Merge pull request #150 from dlorenc/retry

Add a retry utility to util, and use it to retry cluster creation.

cmd/minikube/cmd/start.go

@@ -22,12 +22,14 @@ import (
 	"strings"
 
 	"github.com/docker/machine/libmachine"
+	"github.com/docker/machine/libmachine/host"
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
 	cfg "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
 	"k8s.io/minikube/pkg/minikube/cluster"
 	"k8s.io/minikube/pkg/minikube/constants"
 	"k8s.io/minikube/pkg/minikube/kubeconfig"
+	"k8s.io/minikube/pkg/util"
 )
 
 var (
@@ -52,8 +54,12 @@ func runStart(cmd *cobra.Command, args []string) {
 		MinikubeISO: minikubeISO,
 	}
 
-	host, err := cluster.StartHost(api, config)
-
+	var host *host.Host
+	start := func() (err error) {
+		host, err = cluster.StartHost(api, config)
+		return err
+	}
+	err := util.Retry(3, start)
 	if err != nil {
 		glog.Errorln("Error starting host: ", err)
 		os.Exit(1)

pkg/util/utils.go

@@ -61,3 +61,13 @@ func CanReadFile(path string) bool {
 
 	return true
 }
+
+func Retry(attempts int, callback func() error) (err error) {
+	for i := 0; i < attempts; i++ {
+		err = callback()
+		if err == nil {
+			return nil
+		}
+	}
+	return err
+}

pkg/util/utils_test.go

@@ -0,0 +1,61 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"fmt"
+	"testing"
+)
+
+// Returns a function that will return n errors, then return successfully forever.
+func errorGenerator(n int) func() error {
+	errors := 0
+	return func() (err error) {
+		if errors < n {
+			errors += 1
+			return fmt.Errorf("Error!")
+		}
+		return nil
+	}
+}
+
+func TestErrorGenerator(t *testing.T) {
+	errors := 3
+	f := errorGenerator(errors)
+	for i := 0; i < errors-1; i++ {
+		if err := f(); err == nil {
+			t.Fatalf("Error should have been thrown at iteration %v", i)
+		}
+	}
+	if err := f(); err == nil {
+		t.Fatalf("Error should not have been thrown this call!")
+	}
+}
+
+func TestRetry(t *testing.T) {
+
+	f := errorGenerator(4)
+	if err := Retry(5, f); err != nil {
+		t.Fatalf("Error should not have been raised by retry.")
+	}
+
+	f = errorGenerator(5)
+	if err := Retry(4, f); err == nil {
+		t.Fatalf("Error should have been raised by retry.")
+	}
+
+}