kubeconfig pkg for loading/parsing

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

cmd/kubectx/kubeconfig.go

@@ -6,8 +6,34 @@ import (
 
 	"github.com/pkg/errors"
 	"gopkg.in/yaml.v3"
+
+	"github.com/ahmetb/kubectx/cmd/kubectx/kubeconfig"
 )
 
+type defaultKubeconfigLoader struct{}
+
+type kubeconfigFile struct { *os.File }
+
+func (kf *kubeconfigFile) Reset() error {
+	if err := kf.Truncate(0);err!= nil {
+		return errors.Wrap(err, "failed to truncate file")
+	}
+	_, err := kf.Seek(0,0)
+	return errors.Wrap(err, "failed to seek in file")
+}
+
+func (defaultKubeconfigLoader) Load() (kubeconfig.ReadWriteResetCloser, error) {
+	cfgPath, err := kubeconfigPath()
+	if err != nil {
+		return nil, errors.Wrap(err, "cannot determine kubeconfig path")
+	}
+	f, err := os.OpenFile(cfgPath, os.O_RDWR, 0)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to open file")
+	}
+	return &kubeconfigFile{f}, nil
+}
+
 func kubeconfigPath() (string, error) {
 	// KUBECONFIG env var
 	if v := os.Getenv("KUBECONFIG"); v != "" {
@@ -40,11 +66,10 @@ func homeDir() string {
 	return home
 }
 
-
 // TODO parseKubeconfig doesn't seem necessary when there's a raw version that returns what's needed
-func parseKubeconfig(path string) (kubeconfig, error) {
+func parseKubeconfig(path string) (kubeconfigContents, error) {
 	// TODO refactor to accept io.Reader instead of file
-	var v kubeconfig
+	var v kubeconfigContents
 
 	f, err := os.Open(path)
 	if err != nil {

cmd/kubectx/kubeconfig/kubeconfig.go

@@ -0,0 +1,55 @@
+package kubeconfig
+
+import (
+	"io"
+
+	"github.com/pkg/errors"
+	"gopkg.in/yaml.v3"
+)
+
+type ReadWriteResetCloser interface{
+	io.ReadWriteCloser
+
+	// Reset truncates the file and seeks to the beginning of the file.
+	Reset() error
+}
+
+type Loader interface {
+	Load() (ReadWriteResetCloser, error)
+}
+
+type Kubeconfig struct {
+	loader   Loader
+
+	f ReadWriteResetCloser
+	rootNode *yaml.Node
+}
+
+func (k *Kubeconfig) WithLoader(l Loader) {
+	k.loader = l
+}
+
+func (k *Kubeconfig) ParseRaw() (*yaml.Node, error) {
+	f, err := k.loader.Load()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to load kubeconfig")
+	}
+
+	k.f = f
+
+	var v yaml.Node
+	if err := yaml.NewDecoder(f).Decode(&v); err != nil {
+		return nil, errors.Wrap(err, "failed to decode kubeconfig")
+	}
+	k.rootNode = v.Content[0]
+	return k. rootNode, nil
+}
+
+func (k *Kubeconfig) Save() error {
+	if err := k.f.Reset(); err != nil {
+		return errors.Wrap(err, "failed to reset file")
+	}
+	enc := yaml.NewEncoder(k.f)
+	enc.SetIndent(2)
+	return enc.Encode(k.rootNode)
+}

cmd/kubectx/kubeconfig_raw.go

@@ -9,6 +9,7 @@ import (
 )
 
 func parseKubeconfigRaw(r io.Reader) (*yaml.Node, error) {
+	// TODO DELETE
 	var v yaml.Node
 	if err := yaml.NewDecoder(r).Decode(&v); err != nil {
 		return nil, err

cmd/kubectx/list.go

@@ -13,7 +13,7 @@ type context struct {
 	Name string `yaml:"name"`
 }
 
-type kubeconfig struct {
+type kubeconfigContents struct {
 	APIVersion     string    `yaml:"apiVersion"`
 	CurrentContext string    `yaml:"current-context"`
 	Contexts       []context `yaml:"contexts"`