chore: move exporter binary to cmd package (#1768)

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

internal/windowsservice/init.go

@@ -0,0 +1,60 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package windowsservice
+
+import (
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/svc"
+)
+
+var (
+	// IsService is true if the exporter is running as a Windows service.
+	IsService bool
+	// ExitCodeCh is a channel to send the exit code return from the [github.com/prometheus-community/windows_exporter/cmd/windows_exporter] function to the service manager.
+	ExitCodeCh = make(chan int)
+
+	// StopCh is a channel to send a signal to the service manager that the service is stopping.
+	StopCh = make(chan struct{})
+)
+
+//nolint:gochecknoinits // An init function is required to communicate with the Windows service manager early in the program.
+func init() {
+	var err error
+
+	IsService, err = svc.IsWindowsService()
+	if err != nil {
+		if err := logToEventToLog(windows.EVENTLOG_ERROR_TYPE, fmt.Sprintf("failed to detect service: %v", err)); err != nil {
+			os.Exit(2)
+		}
+
+		os.Exit(1)
+	}
+
+	if !IsService {
+		return
+	}
+
+	if err := logToEventToLog(windows.EVENTLOG_INFORMATION_TYPE, "attempting to start exporter service"); err != nil {
+		os.Exit(2)
+	}
+
+	go func() {
+		if err := svc.Run(serviceName, &windowsExporterService{}); err != nil {
+			_ = logToEventToLog(windows.EVENTLOG_ERROR_TYPE, fmt.Sprintf("failed to start service: %v", err))
+		}
+	}()
+}