Wait for tailscale client to be ready after tailscale up

integration/scenario.go

@@ -258,7 +258,13 @@ func (s *Scenario) RunTailscaleUp(
 				// TODO(kradalby): error handle this
 				_ = c.Up(loginServer, authKey)
 			}(client)
+
+			err := client.WaitForReady()
+			if err != nil {
+				log.Printf("error waiting for client %s to be ready: %s", client.Hostname(), err)
+			}
 		}
+
 		namespace.joinWaitGroup.Wait()
 
 		return nil