Add cache list support

cmd/minikube/cmd/cache_list.go

@@ -0,0 +1,73 @@
+/*
+Copyright 2017 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 cmd
+
+import (
+	"fmt"
+	"os"
+	"text/template"
+
+	"github.com/spf13/cobra"
+	cmdConfig "k8s.io/minikube/cmd/minikube/cmd/config"
+	"k8s.io/minikube/pkg/minikube/constants"
+)
+
+const cacheListFormat = "- {{.CacheImageName}}\n"
+
+type CacheListTemplate struct {
+	CacheImageName string
+}
+
+// listCacheCmd represents the cache list command
+var listCacheCmd = &cobra.Command{
+	Use:   "list",
+	Short: "List all available images from the local cache.",
+	Long:  "List all available images from the local cache.",
+	Run: func(cmd *cobra.Command, args []string) {
+		// list images from config file
+		images, err := cmdConfig.ListConfigMap(constants.Cache)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error listing image entries from config: %s\n", err)
+			os.Exit(1)
+		}
+		if err := cacheList(images); err != nil {
+			fmt.Fprintf(os.Stderr, "Error listing images: %s\n", err)
+			os.Exit(1)
+		}
+	},
+}
+
+func init() {
+	cacheCmd.AddCommand(listCacheCmd)
+}
+
+func cacheList(images map[string]interface{}) error {
+	for imageName := range images {
+		tmpl, err := template.New("list").Parse(cacheListFormat)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error creating list template: %s\n", err)
+			os.Exit(1)
+		}
+		listTmplt := CacheListTemplate{imageName}
+		err = tmpl.Execute(os.Stdout, listTmplt)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error executing list template: %s\n", err)
+			os.Exit(1)
+		}
+	}
+	return nil
+}

cmd/minikube/cmd/config/config.go

@@ -219,6 +219,21 @@ func configurableFields() string {
 	return strings.Join(fields, "\n")
 }
 
+// ListConfigMap list entries from config file
+func ListConfigMap(name string) (map[string]interface{}, error) {
+	configFile, err := config.ReadConfig()
+	if err != nil {
+		return nil, err
+	}
+	newImages := make(map[string]interface{})
+	if values, ok := configFile[name].(map[string]interface{}); ok {
+		for key := range values {
+			newImages[key] = nil
+		}
+	}
+	return newImages, nil
+}
+
 // AddToConfigMap adds entries to a map in the config file
 func AddToConfigMap(name string, images []string) error {
 	s, err := findSetting(name)

docs/cache.md

@@ -2,4 +2,15 @@
 
 Minikube supports caching non-minikube images using the `minikube cache` command. Images can be added to the cache by running `minikube cache add <img>`, and deleted by running `minikube cache delete <img>`.
 
-Images in the cache will be loaded on `minikube start`.
+Images in the cache will be loaded on `minikube start`. If you want to list all available cached images, you can use `minikube cache list` command to list. Below is an example of this functionality:
+
+```shell
+# cache a image into $HOME/.minikube/cache/images
+$ minikube cache add ubuntu:16.04
+$ minikube cache add redis:3
+
+# list cached images
+$ minikube cache list
+- redis:3
+- ubuntu:16.04
+```