Add a method to extract restConfig for certain contextName in kubeconfig

pkg/kubernetes/config.go

@@ -0,0 +1,34 @@
+package kubernetes
+
+import (
+	"fmt"
+
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+func LoadClientConfig(cfgFile, contextName string) (*rest.Config, error) {
+	config, err := clientcmd.LoadFromFile(cfgFile)
+	if err != nil {
+		return nil, err
+	}
+
+	if contextName != "" {
+		if _, found := config.Contexts[contextName]; !found {
+			return nil, fmt.Errorf("context %s not found in kubeconfig file", contextName)
+		}
+	}
+	config.CurrentContext = contextName
+
+	b, err := clientcmd.Write(*config)
+	if err != nil {
+		return nil, err
+	}
+
+	clientConfig, err := clientcmd.NewClientConfigFromBytes(b)
+	if err != nil {
+		return nil, err
+	}
+
+	return clientConfig.ClientConfig()
+}

pkg/kubernetes/config_test.go

@@ -0,0 +1,61 @@
+package kubernetes
+
+import (
+	"math/rand"
+	"os/user"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+func TestLoadConfigurationContext(t *testing.T) {
+	require := require.New(t)
+
+	conf, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
+	require.NoError(err)
+
+	if _, found := conf.Contexts["kind-kind"]; !found {
+		t.Skip("kind-kind context not found in kubeconfig")
+	}
+
+	restConfig, err := LoadClientConfig(defaultConfigPath(t), "kind-kind")
+	require.NoError(err)
+
+	// mTLS auth has KeyData & CertData
+	require.NotNil(restConfig.KeyData)
+	require.NotNil(restConfig.CertData)
+	require.NotNil(restConfig.CAData)
+	require.True(strings.HasPrefix(restConfig.Host, "https://127.0.0.1"))
+}
+
+func TestVerifyContextWasChanged(t *testing.T) {
+	require := require.New(t)
+
+	conf, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
+	require.NoError(err)
+
+	if len(conf.Contexts) < 1 {
+		t.Skip("no context found in kubeconfig")
+	}
+
+	keys := reflect.ValueOf(conf.Contexts).MapKeys()
+	randomContextName := keys[rand.Intn(len(keys))].String()
+
+	randomContext := conf.Contexts[randomContextName]
+	randomServer := conf.Clusters[randomContext.Cluster].Server
+
+	restConfig, err := LoadClientConfig(defaultConfigPath(t), randomContextName)
+	require.NoError(err)
+	require.NotNil(restConfig.CAData)
+	require.Equal(randomServer, restConfig.Host)
+}
+
+func defaultConfigPath(t *testing.T) string {
+	u, err := user.Current()
+	require.NoError(t, err)
+	return filepath.Join(u.HomeDir, ".kube", "config")
+}