Fix KUBECONFIG default behaviour

So far, the `havener` CLI did not behave the same way as `kubectl`, when it
comes to the Kubernetes configuration usage. If the `KUBECONFIG` environment
variable is set, this should always take precedence over the command line flag
or the default system location for the Kubernetes configuration.

Unify usage of `havener.NewHavener` function call.

Introduce options to `NewHavener` function to be able to override settings.

Add check for `KUBECONFIG` environment variable.

internal/cmd/events.go

@@ -26,7 +26,6 @@ import (
 	"time"
 
 	"github.com/spf13/cobra"
-	"github.com/spf13/viper"
 
 	"github.com/gonvenience/bunt"
 	"github.com/gonvenience/wrap"
@@ -56,15 +55,12 @@ var eventsCmd = &cobra.Command{
 	SilenceUsage:  true,
 	SilenceErrors: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		kubeConfig := viper.GetString("kubeconfig")
-		switch {
-		case len(kubeConfig) > 0:
-			return retrieveClusterEvents(kubeConfig)
-
-		default:
-			cmd.Usage()
+		hvnr, err := havener.NewHavener(havener.KubeConfig(kubeConfig))
+		if err != nil {
+			return wrap.Error(err, "unable to get access to cluster")
 		}
-		return nil
+
+		return retrieveClusterEvents(hvnr)
 	},
 }
 
@@ -74,13 +70,8 @@ func init() {
 	eventsCmd.PersistentFlags().StringVarP(&namespaceFilter, "namespace", "n", "", "Filter events for specific namespace")
 }
 
-func retrieveClusterEvents(kubeConfig string) error {
-	client, _, err := havener.OutOfClusterAuthentication(kubeConfig)
-	if err != nil {
-		return wrap.Error(err, "failed to access cluster")
-	}
-
-	namespaces, err := havener.ListNamespaces(client)
+func retrieveClusterEvents(hvnr havener.Havener) error {
+	namespaces, err := havener.ListNamespaces(hvnr.Client())
 	if err != nil {
 		return wrap.Error(err, "failed to get a list of namespaces")
 	}
@@ -96,7 +87,7 @@ func retrieveClusterEvents(kubeConfig string) error {
 		}
 
 		go func() error {
-			watcher, err := client.CoreV1().Events(namespace).Watch(context.TODO(), metav1.ListOptions{})
+			watcher, err := hvnr.Client().CoreV1().Events(namespace).Watch(context.TODO(), metav1.ListOptions{})
 			if err != nil {
 				return wrap.Error(err, "failed to setup event watcher")
 			}

internal/cmd/logs.go

@@ -54,7 +54,12 @@ The download includes all deployment YAMLs of the pods and the describe output.`
 	SilenceUsage:  true,
 	SilenceErrors: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		return retrieveClusterLogs()
+		hvnr, err := havener.NewHavener(havener.KubeConfig(kubeConfig))
+		if err != nil {
+			return wrap.Error(err, "unable to get access to cluster")
+		}
+
+		return retrieveClusterLogs(hvnr)
 	},
 }
 
@@ -67,12 +72,7 @@ func init() {
 	logsCmd.PersistentFlags().IntVar(&parallelDownloads, "parallel", 64, "number of parallel download jobs")
 }
 
-func retrieveClusterLogs() error {
-	hvnr, err := havener.NewHavener()
-	if err != nil {
-		return wrap.Error(err, "unable to get access to cluster")
-	}
-
+func retrieveClusterLogs(hvnr havener.Havener) error {
 	var commonText string
 	if excludeConfigFiles {
 		commonText = "log files"

internal/cmd/nexec.go

@@ -81,7 +81,12 @@ all nodes automatically.
 	SilenceUsage:  true,
 	SilenceErrors: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		return execInClusterNodes(args)
+		hvnr, err := havener.NewHavener(havener.KubeConfig(kubeConfig))
+		if err != nil {
+			return wrap.Error(err, "unable to get access to cluster")
+		}
+
+		return execInClusterNodes(hvnr, args)
 	},
 }
 
@@ -95,16 +100,12 @@ func init() {
 	nodeExecCmd.PersistentFlags().IntVar(&nodeExecMaxParallel, "max-parallel", 0, "number of parallel executions (defaults to number of nodes)")
 }
 
-func execInClusterNodes(args []string) error {
-	hvnr, err := havener.NewHavener()
-	if err != nil {
-		return wrap.Error(err, "unable to get access to cluster")
-	}
-
+func execInClusterNodes(hvnr havener.Havener, args []string) error {
 	var (
 		nodes   []corev1.Node
 		input   string
 		command []string
+		err     error
 	)
 
 	switch {

internal/cmd/pexec.go

@@ -76,7 +76,12 @@ all pods in all namespaces automatically.
 	SilenceUsage:  true,
 	SilenceErrors: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		return execInClusterPods(args)
+		hvnr, err := havener.NewHavener(havener.KubeConfig(kubeConfig))
+		if err != nil {
+			return wrap.Error(err, "unable to get access to cluster")
+		}
+
+		return execInClusterPods(hvnr, args)
 	},
 }
 
@@ -87,17 +92,13 @@ func init() {
 	podExecCmd.PersistentFlags().BoolVar(&podExecBlock, "block", false, "show distributed shell output as block for each pod")
 }
 
-func execInClusterPods(args []string) error {
-	hvnr, err := havener.NewHavener()
-	if err != nil {
-		return wrap.Error(err, "unable to get access to cluster")
-	}
-
+func execInClusterPods(hvnr havener.Havener, args []string) error {
 	var (
 		podMap          map[*corev1.Pod][]string
 		countContainers int
 		input           string
 		command         []string
+		err             error
 	)
 
 	switch {

internal/cmd/root.go

@@ -25,10 +25,10 @@ import (
 	"fmt"
 	"net/url"
 	"os"
-	"path/filepath"
 	"runtime/debug"
 	"strings"
 
+	"github.com/homeport/havener/pkg/havener"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 
@@ -38,6 +38,8 @@ import (
 	"github.com/gonvenience/wrap"
 )
 
+var kubeConfig string
+
 // rootCmd represents the base command when called without any subcommands
 var rootCmd = &cobra.Command{
 	Use:   "havener",
@@ -96,15 +98,16 @@ func Execute() {
 }
 
 func init() {
-	home, err := os.UserHomeDir()
+	kubeConfigDefault, err := havener.KubeConfigDefault()
 	if err != nil {
-		panic(wrap.Error(err, "unable to get home directory"))
+		panic(err)
 	}
 
 	rootCmd.Flags().SortFlags = false
 	rootCmd.PersistentFlags().SortFlags = false
 
-	rootCmd.PersistentFlags().String("kubeconfig", filepath.Join(home, ".kube", "config"), "Kubernetes configuration file")
+	rootCmd.PersistentFlags().StringVar(&kubeConfig, "kubeconfig", kubeConfigDefault, "Kubernetes configuration file")
+
 	rootCmd.PersistentFlags().Int("terminal-width", -1, "disable autodetection and specify an explicit terminal width")
 	rootCmd.PersistentFlags().Int("terminal-height", -1, "disable autodetection and specify an explicit terminal height")
 
@@ -116,7 +119,6 @@ func init() {
 	rootCmd.PersistentFlags().Bool("trace", false, "trace output - level 6")
 
 	// Bind environment variables to CLI flags
-	viper.BindPFlag("kubeconfig", rootCmd.PersistentFlags().Lookup("kubeconfig"))
 	viper.BindPFlag("TERMINAL_WIDTH", rootCmd.PersistentFlags().Lookup("terminal-width"))
 	viper.BindPFlag("TERMINAL_HEIGHT", rootCmd.PersistentFlags().Lookup("terminal-height"))
 

internal/cmd/top.go

@@ -70,7 +70,7 @@ cluster as well as a list per node.
 			topCmdSettings.cycles = 1
 		}
 
-		hvnr, err := havener.NewHavener()
+		hvnr, err := havener.NewHavener(havener.KubeConfig(kubeConfig))
 		if err != nil {
 			return err
 		}

internal/cmd/watch.go

@@ -48,7 +48,7 @@ var watchCmd = &cobra.Command{
 	Short: "Watch status of all pods in all namespaces",
 	Long:  `Continuesly creates a list of all pods in all namespaces.`,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		hvnr, err := havener.NewHavener()
+		hvnr, err := havener.NewHavener(havener.KubeConfig(kubeConfig))
 		if err != nil {
 			return err
 		}

pkg/havener/common.go

@@ -21,44 +21,42 @@
 package havener
 
 import (
-	"flag"
 	"fmt"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"strings"
 
 	_ "k8s.io/client-go/plugin/pkg/client/auth/oidc" //from https://github.com/kubernetes/client-go/issues/345
 
-	"github.com/spf13/viper"
+	"github.com/gonvenience/wrap"
 	"gopkg.in/yaml.v3"
-	"k8s.io/apimachinery/pkg/apis/meta/v1"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
 )
 
-var kubeconfig *string
-
-func getKubeConfig() string {
-	if kubeconfig == nil {
-		if home := HomeDir(); home != "" {
-			kubeconfig = flag.String("kubeconfig", viper.GetString("kubeconfig"), "(optional) absolute path to the kubeconfig file")
-		}
-		flag.Parse()
+// KubeConfigDefault returns assumed default locaation of the Kubernetes
+// configuration, which is expected to be `$HOME/.kube/config`.
+func KubeConfigDefault() (string, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", wrap.Error(err, "unable to get home directory")
 	}
 
-	return *kubeconfig
+	return filepath.Join(home, ".kube", "config"), nil
 }
 
-//OutOfClusterAuthentication for kube authentication from the outside
-func OutOfClusterAuthentication(kubeConfig string) (*kubernetes.Clientset, *rest.Config, error) {
-	logf(Verbose, "Connecting to Kubernetes cluster...")
-
+// outOfClusterAuthentication for kube authentication from the outside
+func outOfClusterAuthentication(kubeConfig string) (*kubernetes.Clientset, *rest.Config, error) {
 	if kubeConfig == "" {
-		kubeConfig = getKubeConfig()
+		return nil, nil, fmt.Errorf("no kube config supplied")
 	}
 
+	logf(Verbose, "Connecting to Kubernetes cluster...")
+
 	// BuildConfigFromFlags is a helper function that builds configs from a master
 	// url or a kubeconfig filepath.
 	config, err := clientcmd.BuildConfigFromFlags("", kubeConfig)
@@ -73,14 +71,6 @@ func OutOfClusterAuthentication(kubeConfig string) (*kubernetes.Clientset, *rest
 	return clientset, config, err
 }
 
-// HomeDir returns the HOME env key
-func HomeDir() string {
-	if h := os.Getenv("HOME"); h != "" {
-		return h
-	}
-	return os.Getenv("USERPROFILE") // windows
-}
-
 func isSystemNamespace(namespace string) bool {
 	switch namespace {
 	case "default", "kube-system", "ibm-system":

pkg/havener/havener.go

@@ -32,6 +32,7 @@ package havener
 import (
 	"fmt"
 	"io"
+	"os"
 	"time"
 
 	"github.com/gonvenience/wrap"
@@ -98,6 +99,16 @@ type Havener interface {
 	NodeExec(node corev1.Node, containerImage string, timeoutSeconds int, command []string, stdin io.Reader, stdout io.Writer, stderr io.Writer, tty bool) error
 }
 
+// Option provides a way to set specific settings for creating the Havener setup
+type Option func(*Hvnr)
+
+// KubeConfig is an option to set a specific Kubernetes configuration path
+func KubeConfig(kubeConfig string) Option {
+	return func(h *Hvnr) {
+		h.kubeConfigPath = kubeConfig
+	}
+}
+
 // NewHavenerFromFields returns a new Havener handle using the provided
 // input arguments (use for unit testing only)
 func NewHavenerFromFields(client kubernetes.Interface, restconfig *rest.Config, clusterName string, kubeConfigPath string) *Hvnr {
@@ -110,35 +121,37 @@ func NewHavenerFromFields(client kubernetes.Interface, restconfig *rest.Config,
 }
 
 // NewHavener returns a new Havener handle to perform cluster actions
-func NewHavener(kubeConfigs ...string) (*Hvnr, error) {
-	var kubeConfigPath string
-	switch len(kubeConfigs) {
-	case 0:
-		kubeConfigPath = getKubeConfig()
+func NewHavener(opts ...Option) (hvnr *Hvnr, err error) {
+	hvnr = &Hvnr{}
+	for _, opt := range opts {
+		opt(hvnr)
+	}
 
-	case 1:
-		kubeConfigPath = kubeConfigs[0]
+	// In case `KUBECONFIG` environment variable is set, this will take
+	// precedence over command line flag or default value
+	if value, ok := os.LookupEnv("KUBECONFIG"); ok {
+		hvnr.kubeConfigPath = value
+	}
 
-	default:
-		return nil, fmt.Errorf("multiple Kubernetes configurations are currently not supported")
+	// In case there is no Kubernetes configuration set, use the default
+	if hvnr.kubeConfigPath == "" {
+		hvnr.kubeConfigPath, err = KubeConfigDefault()
+		if err != nil {
+			return nil, wrap.Error(err, "failed to look-up default kube config")
+		}
 	}
 
-	client, restconfig, err := OutOfClusterAuthentication(kubeConfigPath)
+	hvnr.client, hvnr.restconfig, err = outOfClusterAuthentication(hvnr.kubeConfigPath)
 	if err != nil {
 		return nil, wrap.Error(err, "unable to get access to cluster")
 	}
 
-	clusterName, err := clusterName(kubeConfigPath)
+	hvnr.clusterName, err = clusterName(hvnr.kubeConfigPath)
 	if err != nil {
 		return nil, wrap.Error(err, "unable to get cluster name")
 	}
 
-	return &Hvnr{
-		client:         client,
-		restconfig:     restconfig,
-		clusterName:    clusterName,
-		kubeConfigPath: kubeConfigPath,
-	}, nil
+	return hvnr, nil
 }
 
 // ClusterName returns the name of the currently configured cluster