Remove the custom current user lookup function (#52144)

We added this function to mitigate slow user.Current() calls in
Windows Active Directory environments. Go 1.24 ships with an optimized
verison of user.Current, rendering this utility unnecessary.

Closes #41922

Author: zmb3

api/profile/profile.go

@@ -23,6 +23,7 @@ import (
 	"io/fs"
 	"net"
 	"os"
+	"os/user"
 	"path/filepath"
 	"strings"
 	"time"
@@ -32,7 +33,6 @@ import (
 	"gopkg.in/yaml.v2"
 
 	"github.com/gravitational/teleport/api/defaults"
-	"github.com/gravitational/teleport/api/utils"
 	"github.com/gravitational/teleport/api/utils/keypaths"
 	"github.com/gravitational/teleport/api/utils/keys"
 	"github.com/gravitational/teleport/api/utils/sshutils"
@@ -359,7 +359,7 @@ func defaultProfilePath() string {
 	}
 
 	home = os.TempDir()
-	if u, err := utils.CurrentUser(); err == nil && u.HomeDir != "" {
+	if u, err := user.Current(); err == nil && u.HomeDir != "" {
 		home = u.HomeDir
 	}
 	return filepath.Join(home, profileDir)

api/utils/user.go

@@ -78,11 +78,14 @@ are not logged in to Teleport or may not have access to a browser.
 
 ## `tsh` is very slow on Windows, what to do?
 
-If your host machine is joined to an Active Directory domain, you might find user lookups take a
-lot longer than you expect. The number of Active Directory accounts that must be scanned to
-perform a user lookup can cause tsh to hang waiting to get information about the current user.
-To fix this issue, you can use environment variables to set default account information for your
-Teleport user. If you are experiencing long lookup times on Windows, do the following:
+If your host machine is joined to an Active Directory domain, you might find
+user lookups take a lot longer than you expect. If possible, we recommend
+updating `tsh` to v18 or later, which contains an optimized user lookup
+algorithm.
+
+If upgrading is not possible, you can use environment variables to set default
+account information for your Teleport user. If you are experiencing long lookup
+times on Windows, do the following:
 
 - Either set the `TELEPORT_USER` environment variable or set the `--user` flag to the name of your Teleport user.
 - Either set the `TELEPORT_LOGIN` environment variable or set the `--login` flag to the name of current host user. This setting can be overridden if you open a new SSH session on a machine as a different user.

api/utils/user_test.go

@@ -31,6 +31,7 @@ import (
 	"net"
 	"net/url"
 	"os"
+	"os/user"
 	"path/filepath"
 	"runtime"
 	"slices"
@@ -4866,7 +4867,7 @@ func connectToSSHAgent() agent.ExtendedAgent {
 
 // Username returns the current user's username
 func Username() (string, error) {
-	u, err := apiutils.CurrentUser()
+	u, err := user.Current()
 	if err != nil {
 		return "", trace.Wrap(err)
 	}

docs/pages/faq.mdx

@@ -20,14 +20,14 @@ package mysql
 
 import (
 	"os"
+	"os/user"
 	"path/filepath"
 	"strconv"
 	"strings"
 
 	"github.com/gravitational/trace"
 	"gopkg.in/ini.v1"
 
-	"github.com/gravitational/teleport/api/utils"
 	"github.com/gravitational/teleport/lib/client/db/profile"
 )
 
@@ -51,7 +51,7 @@ type OptionFile struct {
 func DefaultConfigPath() (string, error) {
 	home, err := os.UserHomeDir()
 	if err != nil || home == "" {
-		usr, err := utils.CurrentUser()
+		usr, err := user.Current()
 		if err != nil {
 			return "", trace.ConvertSystemError(err)
 		}

lib/client/api.go

@@ -20,14 +20,14 @@ package postgres
 
 import (
 	"os"
+	"os/user"
 	"path/filepath"
 	"strconv"
 	"strings"
 
 	"github.com/gravitational/trace"
 	"gopkg.in/ini.v1"
 
-	"github.com/gravitational/teleport/api/utils"
 	"github.com/gravitational/teleport/lib/client/db/profile"
 )
 
@@ -52,7 +52,7 @@ func defaultConfigPath() (string, error) {
 	// TODO(r0mant): Check PGSERVICEFILE and PGSYSCONFDIR env vars as well.
 	home, err := os.UserHomeDir()
 	if err != nil || home == "" {
-		usr, err := utils.CurrentUser()
+		usr, err := user.Current()
 		if err != nil {
 			return "", trace.ConvertSystemError(err)
 		}

lib/client/db/mysql/optionfile.go

@@ -29,14 +29,13 @@ import (
 	"net"
 	"os"
 	"os/exec"
+	"os/user"
 	"regexp"
 	"strconv"
 	"strings"
 
 	"github.com/Microsoft/go-winio"
 	"github.com/gravitational/trace"
-
-	apiutils "github.com/gravitational/teleport/api/utils"
 )
 
 const namedPipe = `\\.\pipe\openssh-ssh-agent`
@@ -104,7 +103,7 @@ func dialCygwin(socket string) (net.Conn, error) {
 	}
 	key := sockMatches[3]
 
-	u, err := apiutils.CurrentUser()
+	u, err := user.Current()
 	if err != nil {
 		return nil, trace.Wrap(err)
 	}

lib/client/db/postgres/servicefile.go

@@ -31,6 +31,7 @@ import (
 	"os"
 	"os/exec"
 	"os/signal"
+	"os/user"
 	"path/filepath"
 	"regexp"
 	"runtime"
@@ -66,7 +67,6 @@ import (
 	"github.com/gravitational/teleport/api/types/accesslist"
 	apievents "github.com/gravitational/teleport/api/types/events"
 	"github.com/gravitational/teleport/api/types/wrappers"
-	apiutils "github.com/gravitational/teleport/api/utils"
 	"github.com/gravitational/teleport/api/utils/keys"
 	"github.com/gravitational/teleport/api/utils/prompt"
 	"github.com/gravitational/teleport/lib/asciitable"
@@ -3813,7 +3813,7 @@ func onSSHLatency(cf *CLIConf) error {
 func runLocalCommand(hostLogin string, command []string) error {
 	if len(command) == 0 {
 		if hostLogin == "" {
-			user, err := apiutils.CurrentUser()
+			user, err := user.Current()
 			if err != nil {
 				return trace.Wrap(err)
 			}