Add pulumi whoami

It's often helpful to understand the user the CLI thinks you are
logged in as, so let's add a command that does that.

Fixes #1507

cmd/login.go

@@ -46,7 +46,12 @@ func newLoginCmd() *cobra.Command {
 				return err
 			}
 
-			fmt.Printf("Logged into %s\n", b.Name())
+			if currentUser, err := b.CurrentUser(); err == nil {
+				fmt.Printf("Logged into %s as %s\n", b.Name(), currentUser)
+			} else {
+				fmt.Printf("Logged into %s\n", b.Name())
+			}
+
 			return nil
 		}),
 	}

cmd/pulumi.go

@@ -114,6 +114,7 @@ func NewPulumiCmd() *cobra.Command {
 	cmd.AddCommand(newStackCmd())
 	cmd.AddCommand(newUpdateCmd())
 	cmd.AddCommand(newVersionCmd())
+	cmd.AddCommand(newWhoAmICmd())
 
 	// Less common, and thus hidden, commands:
 	cmd.AddCommand(newGenBashCompletionCmd(cmd))

cmd/whoami.go

@@ -0,0 +1,50 @@
+// Copyright 2016-2018, Pulumi Corporation.
+//
+// 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 cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	"github.com/pulumi/pulumi/pkg/util/cmdutil"
+)
+
+func newWhoAmICmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "whoami",
+		Short: "Display current logged in user",
+		Long: "Display current logged in user\n" +
+			"\n" +
+			"Displays the username of the currently logged in user.",
+		Args: cmdutil.NoArgs,
+		Run: cmdutil.RunFunc(func(cmd *cobra.Command, args []string) error {
+			b, err := currentBackend()
+			if err != nil {
+				return err
+			}
+
+			name, err := b.CurrentUser()
+			if err != nil {
+				return err
+			}
+
+			fmt.Println(name)
+			return nil
+		}),
+	}
+
+	return cmd
+}

pkg/backend/backend.go

@@ -101,6 +101,8 @@ type Backend interface {
 	ImportDeployment(ctx context.Context, stackRef StackReference, deployment *apitype.UntypedDeployment) error
 	// Logout logs you out of the backend and removes any stored credentials.
 	Logout() error
+	// Returns the identity of the current user for the backend.
+	CurrentUser() (string, error)
 }
 
 // UpdateOptions is the full set of update options, including backend and engine options.

pkg/backend/cloud/backend.go

@@ -325,6 +325,10 @@ func (b *cloudBackend) Name() string {
 	return b.url
 }
 
+func (b *cloudBackend) CurrentUser() (string, error) {
+	return b.client.GetPulumiAccountName(context.Background())
+}
+
 func (b *cloudBackend) CloudURL() string { return b.url }
 
 func (b *cloudBackend) ParseStackReference(s string) (backend.StackReference, error) {

pkg/backend/local/backend.go

@@ -410,6 +410,10 @@ func (b *localBackend) Logout() error {
 	return workspace.DeleteAccessToken(b.url)
 }
 
+func (b *localBackend) CurrentUser() (string, error) {
+	return "", errors.New("the local backend does not support multiple users")
+}
+
 func (b *localBackend) getLocalStacks() ([]tokens.QName, error) {
 	var stacks []tokens.QName