Revert "Don't register cfgfile flags on flag.CommandLine in `func i…

…nit()`" (#41152)

* Revert "Don't register cfgfile flags on `flag.CommandLine` in `func init()` (…"

This reverts commit 07360ca.

* linter fixes

libbeat/cfgfile/cfgfile.go

@@ -18,11 +18,9 @@
 package cfgfile
 
 import (
-	"flag"
 	"fmt"
 	"os"
 	"path/filepath"
-	"sync"
 
 	"github.com/elastic/beats/v7/libbeat/common"
 	"github.com/elastic/beats/v7/libbeat/common/fleetmode"
@@ -35,10 +33,8 @@ var (
 	// The default config cannot include the beat name as it is not initialized
 	// when this variable is created. See ChangeDefaultCfgfileFlag which should
 	// be called prior to flags.Parse().
-	commandLine     flag.FlagSet
-	commandLineOnce sync.Once
-	configfiles     = config.StringArrFlag(&commandLine, "c", "beat.yml", "Configuration file, relative to path.config")
-	overwrites      = config.SettingFlag(&commandLine, "E", "Configuration overwrite")
+	configfiles = config.StringArrFlag(nil, "c", "beat.yml", "Configuration file, relative to path.config")
+	overwrites  = config.SettingFlag(nil, "E", "Configuration overwrite")
 
 	// Additional default settings, that must be available for variable expansion
 	defaults = config.MustNewConfigFrom(map[string]interface{}{
@@ -58,7 +54,7 @@ var (
 func init() {
 	// add '-path.x' options overwriting paths in 'overwrites' config
 	makePathFlag := func(name, usage string) *string {
-		return config.ConfigOverwriteFlag(&commandLine, overwrites, name, name, "", usage)
+		return config.ConfigOverwriteFlag(nil, overwrites, name, name, "", usage)
 	}
 
 	homePath = makePathFlag("path.home", "Home path")
@@ -67,17 +63,6 @@ func init() {
 	makePathFlag("path.logs", "Logs path")
 }
 
-// InitFlags is for explicitly initializing the flags.
-// It may get called repeatedly for different flagsets, but not
-// twice for the same one.
-func InitFlags() {
-	commandLineOnce.Do(func() {
-		commandLine.VisitAll(func(f *flag.Flag) {
-			flag.CommandLine.Var(f.Value, f.Name, f.Usage)
-		})
-	})
-}
-
 // OverrideChecker checks if a config should be overwritten.
 type OverrideChecker func(*config.C) bool
 

libbeat/cmd/instance/beat_integration_test.go

@@ -27,7 +27,6 @@ import (
 	"time"
 
 	"github.com/elastic/beats/v7/libbeat/beat"
-	"github.com/elastic/beats/v7/libbeat/cfgfile"
 	"github.com/elastic/beats/v7/libbeat/cmd/instance"
 	"github.com/elastic/beats/v7/libbeat/mock"
 	"github.com/elastic/elastic-agent-libs/config"
@@ -79,7 +78,6 @@ func (mb mockbeat) Stop() {
 }
 
 func TestMonitoringNameFromConfig(t *testing.T) {
-
 	mockBeat := mockbeat{
 		done:     make(chan struct{}),
 		initDone: make(chan struct{}),
@@ -93,8 +91,6 @@ func TestMonitoringNameFromConfig(t *testing.T) {
 	go func() {
 		defer wg.Done()
 
-		// Initialize cfgfile flags
-		cfgfile.InitFlags()
 		// Set the configuration file path flag so the beat can read it
 		_ = flag.Set("c", "testdata/mockbeat.yml")
 		_ = instance.Run(mock.Settings, func(_ *beat.Beat, _ *config.C) (beat.Beater, error) {
@@ -118,10 +114,15 @@ func TestMonitoringNameFromConfig(t *testing.T) {
 	if err != nil {
 		t.Fatalf("error creating request: %v", err)
 	}
+
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		t.Fatalf("calling state endpoint: %v", err)
 	}
+
+	if err != nil {
+		t.Fatal("calling state endpoint: ", err.Error())
+	}
 	defer resp.Body.Close()
 
 	beatName := struct {

libbeat/cmd/root.go

@@ -81,9 +81,6 @@ func GenRootCmdWithSettings(beatCreator beat.Creator, settings instance.Settings
 		panic(fmt.Errorf("failed to set default config file path: %w", err))
 	}
 
-	// Initialize the configuration flags.
-	cfgfile.InitFlags()
-
 	// must be updated prior to CLI flag handling.
 
 	rootCmd.RunCmd = genRunCmd(settings, beatCreator)