supervise: refactor to use one HTTP handler

supervise.go

@@ -105,6 +105,15 @@ func (s *service) Process() *os.Process {
 	return s.process
 }
 
+func (s *service) Signal(signal syscall.Signal) error {
+	s.processMu.RLock()
+	defer s.processMu.RUnlock()
+	if s.process != nil {
+		return s.process.Signal(signal)
+	}
+	return nil // no process, nothing to signal
+}
+
 func (s *service) setProcess(p *os.Process) {
 	s.processMu.Lock()
 	defer s.processMu.Unlock()
@@ -195,35 +204,11 @@ func supervise(s *service) {
 	}
 }
 
-func redirectToStatus(w http.ResponseWriter, r *http.Request, path string) {
+var services []*service
-	// StatusSeeOther will result in a GET request for the
-	// redirect location
-	u, _ := url.Parse("/status")
-	u.RawQuery = url.Values{
-		"path": []string{path},
-	}.Encode()
-	http.Redirect(w, r, u.String(), http.StatusSeeOther)
-}
 
 // killSupervisedServices is called before rebooting when upgrading, allowing
 // processes to terminate in an orderly fashion.
-var killSupervisedServices = func() {}
+func killSupervisedServices() {
-
-func superviseServices(services []*service) {
-	for _, s := range services {
-		go supervise(s)
-	}
-
-	findSvc := func(path string) *service {
-		for _, s := range services {
-			if s.cmd.Path == path {
-				return s
-			}
-		}
-		return nil
-	}
-
-	killSupervisedServices = func() {
 	for _, s := range services {
 		if s.Stopped() {
 			continue
@@ -235,39 +220,36 @@ func superviseServices(services []*service) {
 			p.Signal(syscall.SIGTERM)
 		}
 	}
+}
+
+func findSvc(path string) *service {
+	for _, s := range services {
+		if s.cmd.Path == path {
+			return s
+		}
+	}
+	return nil
+}
+
+func restart(s *service, signal syscall.Signal) error {
+	if s.Stopped() {
+		s.setStopped(false) // start process in next supervise iteration
+		return nil
 	}
 
-	http.HandleFunc("/stop", func(w http.ResponseWriter, r *http.Request) {
+	return s.Signal(signal) // kill to restart
-		if r.Method != http.MethodPost {
+}
-			http.Error(w, "expected a POST request", http.StatusBadRequest)
-			return
-		}
 
-		path := r.FormValue("path")
+func stop(s *service, signal syscall.Signal) error {
-
+	if s.Stopped() {
-		s := findSvc(path)
+		return nil // nothing to do
-		if s == nil || s.Stopped() {
-			redirectToStatus(w, r, path)
-			return
 	}
 
 	s.setStopped(true)
+	return s.Signal(signal)
+}
 
-		p := s.Process()
+func stopstartHandler(w http.ResponseWriter, r *http.Request) {
-		if p == nil {
-			redirectToStatus(w, r, path)
-			return
-		}
-
-		if err := p.Signal(syscall.SIGTERM); err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
-
-		redirectToStatus(w, r, path)
-	})
-
-	http.HandleFunc("/restart", func(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
 		http.Error(w, "expected a POST request", http.StatusBadRequest)
 		return
@@ -279,30 +261,36 @@ func superviseServices(services []*service) {
 	}
 
 	path := r.FormValue("path")
-
 	s := findSvc(path)
 	if s == nil {
-			redirectToStatus(w, r, path)
+		http.Error(w, "no such service", http.StatusNotFound)
 		return
 	}
-
+	var err error
-		if s.Stopped() {
+	if r.URL.Path == "/restart" {
-			s.setStopped(false)
+		err = restart(s, signal)
-			redirectToStatus(w, r, path)
+	} else {
-			return
+		err = stop(s, signal)
 	}
-
+	if err != nil {
-		p := s.Process()
-		if p == nil {
-			redirectToStatus(w, r, path)
-			return
-		}
-
-		if err := p.Signal(signal); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-
+	// StatusSeeOther will result in a GET request for the
-		redirectToStatus(w, r, path)
+	// redirect location
-	})
+	u, _ := url.Parse("/status")
+	u.RawQuery = url.Values{
+		"path": []string{path},
+	}.Encode()
+	http.Redirect(w, r, u.String(), http.StatusSeeOther)
+}
+
+func superviseServices(svc []*service) {
+	services = svc
+	for _, s := range services {
+		go supervise(s)
+	}
+
+	http.HandleFunc("/stop", stopstartHandler)
+	http.HandleFunc("/restart", stopstartHandler)
 }