Refactor collectors

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

pkg/initiate/initiate.go

@@ -0,0 +1,72 @@
+// Package initiate allows us to initiate Time Sensitive components (Like registering the windows service) as early as possible in the startup process
+package initiate
+
+import (
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/windows/svc"
+	"golang.org/x/sys/windows/svc/eventlog"
+)
+
+const (
+	serviceName = "windows_exporter"
+)
+
+type windowsExporterService struct {
+	stopCh chan<- bool
+}
+
+var logger *eventlog.Log
+
+func (s *windowsExporterService) Execute(_ []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {
+	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown
+	changes <- svc.Status{State: svc.StartPending}
+	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
+loop:
+	for {
+		select {
+		case c := <-r:
+			switch c.Cmd {
+			case svc.Interrogate:
+				changes <- c.CurrentStatus
+			case svc.Stop, svc.Shutdown:
+				_ = logger.Info(100, "Service Stop Received")
+				changes <- svc.Status{State: svc.StopPending}
+				break loop
+			default:
+				_ = logger.Error(102, fmt.Sprintf("unexpected control request #%d", c))
+			}
+		}
+	}
+	s.stopCh <- true
+	return
+}
+
+var StopCh = make(chan bool)
+
+func init() {
+	isService, err := svc.IsWindowsService()
+	if err != nil {
+		logger, err = eventlog.Open("windows_exporter")
+		if err != nil {
+			os.Exit(2)
+		}
+		_ = logger.Error(102, fmt.Sprintf("Failed to detect service: %v", err))
+		os.Exit(1)
+	}
+
+	if isService {
+		logger, err = eventlog.Open("windows_exporter")
+		if err != nil {
+			os.Exit(2)
+		}
+		_ = logger.Info(100, "Attempting to start exporter service")
+		go func() {
+			err = svc.Run(serviceName, &windowsExporterService{stopCh: StopCh})
+			if err != nil {
+				_ = logger.Error(102, fmt.Sprintf("Failed to start service: %v", err))
+			}
+		}()
+	}
+}