refact(csi): use common lib-csi imports (#263)

Signed-off-by: shubham <shubham.bajpai@mayadata.io>

vendor/github.com/openebs/lib-csi/pkg/common/kubernetes/client/client.go

@@ -0,0 +1,250 @@
+/*
+Copyright 2019 The OpenEBS Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package client
+
+import (
+	"strings"
+	"sync"
+
+	env "github.com/openebs/lib-csi/pkg/common/env"
+	"github.com/pkg/errors"
+	"k8s.io/client-go/dynamic"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+// getInClusterConfigFunc abstracts the logic to get
+// kubernetes incluster config
+//
+// NOTE:
+//  typed function makes it simple to mock
+type getInClusterConfigFunc func() (*rest.Config, error)
+
+// buildConfigFromFlagsFunc provides the abstraction to get
+// kubernetes config from provided flags
+//
+// NOTE:
+//  typed function makes it simple to mock
+type buildConfigFromFlagsFunc func(string, string) (*rest.Config, error)
+
+// GetConfigFunc provides the abstraction to get
+// kubernetes config from provided client instance
+//
+// NOTE:
+//  typed function makes it simple to mock
+type GetConfigFunc func(*Client) (*rest.Config, error)
+
+// GetConfig returns kubernetes config instance
+//
+// NOTE:
+//  This is an implementation of GetConfigFunc
+func GetConfig(c *Client) (*rest.Config, error) {
+	if c == nil {
+		return nil, errors.New("failed to get kubernetes config: nil client was provided")
+	}
+	return c.GetConfigForPathOrDirect()
+}
+
+// getKubeMasterIPFunc provides the abstraction to get
+// kubernetes master IP address
+//
+// NOTE:
+//  typed function makes it simple to mock
+type getKubeMasterIPFunc func(string) string
+
+// getKubeConfigPathFunc provides the abstraction to get
+// kubernetes config path
+//
+// NOTE:
+//  typed function makes it simple to mock
+type getKubeConfigPathFunc func(string) string
+
+// getKubernetesDynamicClientFunc provides the abstraction to get
+// dynamic kubernetes clientset
+//
+// NOTE:
+//  typed function makes it simple to mock
+type getKubernetesDynamicClientFunc func(*rest.Config) (dynamic.Interface, error)
+
+// getKubernetesClientsetFunc provides the abstraction to get
+// kubernetes clientset
+//
+// NOTE:
+//  typed function makes it simple to mock
+type getKubernetesClientsetFunc func(*rest.Config) (*kubernetes.Clientset, error)
+
+// Client provides common kuberenetes client operations
+type Client struct {
+	IsInCluster    bool   // flag to let client point to its own cluster
+	KubeConfigPath string // kubeconfig path to get kubernetes clientset
+
+	// Below functions are useful during mock
+
+	// handle to get in cluster config
+	getInClusterConfig getInClusterConfigFunc
+
+	// handle to get desired kubernetes config
+	buildConfigFromFlags buildConfigFromFlagsFunc
+
+	// handle to get kubernetes clienset
+	getKubernetesClientset getKubernetesClientsetFunc
+
+	// handle to get dynamic kubernetes clientset
+	getKubernetesDynamicClient getKubernetesDynamicClientFunc
+
+	// handle to get kubernetes master IP
+	getKubeMasterIP getKubeMasterIPFunc
+
+	// handle to get kubernetes config path
+	getKubeConfigPath getKubeConfigPathFunc
+}
+
+// OptionFunc is a typed function that abstracts any kind of operation
+// against the provided client instance
+//
+// This is the basic building block to create functional operations
+// against the client instance
+type OptionFunc func(*Client)
+
+// New returns a new instance of client
+func New(opts ...OptionFunc) *Client {
+	c := &Client{}
+	for _, o := range opts {
+		o(c)
+	}
+	withDefaults(c)
+	return c
+}
+
+var (
+	instance *Client
+	once     sync.Once
+)
+
+// Instance returns a singleton instance of
+// this client
+func Instance(opts ...OptionFunc) *Client {
+	once.Do(func() {
+		instance = New(opts...)
+	})
+
+	return instance
+}
+
+func withDefaults(c *Client) {
+	if c.getInClusterConfig == nil {
+		c.getInClusterConfig = rest.InClusterConfig
+	}
+	if c.buildConfigFromFlags == nil {
+		c.buildConfigFromFlags = clientcmd.BuildConfigFromFlags
+	}
+	if c.getKubernetesClientset == nil {
+		c.getKubernetesClientset = kubernetes.NewForConfig
+	}
+	if c.getKubernetesDynamicClient == nil {
+		c.getKubernetesDynamicClient = dynamic.NewForConfig
+	}
+	if c.getKubeMasterIP == nil {
+		c.getKubeMasterIP = env.Get
+	}
+	if c.getKubeConfigPath == nil {
+		c.getKubeConfigPath = env.Get
+	}
+}
+
+// InCluster enables IsInCluster flag
+func InCluster() OptionFunc {
+	return func(c *Client) {
+		c.IsInCluster = true
+	}
+}
+
+// WithKubeConfigPath sets kubeconfig path
+// against this client instance
+func WithKubeConfigPath(kubeConfigPath string) OptionFunc {
+	return func(c *Client) {
+		c.KubeConfigPath = kubeConfigPath
+	}
+}
+
+// Clientset returns a new instance of kubernetes clientset
+func (c *Client) Clientset() (*kubernetes.Clientset, error) {
+	config, err := c.GetConfigForPathOrDirect()
+	if err != nil {
+		return nil, errors.Wrapf(err,
+			"failed to get kubernetes clientset: failed to get kubernetes config: IsInCluster {%t}: KubeConfigPath {%s}",
+			c.IsInCluster,
+			c.KubeConfigPath,
+		)
+	}
+	return c.getKubernetesClientset(config)
+}
+
+// Config returns the kubernetes config instance based on available criteria
+func (c *Client) Config() (config *rest.Config, err error) {
+	// IsInCluster flag holds the top most priority
+	if c.IsInCluster {
+		return c.getInClusterConfig()
+	}
+
+	// ENV holds second priority
+	if strings.TrimSpace(c.getKubeMasterIP(env.KubeMaster)) != "" ||
+		strings.TrimSpace(c.getKubeConfigPath(env.KubeConfig)) != "" {
+		return c.getConfigFromENV()
+	}
+
+	// Defaults to InClusterConfig
+	return c.getInClusterConfig()
+}
+
+// ConfigForPath returns the kubernetes config instance based on KubeConfig path
+func (c *Client) ConfigForPath(kubeConfigPath string) (config *rest.Config, err error) {
+	return c.buildConfigFromFlags("", kubeConfigPath)
+}
+
+// GetConfigForPathOrDirect returns the kubernetes config instance based on direct KubeConfig
+func (c *Client) GetConfigForPathOrDirect() (config *rest.Config, err error) {
+	if c.KubeConfigPath != "" {
+		return c.ConfigForPath(c.KubeConfigPath)
+	}
+	return c.Config()
+}
+
+func (c *Client) getConfigFromENV() (config *rest.Config, err error) {
+	k8sMaster := c.getKubeMasterIP(env.KubeMaster)
+	kubeConfig := c.getKubeConfigPath(env.KubeConfig)
+	if strings.TrimSpace(k8sMaster) == "" &&
+		strings.TrimSpace(kubeConfig) == "" {
+		return nil, errors.Errorf(
+			"failed to get kubernetes config: missing ENV: atleast one should be set: {%s} or {%s}",
+			env.KubeMaster,
+			env.KubeConfig,
+		)
+	}
+	return c.buildConfigFromFlags(k8sMaster, kubeConfig)
+}
+
+// Dynamic returns a kubernetes dynamic client capable of invoking operations
+// against kubernetes resources
+func (c *Client) Dynamic() (dynamic.Interface, error) {
+	config, err := c.GetConfigForPathOrDirect()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get dynamic client")
+	}
+	return c.getKubernetesDynamicClient(config)
+}