[Elastic Agent] Fix Windows powershell install service script (#20203)

* Fix install service script.

* Add changelog.

* Register as a Windows service and fix issue with reader closer.

* Fix install service script.

* Add changelog.

dev-tools/packaging/templates/windows/install-service-elastic-agent.ps1.tmpl

@@ -1,3 +1,5 @@
+$ErrorActionPreference = "Stop"
+
 # Delete and stop the service if it already exists.
 if (Get-Service {{.BeatName}} -ErrorAction SilentlyContinue) {
   $service = Get-WmiObject -Class Win32_Service -Filter "name='{{.BeatName}}'"
@@ -13,8 +15,5 @@ New-Service -name {{.BeatName}} `
   -displayName {{.BeatName | title}} `
   -binaryPathName "`"$workdir\{{.BeatName}}.exe`" --path.home `"$workdir`" --path.data  `"$workdir\data`" run"
 
-# Attempt to set the service to delayed start using sc config.
-Try {
-  Start-Process -FilePath sc.exe -ArgumentList 'config {{.BeatName}} start= delayed-auto'
-}
-Catch { Write-Host -f red "An error occured setting the service to delayed start." }
+# Start the new service.
+Start-Service -name {{.BeatName}}

x-pack/elastic-agent/CHANGELOG.asciidoc

@@ -55,6 +55,7 @@
 - Fix failing unit tests on windows {pull}20127[20127]
 - Improve GRPC stop to be more relaxed {pull}20118[20118]
 - Prevent closing closed reader {pull}20214[20214]
+- Fix Windows service installation script {pull}20203[20203]
 
 ==== New features
 

x-pack/elastic-agent/pkg/agent/application/info/agent_id.go

@@ -86,6 +86,7 @@ func getInfoFromStore(s ioStore) (*persistentAgentInfo, error) {
 		return nil, err
 	}
 
+	// reader is closed by this function
 	cfg, err := config.NewConfigFrom(reader)
 	if err != nil {
 		return nil, errors.New(err,
@@ -126,6 +127,7 @@ func updateAgentInfo(s ioStore, agentInfo *persistentAgentInfo) error {
 		return err
 	}
 
+	// reader is closed by this function
 	cfg, err := config.NewConfigFrom(reader)
 	if err != nil {
 		return errors.New(err, fmt.Sprintf("fail to read configuration %s for the agent", agentConfigFile),

x-pack/elastic-agent/pkg/agent/cmd/run.go

@@ -5,13 +5,16 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
 	"os"
 	"os/signal"
 	"syscall"
 
 	"github.com/spf13/cobra"
 
+	"github.com/elastic/beats/v7/libbeat/service"
+
 	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/application"
 	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/application/paths"
 	"github.com/elastic/beats/v7/x-pack/elastic-agent/pkg/agent/configuration"
@@ -57,12 +60,20 @@ func run(flags *globalFlags, streams *cli.IOStreams) error {
 		return err
 	}
 
+	// Windows: Mark service as stopped.
+	// After this is run, the service is considered by the OS to be stopped.
+	// This must be the first deferred cleanup task (last to execute).
+	defer service.NotifyTermination()
+
 	locker := application.NewAppLocker(paths.Data())
 	if err := locker.TryLock(); err != nil {
 		return err
 	}
 	defer locker.Unlock()
 
+	service.BeforeRun()
+	defer service.Cleanup()
+
 	app, err := application.New(logger, pathConfigFile)
 	if err != nil {
 		return err
@@ -72,11 +83,24 @@ func run(flags *globalFlags, streams *cli.IOStreams) error {
 		return err
 	}
 
+	// register as a service
+	stop := make(chan bool)
+	_, cancel := context.WithCancel(context.Background())
+	var stopBeat = func() {
+		close(stop)
+	}
+	service.HandleSignals(stopBeat, cancel)
+
 	// listen for kill signal
 	signals := make(chan os.Signal, 1)
 	signal.Notify(signals, syscall.SIGINT, syscall.SIGKILL, syscall.SIGTERM, syscall.SIGQUIT)
 
-	<-signals
+	select {
+	case <-stop:
+		break
+	case <-signals:
+		break
+	}
 
 	return app.Stop()
 }