add users string method

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/types/users.go

@@ -3,8 +3,10 @@ package types
 import (
 	"cmp"
 	"database/sql"
+	"fmt"
 	"net/mail"
 	"strconv"
+	"strings"
 
 	v1 "github.com/juanfont/headscale/gen/go/headscale/v1"
 	"github.com/juanfont/headscale/hscontrol/util"
@@ -15,6 +17,19 @@ import (
 
 type UserID uint64
 
+type Users []User
+
+func (u Users) String() string {
+	var sb strings.Builder
+	sb.WriteString("[ ")
+	for _, user := range u {
+		fmt.Fprintf(&sb, "%d: %s, ", user.ID, user.Name)
+	}
+	sb.WriteString(" ]")
+
+	return sb.String()
+}
+
 // User is the way Headscale implements the concept of users in Tailscale
 //
 // At the end of the day, users in Tailscale are some kind of 'bubbles' or users
@@ -57,7 +72,12 @@ type User struct {
 // should be used throughout headscale, in information returned to the
 // user and the Policy engine.
 func (u *User) Username() string {
-	return cmp.Or(u.Email, u.Name, u.ProviderIdentifier.String, strconv.FormatUint(uint64(u.ID), 10))
+	return cmp.Or(
+		u.Email,
+		u.Name,
+		u.ProviderIdentifier.String,
+		strconv.FormatUint(uint64(u.ID), 10),
+	)
 }
 
 // DisplayNameOrUsername returns the DisplayName if it exists, otherwise