allow scaling a mongodb to 0

Author: Olliewer

controllers/validation/validation.go

@@ -143,7 +143,7 @@ func validateArbiterSpec(mdb mdbv1.MongoDBCommunity) error {
 	if mdb.Spec.Arbiters < 0 {
 		return fmt.Errorf("number of arbiters must be greater or equal than 0")
 	}
-	if mdb.Spec.Arbiters >= mdb.Spec.Members {
+	if mdb.Spec.Arbiters >= mdb.Spec.Members && !(mdb.Spec.Members == 0 && mdb.Spec.Arbiter == 0) {
 		return fmt.Errorf("number of arbiters specified (%v) is greater or equal than the number of members in the replicaset (%v). At least one member must not be an arbiter", mdb.Spec.Arbiters, mdb.Spec.Members)
 	}