allow single node deployments

cluster/validation.go

@@ -71,15 +71,6 @@ func validateHostsOptions(c *Cluster) error {
 				return fmt.Errorf("Role [%s] for host (%d) is not recognized", role, i+1)
 			}
 		}
-		k := 0
-		for _, role := range host.Role {
-			if role == services.ControlRole || role == services.WorkerRole {
-				k++
-			}
-		}
-		if k > 1 {
-			return fmt.Errorf("Host (%d) can't contain both worker and controlplane roles", i+1)
-		}
 	}
 	return nil
 }