Generate custom service code for Windows (#75)

* update main to include windows service code

* use main version from tag 0.35.0

* update main function

* align with upstream v0.36.0 tag

* dummy change to trigger build

* Revert "dummy change to trigger build"

This reverts commit 629d499461da2d2c240bf1e495b5fe0558e3547f.

internal/builder/main.go

@@ -69,6 +69,14 @@ func Generate(cfg Config) error {
 			"main.go",
 			scaffold.Main,
 		},
+		{
+			"main_others.go",
+			scaffold.MainOthers,
+		},
+		{
+			"main_windows.go",
+			scaffold.MainWindows,
+		},
 		// components.go
 		{
 			"components.go",

internal/scaffold/main.go

@@ -35,6 +35,7 @@ const Main = `
 package main
 
 import (
+	"fmt"
 	"log"
 
 	"go.opentelemetry.io/collector/component"
@@ -53,14 +54,113 @@ func main() {
 		Version:  "{{ .Distribution.Version }}",
 	}
 
-	app, err := service.New(service.CollectorSettings{BuildInfo: info, Factories: factories})
+	if err := run(service.CollectorSettings{BuildInfo: info, Factories: factories}); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func runInteractive(params service.CollectorSettings) error {
+	app, err := service.New(params)
 	if err != nil {
-		log.Fatalf("failed to construct the application: %v", err)
+		return fmt.Errorf("failed to construct the collector server: %w", err)
 	}
 
 	cmd := service.NewCommand(app)
 	if err = cmd.Execute(); err != nil {
-		log.Fatalf("application run finished with error: %v", err)
+		log.Fatalf("collector server run finished with error: %v", err)
+	}
+
+	return nil
+}
+`
+
+const MainOthers = `
+// Copyright The OpenTelemetry 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.
+
+//go:build !windows
+// +build !windows
+
+package main
+
+import "go.opentelemetry.io/collector/service"
+
+func run(params service.CollectorSettings) error {
+	return runInteractive(params)
+}
+`
+
+const MainWindows = `
+// Copyright The OpenTelemetry 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.
+
+//go:build windows
+// +build windows
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"go.opentelemetry.io/collector/service"
+	"golang.org/x/sys/windows/svc"
+)
+
+func run(params service.CollectorSettings) error {
+	if useInteractiveMode, err := checkUseInteractiveMode(); err != nil {
+		return err
+	} else if useInteractiveMode {
+		return runInteractive(params)
+	} else {
+		return runService(params)
+	}
+}
+
+func checkUseInteractiveMode() (bool, error) {
+	// If environment variable NO_WINDOWS_SERVICE is set with any value other
+	// than 0, use interactive mode instead of running as a service. This should
+	// be set in case running as a service is not possible or desired even
+	// though the current session is not detected to be interactive
+	if value, present := os.LookupEnv("NO_WINDOWS_SERVICE"); present && value != "0" {
+		return true, nil
+	}
+
+	if isInteractiveSession, err := svc.IsAnInteractiveSession(); err != nil {
+		return false, fmt.Errorf("failed to determine if we are running in an interactive session %w", err)
+	} else {
+		return isInteractiveSession, nil
 	}
 }
+
+func runService(params service.CollectorSettings) error {
+	// do not need to supply service name when startup is invoked through Service Control Manager directly
+	if err := svc.Run("", service.NewWindowsService(params)); err != nil {
+		return fmt.Errorf("failed to start collector server: %w", err)
+	}
+
+	return nil
+}
 `