kd: add "credential use" command

go/src/koding/klientctl/credential.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -252,14 +253,37 @@ func CredentialDescribe(c *cli.Context, log logging.Logger, _ string) (int, erro
 	return 0, nil
 }
 
+func CredentialUse(c *cli.Context, _ logging.Logger, _ string) (int, error) {
+	if c.NArg() != 1 {
+		cli.ShowCommandHelp(c, "use")
+		return 1, errors.New("missing argument")
+	}
+
+	arg := c.Args().Get(0)
+
+	if err := credential.Use(arg); err != nil {
+		return 1, errors.New("error changing default credential: " + err.Error())
+	}
+
+	return 0, nil
+}
+
 func printCreds(creds []stack.CredentialItem) {
 	w := tabwriter.NewWriter(os.Stdout, 2, 0, 2, ' ', 0)
 	defer w.Flush()
 
-	fmt.Fprintln(w, "ID\tTITLE\tTEAM\tPROVIDER")
+	used := credential.Used()
+
+	fmt.Fprintln(w, "ID\tTITLE\tTEAM\tPROVIDER\tUSED")
 
 	for _, cred := range creds {
-		fmt.Fprintf(w, "%s\t%s\t%s\t%s\n", cred.Identifier, cred.Title, cred.Team, cred.Provider)
+		isused := "-"
+
+		if ident, ok := used[cred.Provider]; ok && cred.Identifier == ident {
+			isused = "default"
+		}
+
+		fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\n", cred.Identifier, cred.Title, cred.Team, cred.Provider, isused)
 	}
 }
 

go/src/koding/klientctl/endpoint/credential/credential.go

@@ -54,7 +54,7 @@ type Client struct {
 func (c *Client) List(opts *ListOptions) (stack.Credentials, error) {
 	c.init()
 
-	var req *stack.CredentialListRequest
+	var req = &stack.CredentialListRequest{}
 	var resp stack.CredentialListResponse
 
 	if opts != nil {

go/src/koding/klientctl/main.go

@@ -530,6 +530,10 @@ func run(args []string) {
 							Usage: "Specify credential title.",
 						},
 					},
+				}, {
+					Name:   "use",
+					Usage:  "Change default credential per provider.",
+					Action: ctlcli.ExitErrAction(CredentialUse, log, "use"),
 				}, {
 					Name:   "describe",
 					Usage:  "Describe credential documents.",