--apiserver-names does not work as expected when you run minikube start a second time

[jemygraw]

Related issue: #8658

Steps to reproduce the issue:

1. minikube start --apiserver-names=k8s-beta.example.com --apiserver-names=k8s-prod-replica.example.com

Version:

appdelivery@appdelivery-qvm-1:~$ minikube version
minikube version: v1.12.1
commit: 997fd89b9d3a0072e3112c79d906b6367e760473-dirty

Details: it is right when you first run the minikube start command, and when you re-run the minikube start with the same flags, it is wrong. So if you just run a new minikube, you will not reproduce it. I found the code which cause this error:

First Run
https://github.com/kubernetes/minikube/blob/master/cmd/minikube/cmd/start_flags.go#L162

startCmd.Flags().StringArrayVar(&apiServerNames, "apiserver-names", nil, "A set of apiserver names which are used in the generated certificate for kubernetes.  This can be used if you want to make the apiserver available from outside the machine")

Second Run
https://github.com/kubernetes/minikube/blob/master/cmd/minikube/cmd/start_flags.go#L539

cc.KubernetesConfig.APIServerNames = viper.GetStringSlice("apiserver-names")

Because the apiserverNames is first get by StringArrayVar which support the above format of --apiserver-names=k8s-beta.example.com --apiserver-names=k8s-prod-replica.example.com to specify multiple values for a single flag, but when you re-run minikue, it will use viper.GetStringSlice to get the values from the command line flags.viper.GetStringSlice supports the format of --apiserver-names=k8s-beta.example.com,k8s-prod-replica.example.com.

So when you output the values of the above code, it will output:

I0813 14:45:12.401533   90740 start_flags.go:539] existing: {v1.18.3 minikube minikubeCA [k8s-beta.duokexuetang.com k8s-prod-replica.duokexuetang.com] [] cluster.local docker    10.96.0.0/12    [] true false   8443 }
I0813 14:45:12.401574   90740 start_flags.go:540] viper: [[k8s-beta.duokexuetang.com,k8s-prod-replica.duokexuetang.com]]

---

I write a simple program to express what happens.

package main

import (
	"encoding/json"
	"fmt"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

var apiserverNames []string

type ClusterConfig struct {
	KubernetesConfig KubernetesConfig
}

type KubernetesConfig struct {
	APIServerNames []string
}

var startCmd = cobra.Command{
	Use: "start",
	Run: func(cmd *cobra.Command, args []string) {
		fmt.Println("apiserverNames=", viper.GetStringSlice("apiserver-names"))
		kubeConfig := KubernetesConfig{
			APIServerNames: apiserverNames,
		}
		clusterConfig := ClusterConfig{
			KubernetesConfig: kubeConfig,
		}
		data, _ := json.MarshalIndent(&clusterConfig, "", "    ")
		fmt.Println("Output=", string(data))
	},
}

func init() {
	startCmd.PersistentFlags().StringArrayVar(&apiserverNames, "apiserver-names", nil, "apiserver names")
	viper.BindPFlags(startCmd.PersistentFlags())
}

func main() {
	rootCmd := cobra.Command{}
	rootCmd.AddCommand(&startCmd)
	fmt.Println(rootCmd.Execute())
}

Output:

apiserverNames= [[hello,world]]
Output= {
    "KubernetesConfig": {
        "APIServerNames": [
            "hello",
            "world"
        ]
    }
}

[priyawadhwa]

Hey @jemygraw thanks for opening an issue for this bug. If you, or anyone else, would be interested in fixing this bug, feel free to assign yourself to this issue by commenting /assign.

[gm7y8]

/assign