Revert "refactor fleet mode detection and storage" (#41151)

* Revert "refactor fleet mode detection and storage (#40667)"

This reverts commit 3309620.

* fix import

libbeat/cfgfile/cfgfile.go

@@ -112,8 +112,6 @@ func GetDefaultCfgfile() string {
 }
 
 // HandleFlags adapts default config settings based on command line flags.
-// This also stores if -E management.enabled=true was set on command line
-// to determine if running the Beat under agent.
 func HandleFlags() error {
 	// default for the home path is the binary location
 	home, err := filepath.Abs(filepath.Dir(os.Args[0]))
@@ -131,27 +129,6 @@ func HandleFlags() error {
 		common.PrintConfigDebugf(overwrites, "CLI setting overwrites (-E flag):")
 	}
 
-	// Enable check to see if beat is running under Agent
-	// This is stored in a package so the modules which don't have
-	// access to the config can check this value.
-	type management struct {
-		Enabled bool `config:"management.enabled"`
-	}
-	var managementSettings management
-	cfgFlag := flag.Lookup("E")
-	if cfgFlag == nil {
-		fleetmode.SetAgentMode(false)
-		return nil
-	}
-	cfgObject, _ := cfgFlag.Value.(*config.SettingsFlag)
-	cliCfg := cfgObject.Config()
-
-	err = cliCfg.Unpack(&managementSettings)
-	if err != nil {
-		fleetmode.SetAgentMode(false)
-		return nil //nolint:nilerr // unpacking failing isn't an error for this case
-	}
-	fleetmode.SetAgentMode(managementSettings.Enabled)
 	return nil
 }
 

libbeat/common/fleetmode/fleet_mode.go

@@ -17,18 +17,33 @@
 
 package fleetmode
 
-var managementEnabled bool
-
-// SetAgentMode stores if the Beat is running under Elastic Agent.
-// Normally this is called when the command line flags are parsed.
-// This is stored as a package level variable because some components
-// (like filebeat/metricbeat modules) don't have access to the
-// configuration information to determine this on their own.
-func SetAgentMode(enabled bool) {
-	managementEnabled = enabled
-}
+import (
+	"flag"
+
+	"github.com/elastic/elastic-agent-libs/config"
+)
 
-// Enabled returns true if the Beat is running under Elastic Agent.
+// Enabled checks to see if filebeat/metricbeat is running under Agent
+// The management setting is stored in the main Beat runtime object, but we can't see that from a module
+// So instead we check the CLI flags, since Agent starts filebeat/metricbeat with "-E", "management.enabled=true"
 func Enabled() bool {
-	return managementEnabled
+	type management struct {
+		Enabled bool `config:"management.enabled"`
+	}
+	var managementSettings management
+
+	cfgFlag := flag.Lookup("E")
+	if cfgFlag == nil {
+		return false
+	}
+
+	cfgObject, _ := cfgFlag.Value.(*config.SettingsFlag)
+	cliCfg := cfgObject.Config()
+
+	err := cliCfg.Unpack(&managementSettings)
+	if err != nil {
+		return false
+	}
+
+	return managementSettings.Enabled
 }