Remove panics and make all errors flow to the top

cmd/root.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -15,7 +16,7 @@ var settings environment.AirshipADMSettings
 
 // NewRootCmd creates the root `airshipadm` command. All other commands are
 // subcommands branching from this one
-func NewRootCmd(out io.Writer, client *kube.Client, args []string) *cobra.Command {
+func NewRootCmd(out io.Writer, client *kube.Client, args []string) (*cobra.Command, error) {
 	rootCmd := &cobra.Command{
 		Use:   "airshipadm",
 		Short: "airshipadm is a unified entrypoint to various airship components",
@@ -25,9 +26,8 @@ func NewRootCmd(out io.Writer, client *kube.Client, args []string) *cobra.Comman
 	// Settings flags - This section should probably be moved to pkg/environment
 	rootCmd.PersistentFlags().StringVar(&settings.KubeConfigFilePath, "kubeconfig", "", "path to kubeconfig")
 	rootCmd.PersistentFlags().BoolVar(&settings.Debug, "debug", false, "enable verbose output")
-	// TODO(howell): Remove this panic
 	if err := rootCmd.PersistentFlags().Parse(args); err != nil {
-		panic(err.Error())
+		return nil, errors.New("could not parse flags: " + err.Error())
 	}
 
 	log.Init(&settings, out)
@@ -36,21 +36,21 @@ func NewRootCmd(out io.Writer, client *kube.Client, args []string) *cobra.Comman
 
 	// Compound commands
 	rootCmd.AddCommand(NewWorkflowCommand())
-
-	return rootCmd
+	return rootCmd, nil
 }
 
 // Execute runs the base airshipadm command
 func Execute(out io.Writer) {
-	// TODO(howell): Remove this panic
 	client, err := kube.NewForConfig(settings.KubeConfigFilePath)
-	if err != nil {
-		panic(err.Error())
-	}
+	osExitIfError(out, err)
+	rootCmd, err := NewRootCmd(out, client, os.Args[1:])
+	osExitIfError(out, err)
+	osExitIfError(out, rootCmd.Execute())
+}
 
-	rootCmd := NewRootCmd(out, client, os.Args[1:])
-	if err := rootCmd.Execute(); err != nil {
-		fmt.Println(err)
+func osExitIfError(out io.Writer, err error) {
+	if err != nil {
+		fmt.Fprintln(out, err)
 		os.Exit(1)
 	}
 }

cmd/version.go

@@ -23,10 +23,17 @@ func NewVersionCommand(out io.Writer, client *kube.Client) *cobra.Command {
 		Short: "Show the version number of airshipadm and its underlying tools",
 		Long:  versionLong,
 		Run: func(cmd *cobra.Command, args []string) {
+			clientV := clientVersion()
+			kubeV, err := kubeVersion(client)
+			if err != nil {
+				fmt.Fprintf(out, "Could not get kubernetes version")
+				return
+			}
+
 			w := tabwriter.NewWriter(out, 0, 0, 1, ' ', 0)
-			fmt.Fprintf(w, "%s:\t%s\n", "client", clientVersion())
-			fmt.Fprintf(w, "%s:\t%s\n", "kubernetes server", kubeVersion(client))
-			w.Flush()
+			defer w.Flush()
+			fmt.Fprintf(w, "%s:\t%s\n", "client", clientV)
+			fmt.Fprintf(w, "%s:\t%s\n", "kubernetes server", kubeV)
 		},
 	}
 	return versionCmd
@@ -37,11 +44,10 @@ func clientVersion() string {
 	return "v0.1.0"
 }
 
-func kubeVersion(client *kube.Client) string {
+func kubeVersion(client *kube.Client) (string, error) {
 	version, err := client.Discovery().ServerVersion()
-	// TODO(howell): Remove this panic
 	if err != nil {
-		panic(err.Error())
+		return "", err
 	}
-	return version.String()
+	return version.String(), nil
 }

internal/test/utilities.go

@@ -30,7 +30,6 @@ type CmdTest struct {
 
 func RunCmdTests(t *testing.T, tests []CmdTest) {
 	t.Helper()
-
 	for _, test := range tests {
 		cmdOutput := executeCmd(t, test.Command)
 		if *shouldUpdateGolden {
@@ -46,7 +45,11 @@ func executeCmd(t *testing.T, command string) []byte {
 	client := &kube.Client{Interface: fake.NewSimpleClientset()}
 	// TODO(howell): switch to shellwords (or similar)
 	args := strings.Fields(command)
-	rootCmd := cmd.NewRootCmd(&actual, client, args)
+	rootCmd, err := cmd.NewRootCmd(&actual, client, args)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
 	rootCmd.SetArgs(args)
 
 	if err := rootCmd.Execute(); err != nil {

pkg/kube/clientset.go

@@ -1,6 +1,7 @@
 package kube
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 
@@ -18,7 +19,7 @@ func NewForConfig(kubeconfigFilepath string) (*Client, error) {
 	if kubeconfigFilepath == "" {
 		home, err := os.UserHomeDir()
 		if err != nil {
-			panic(err.Error())
+			return nil, errors.New("could not find kubernetes config file: " + err.Error())
 		}
 		kubeconfigFilepath = filepath.Join(home, ".kube", "config")
 	}
@@ -26,13 +27,13 @@ func NewForConfig(kubeconfigFilepath string) (*Client, error) {
 	// use the current context in kubeconfigFilepath
 	config, err := clientcmd.BuildConfigFromFlags("", kubeconfigFilepath)
 	if err != nil {
-		panic(err.Error())
+		return nil, err
 	}
 
 	// create the clientset
 	clientset, err := kubernetes.NewForConfig(config)
 	if err != nil {
-		panic(err.Error())
+		return nil, err
 	}
 	return &Client{clientset}, nil
 }