add validation logs for configured Logger/Audit HTTP targets (#10274)

extra logs in-case of misconfiguration of audit/logger targets

cmd/logger/targets.go

@@ -20,14 +20,33 @@ package logger
 // a single log entry and Send it to the log target
 //   e.g. Send the log to a http server
 type Target interface {
+	Validate() error
 	Send(entry interface{}, errKind string) error
 }
 
 // Targets is the set of enabled loggers
 var Targets = []Target{}
 
+// AuditTargets is the list of enabled audit loggers
+var AuditTargets = []Target{}
+
+// AddAuditTarget adds a new audit logger target to the
+// list of enabled loggers
+func AddAuditTarget(t Target) error {
+	if err := t.Validate(); err != nil {
+		return err
+	}
+
+	AuditTargets = append(AuditTargets, t)
+	return nil
+}
+
 // AddTarget adds a new logger target to the
 // list of enabled loggers
-func AddTarget(t Target) {
+func AddTarget(t Target) error {
+	if err := t.Validate(); err != nil {
+		return err
+	}
 	Targets = append(Targets, t)
+	return nil
 }