Use consts for backend config

x-pack/auditbeat/processors/add_session_metadata/add_session_metadata.go

@@ -56,10 +56,10 @@ func New(cfg *config.C) (beat.Processor, error) {
 	logger.Debugf("backfilled %d processes", len(backfilledPIDs))
 
 	switch c.Backend {
-	case "auto":
+	case BackendAuto:
 		// "auto" always uses ebpf, as it's currently the only backend
 		fallthrough
-	case "ebpf":
+	case BackendEbpf:
 		p, err := ebpf_provider.NewProvider(ctx, logger, db)
 		if err != nil {
 			return nil, fmt.Errorf("failed to create ebpf provider: %w", err)

x-pack/auditbeat/processors/add_session_metadata/config.go

@@ -2,20 +2,25 @@
 // or more contributor license agreements. Licensed under the Elastic License;
 // you may not use this file except in compliance with the Elastic License.
 
-//go:build linux
-
 package add_session_metadata
 
+type Backend string
+
+const (
+	BackendAuto Backend = "auto"
+	BackendEbpf Backend = "ebpf"
+)
+
 // Config for add_session_metadata processor.
 type Config struct {
-	Backend       string `config:"backend"`
-	ReplaceFields bool   `config:"replace_fields"`
-	PidField      string `config:"pid_field"`
+	Backend       Backend `config:"backend"`
+	ReplaceFields bool    `config:"replace_fields"`
+	PidField      string  `config:"pid_field"`
 }
 
 func defaultConfig() Config {
 	return Config{
-		Backend:       "auto",
+		Backend:       BackendAuto,
 		ReplaceFields: false,
 		PidField:      "process.pid",
 	}