}
+	defer func() {
+		err = onStop()
+	}()
 
-	var sigChan = make(chan os.Signal, 3)
+	sigChan := make(chan os.Signal, 3)
 
 	signal.Notify(sigChan, os.Interrupt, os.Kill)
 
 	<-sigChan
 
-	return onStop()
+	return nil
 }
 
-func (s *linuxUpstartService) Start() error {
-	cmd := exec.Command("start", s.name)
-	return cmd.Run()
+func (s *linuxService) Start() error {
+	return exec.Command("service", s.name, "start").Run()
 }
 
-func (s *linuxUpstartService) Stop() error {
-	cmd := exec.Command("stop", s.name)
-	return cmd.Run()
+func (s *linuxService) Stop() error {
+	return exec.Command("service", s.name, "stop").Run()
 }
 
-func (s *linuxUpstartService) Error(format string, a ...interface{}) error {
+func (s *linuxService) Error(format string, a ...interface{}) error {
 	return s.logger.Err(fmt.Sprintf(format, a...))
 }
-func (s *linuxUpstartService) Warning(format string, a ...interface{}) error {
+func (s *linuxService) Warning(format string, a ...interface{}) error {
 	return s.logger.Warning(fmt.Sprintf(format, a...))
 }
-func (s *linuxUpstartService) Info(format string, a ...interface{}) error {
+func (s *linuxService) Info(format string, a ...interface{}) error {
 	return s.logger.Info(fmt.Sprintf(format, a...))
 }
 
-var upstartScript = `# {{.Description}}
+const upstartScript = `# {{.Description}}
 
 description     "{{.Display}}"
 
@@ -133,3 +189,16 @@ end script
 # Start
 exec {{.Path}}
 `
+
+const systemdScript = `[Unit]
+Description={{.Description}}
+ConditionFileIsExecutable={{.Path}}
+
+[Service]
+StartLimitInterval=5
+StartLimitBurst=10
+ExecStart={{.Path}}
+
+[Install]
+WantedBy=multi-user.target
+`