Add logic to determine kubeconfig path

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

cmd/kubectx/kubeconfig.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+)
+
+func kubeconfigPath() (string, error) {
+	// KUBECONFIG env var
+	if v := os.Getenv("KUBECONFIG"); v != "" {
+		list := filepath.SplitList(v)
+		if len(list) > 1 {
+			// TODO KUBECONFIG=file1:file2 currently not supported
+			return "", errors.New("multiple files in KUBECONFIG currently not supported")
+		}
+		return v, nil
+	}
+
+	// return default path
+	home := os.Getenv("HOME")
+	if home == "" {
+		home = os.Getenv("USERPROFILE") // windows
+	}
+	if home == "" {
+		return "", errors.New("HOME or USERPROFILE environment variable not set")
+	}
+	return filepath.Join(home, ".kube", "config"), nil
+}

cmd/kubectx/kubeconfig_test.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func Test_kubeconfigPath_homePath(t *testing.T) {
+	origHome := os.Getenv("HOME")
+	os.Setenv("HOME", "/foo/bar")
+	defer os.Setenv("HOME", origHome)
+
+	got, err := kubeconfigPath()
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := filepath.Join(filepath.FromSlash("/foo/bar"), ".kube", "config")
+
+	if got != expected{
+		t.Fatalf("wrong value: expected=%s got=%s", expected, got)
+	}
+}
+
+func Test_kubeconfigPath_userprofile(t *testing.T) {
+	origHome := os.Getenv("HOME")
+	os.Unsetenv("HOME")
+	os.Setenv("USERPROFILE", "/foo/bar")
+	defer os.Setenv("HOME", origHome)
+
+	got, err := kubeconfigPath()
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := filepath.Join(filepath.FromSlash("/foo/bar"), ".kube", "config")
+
+	if got != expected{
+		t.Fatalf("wrong value: expected=%s got=%s", expected, got)
+	}
+}
+
+func Test_kubeconfigPath_noEnvVars(t *testing.T) {
+	origHome := os.Getenv("HOME")
+	origUserprofile := os.Getenv("USERPROFILE")
+	os.Unsetenv("HOME")
+	os.Unsetenv("USERPROFILE")
+	defer os.Setenv("HOME", origHome)
+	defer os.Setenv("USERPROFILE", origUserprofile)
+
+	_, err := kubeconfigPath()
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+}
+
+func Test_kubeconfigPath_envOvveride(t *testing.T) {
+	os.Setenv("KUBECONFIG", "foo")
+	defer os.Unsetenv("KUBECONFIG")
+
+	v, err := kubeconfigPath()
+	if err != nil { t.Fatal(err)}
+	if expected := "foo"; v != expected {
+		t.Fatalf("expected=%q, got=%q", expected, v)
+	}
+}
+
+func Test_kubeconfigPath_envOvverideDoesNotSupportPathSeparator(t *testing.T) {
+	path := strings.Join([]string{"file1","file2"}, string(os.PathListSeparator))
+	os.Setenv("KUBECONFIG", path)
+	defer os.Unsetenv("KUBECONFIG")
+
+	_, err := kubeconfigPath()
+	if err == nil { t.Fatal("expected error")}
+
+}

cmd/kubectx/list.go

@@ -0,0 +1 @@
+package main