Introduce new approach of config object loading

The new approach of config loading allows us to combine and move all
the config loading and verifications actions from cmd to pkg module;
it will be executed on demand only and save us from non expected
runtime errors. The examples of usage will be introduced in further
changes.

Change-Id: I1b4c29f9c5b1de3e46a1faf5c28fea5c7b3eb4e1
Signed-off-by: Ruslan Aliev <raliev@mirantis.com>

pkg/config/config.go

@@ -29,6 +29,7 @@ import (
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 	"sigs.k8s.io/yaml"
 
+	"opendev.org/airship/airshipctl/pkg/log"
 	"opendev.org/airship/airshipctl/pkg/util"
 )
 
@@ -87,6 +88,61 @@ type Permissions struct {
 	FilePermission      uint32
 }
 
+// Factory is a function which returns ready to use config object and error (if any)
+type Factory func() (*Config, error)
+
+// CreateFactory returns function which creates ready to use Config object
+func CreateFactory(airshipConfigPath *string, kubeConfigPath *string) Factory {
+	return func() (*Config, error) {
+		cfg := NewConfig()
+		cfg.kubeConfig = NewKubeConfig()
+
+		var acp, kcp string
+		if airshipConfigPath != nil {
+			acp = *airshipConfigPath
+		}
+		if kubeConfigPath != nil {
+			kcp = *kubeConfigPath
+		}
+
+		cfg.initConfigPath(acp, kcp)
+		err := cfg.LoadConfig(cfg.loadedConfigPath, cfg.kubeConfigPath, false)
+		if err != nil {
+			// Should stop airshipctl
+			log.Fatal("Failed to load or initialize config: ", err)
+		}
+
+		return cfg, cfg.EnsureComplete()
+	}
+}
+
+// initConfigPath - Initializes loadedConfigPath and kubeConfigPath variable for Config object
+func (c *Config) initConfigPath(airshipConfigPath string, kubeConfigPath string) {
+	switch {
+	case airshipConfigPath != "":
+		// The loadedConfigPath may already have been received as a command line argument
+		c.loadedConfigPath = airshipConfigPath
+	case os.Getenv(AirshipConfigEnv) != "":
+		// Otherwise, we can check if we got the path via ENVIRONMENT variable
+		c.loadedConfigPath = os.Getenv(AirshipConfigEnv)
+	default:
+		// Otherwise, we'll try putting it in the home directory
+		c.loadedConfigPath = filepath.Join(util.UserHomeDir(), AirshipConfigDir, AirshipConfig)
+	}
+
+	switch {
+	case kubeConfigPath != "":
+		// The kubeConfigPath may already have been received as a command line argument
+		c.kubeConfigPath = kubeConfigPath
+	case os.Getenv(AirshipKubeConfigEnv) != "":
+		// Otherwise, we can check if we got the path via ENVIRONMENT variable
+		c.kubeConfigPath = os.Getenv(AirshipKubeConfigEnv)
+	default:
+		// Otherwise, we'll try putting it in the home directory
+		c.kubeConfigPath = filepath.Join(util.UserHomeDir(), AirshipConfigDir, AirshipKubeConfig)
+	}
+}
+
 // LoadConfig populates the Config object using the files found at
 // airshipConfigPath and kubeConfigPath
 func (c *Config) LoadConfig(airshipConfigPath, kubeConfigPath string, create bool) error {
@@ -137,24 +193,7 @@ func (c *Config) loadKubeConfig(kubeConfigPath string, create bool) error {
 	var err error
 	if _, err = os.Stat(kubeConfigPath); os.IsNotExist(err) && create {
 		// Default kubeconfig matching Airship target cluster
-		c.kubeConfig = &clientcmdapi.Config{
-			Clusters: map[string]*clientcmdapi.Cluster{
-				AirshipDefaultContext: {
-					Server: "https://172.17.0.1:6443",
-				},
-			},
-			AuthInfos: map[string]*clientcmdapi.AuthInfo{
-				"admin": {
-					Username: "airship-admin",
-				},
-			},
-			Contexts: map[string]*clientcmdapi.Context{
-				AirshipDefaultContext: {
-					Cluster:  AirshipDefaultContext,
-					AuthInfo: "admin",
-				},
-			},
-		}
+		c.kubeConfig = NewKubeConfig()
 		return nil
 	} else if err != nil {
 		return err

pkg/config/utils.go

@@ -18,6 +18,8 @@ package config
 
 import (
 	"encoding/base64"
+
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 )
 
 // NewConfig returns a newly initialized Config object
@@ -58,6 +60,28 @@ func NewConfig() *Config {
 	}
 }
 
+// NewKubeConfig returns a newly initialized clientcmdapi.Config object, will be removed later
+func NewKubeConfig() *clientcmdapi.Config {
+	return &clientcmdapi.Config{
+		Clusters: map[string]*clientcmdapi.Cluster{
+			AirshipDefaultContext: {
+				Server: "https://172.17.0.1:6443",
+			},
+		},
+		AuthInfos: map[string]*clientcmdapi.AuthInfo{
+			"admin": {
+				Username: "airship-admin",
+			},
+		},
+		Contexts: map[string]*clientcmdapi.Context{
+			AirshipDefaultContext: {
+				Cluster:  AirshipDefaultContext,
+				AuthInfo: "admin",
+			},
+		},
+	}
+}
+
 // NewContext is a convenience function that returns a new Context
 func NewContext() *Context {
 	return &Context{}

pkg/environment/settings.go

@@ -59,6 +59,7 @@ func (a *AirshipCTLSettings) InitFlags(cmd *cobra.Command) {
 }
 
 // InitConfig - Initializes and loads Config if exists.
+// TODO (raliev) remove this function after completely switching to new approach of Config loading
 func (a *AirshipCTLSettings) InitConfig() {
 	a.Config = config.NewConfig()
 
@@ -73,6 +74,7 @@ func (a *AirshipCTLSettings) InitConfig() {
 }
 
 // InitAirshipConfigPath - Initializes AirshipConfigPath variable for Config object
+// TODO (raliev) remove this function after completely switching to new approach of Config loading
 func (a *AirshipCTLSettings) InitAirshipConfigPath() {
 	// The airshipConfigPath may already have been received as a command line argument
 	if a.AirshipConfigPath != "" {
@@ -91,6 +93,7 @@ func (a *AirshipCTLSettings) InitAirshipConfigPath() {
 }
 
 // InitKubeConfigPath - Initializes KubeConfigPath variable for Config object
+// TODO (raliev) remove this function after completely switching to new approach of Config loading
 func (a *AirshipCTLSettings) InitKubeConfigPath() {
 	// NOTE(howell): This function will set the kubeConfigPath to the
 	// default location under the airship directory unless the user