Os login (#50)

Add OS Login support + change key storage format

cloud/google.go

@@ -1,29 +1,55 @@
-package gcp
+package cloud
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 
+	"golang.org/x/oauth2/google"
 	"google.golang.org/api/compute/v1"
+	"google.golang.org/api/oslogin/v1"
 )
 
-// ComputeClient wraps the original *compute.Service
-type ComputeClient struct {
-	*compute.Service
-	Project string
+type GCPClient struct {
+	gce          *compute.Service
+	oslogin      *oslogin.Service
+	client_email string
+	Project      string
 }
 
-// NewComputeClient will initialize a GCP compute API client
-func NewComputeClient(project string) (*ComputeClient, error) {
+func NewGCPClient(project string) (*GCPClient, error) {
 	var err error
 	ctx := context.Background()
+	credentials, err := google.FindDefaultCredentials(ctx, compute.ComputeScope)
+	if err != nil {
+		err = fmt.Errorf("couldn't fetch default client credentials: %v", err)
+		return nil, err
+	}
 
-	s, err := compute.NewService(ctx)
+	var jsonCreds map[string]interface{}
+	err = json.Unmarshal(credentials.JSON, &jsonCreds)
+	if err != nil {
+		err = fmt.Errorf("couldn't decode default client credentials json: %v", err)
+		return nil, err
+	}
+
+	gce, err := compute.NewService(ctx)
 	if err != nil {
 		err = fmt.Errorf("couldn't initialize GCP client: %v", err)
 		return nil, err
 	}
-	computeService := &ComputeClient{s, project}
 
-	return computeService, nil
+	osc, err := oslogin.NewService(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &GCPClient{
+		gce:          gce,
+		oslogin:      osc,
+		client_email: jsonCreds["client_email"].(string),
+		Project:      project,
+	}
+
+	return c, nil
 }