Remove all direct logrus usage from teleport module

The only remaining use of logrus is from integrations, which is
unfortunately imported by teleport.e, and prevents logrus from
being moved to an indirect dependency. The logrus formatter and
initialization of the logrus logger will remain in place until
integrations is using slog. To prevent any accidental inclusions
of logrus within the teleport module the depguard rules have been
updated to prohibit importing logrus. The rules also include
prohibit a few common log packages that tools like gopls might
automatically import.

.golangci.yml

@@ -99,10 +99,6 @@ linters-settings:
             desc: 'use "github.com/google/uuid" instead'
           - pkg: github.com/pborman/uuid
             desc: 'use "github.com/google/uuid" instead'
-          - pkg: github.com/siddontang/go-log/log
-            desc: 'use "github.com/sirupsen/logrus" instead'
-          - pkg: github.com/siddontang/go/log
-            desc: 'use "github.com/sirupsen/logrus" instead'
           - pkg: github.com/tj/assert
             desc: 'use "github.com/stretchr/testify/assert" instead'
           - pkg: go.uber.org/atomic
@@ -117,16 +113,29 @@ linters-settings:
             desc: 'use "github.com/gravitational/teleport/lib/msgraph" instead'
           - pkg: github.com/cloudflare/cfssl
             desc: 'use "crypto" or "x/crypto" instead'
-      # Prevent logrus from being imported by api and e. Once everything in teleport has been converted
-      # to use log/slog this should be moved into the main block above.
-      logrus:
+      # Prevent importing any additional logging libraries.
+      logging:
         files:
-          - '**/api/**'
-          - '**/e/**'
-          - '**/lib/srv/**'
+          # Integrations are still allowed to use logrus becuase they haven't
+          # been converted to slog yet. Once they use slog, remove this exception.
+          - '!**/integrations/**'
+          # The log package still contains the logrus formatter consumed by the integrations.
+          # Remove this exeception when said formatter is deleted.
+          - '!**/lib/utils/log/**'
+          - '!**/lib/utils/cli.go'
         deny:
           - pkg: github.com/sirupsen/logrus
             desc: 'use "log/slog" instead'
+          - pkg: github.com/siddontang/go-log/log
+            desc: 'use "log/slog" instead'
+          - pkg: github.com/siddontang/go/log
+            desc: 'use "log/slog" instead'
+          - pkg: github.com/mailgun/log
+            desc: 'use "log/slog" instead'
+          - pkg: github.com/saferwall/pe/log
+            desc: 'use "log/slog" instead'
+          - pkg: golang.org/x/exp/slog
+            desc: 'use "log/slog" instead'
       # Prevent importing internal packages in client tools or packages containing
       # common interfaces consumed by them that are known to bloat binaries or break builds
       # because they only support a single platform.

integration/helpers/instance.go

@@ -40,7 +40,6 @@ import (
 	"github.com/gorilla/websocket"
 	"github.com/gravitational/trace"
 	"github.com/jonboulle/clockwork"
-	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/crypto/ssh"
 
@@ -327,10 +326,6 @@ type InstanceConfig struct {
 	Priv []byte
 	// Pub is SSH public key of the instance
 	Pub []byte
-	// Log specifies the logger
-	// Deprecated: Use Logger instead
-	// TODO(tross): Delete when e is updated
-	Log utils.Logger
 	// Logger specifies the logger
 	Logger *slog.Logger
 	// Ports is a collection of instance ports.
@@ -354,10 +349,6 @@ func NewInstance(t *testing.T, cfg InstanceConfig) *TeleInstance {
 		cfg.Listeners = StandardListenerSetup(t, &cfg.Fds)
 	}
 
-	if cfg.Log == nil {
-		cfg.Log = logrus.New()
-	}
-
 	if cfg.Logger == nil {
 		cfg.Logger = slog.New(logutils.DiscardHandler{})
 	}

integration/hostuser_test.go

@@ -637,7 +637,7 @@ func TestRootLoginAsHostUser(t *testing.T) {
 		NodeName:    Host,
 		Priv:        privateKey,
 		Pub:         publicKey,
-		Log:         utils.NewLoggerForTests(),
+		Logger:      utils.NewSlogLoggerForTests(),
 	})
 
 	// Create a user that can create a host user.
@@ -735,7 +735,7 @@ func TestRootStaticHostUsers(t *testing.T) {
 		NodeName:    Host,
 		Priv:        privateKey,
 		Pub:         publicKey,
-		Log:         utils.NewLoggerForTests(),
+		Logger:      utils.NewSlogLoggerForTests(),
 	})
 
 	require.NoError(t, instance.Create(t, nil, false, nil))

lib/client/api.go

@@ -35,6 +35,7 @@ import (
 	"slices"
 	"strconv"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"time"
 	"unicode/utf8"
@@ -2850,6 +2851,21 @@ type execResult struct {
 	exitStatus int
 }
 
+// sharedWriter is an [io.Writer] implementation that protects
+// writes with a mutex. This allows a single [io.Writer] to be shared
+// by both logrus and slog without their output clobbering each other.
+type sharedWriter struct {
+	mu sync.Mutex
+	io.Writer
+}
+
+func (s *sharedWriter) Write(p []byte) (int, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	return s.Writer.Write(p)
+}
+
 // runCommandOnNodes executes a given bash command on a bunch of remote nodes.
 func (tc *TeleportClient) runCommandOnNodes(ctx context.Context, clt *ClusterClient, nodes []TargetNode, command []string) error {
 	cluster := clt.ClusterName()
@@ -2909,10 +2925,10 @@ func (tc *TeleportClient) runCommandOnNodes(ctx context.Context, clt *ClusterCli
 		}
 	}
 
-	stdout := logutils.NewSharedWriter(tc.Stdout)
+	stdout := &sharedWriter{Writer: tc.Stdout}
 	stderr := stdout
 	if tc.Stdout != tc.Stderr {
-		stderr = logutils.NewSharedWriter(tc.Stderr)
+		stderr = &sharedWriter{Writer: tc.Stderr}
 	}
 
 	for _, node := range nodes {

lib/service/service.go

@@ -56,7 +56,6 @@ import (
 	"github.com/jonboulle/clockwork"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/quic-go/quic-go"
-	"github.com/sirupsen/logrus"
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"go.opentelemetry.io/otel/attribute"
 	"golang.org/x/crypto/acme"
@@ -992,10 +991,6 @@ func NewTeleport(cfg *servicecfg.Config) (*TeleportProcess, error) {
 	}
 
 	processID := fmt.Sprintf("%v", nextProcessID())
-	cfg.Log = utils.WrapLogger(cfg.Log.WithFields(logrus.Fields{
-		teleport.ComponentKey: teleport.Component(teleport.ComponentProcess, processID),
-		"pid":                 fmt.Sprintf("%v.%v", os.Getpid(), processID),
-	}))
 	cfg.Logger = cfg.Logger.With(
 		teleport.ComponentKey, teleport.Component(teleport.ComponentProcess, processID),
 		"pid", fmt.Sprintf("%v.%v", os.Getpid(), processID),

lib/service/service_test.go

@@ -948,7 +948,6 @@ func TestTeleportProcess_reconnectToAuth(t *testing.T) {
 	cfg.Testing.ConnectFailureC = make(chan time.Duration, 5)
 	cfg.Testing.ClientTimeout = time.Millisecond
 	cfg.InstanceMetadataClient = imds.NewDisabledIMDSClient()
-	cfg.Log = utils.NewLoggerForTests()
 	cfg.Logger = utils.NewSlogLoggerForTests()
 	process, err := NewTeleport(cfg)
 	require.NoError(t, err)

lib/service/servicecfg/config.go

@@ -34,7 +34,6 @@ import (
 	"github.com/ghodss/yaml"
 	"github.com/gravitational/trace"
 	"github.com/jonboulle/clockwork"
-	"github.com/sirupsen/logrus"
 	"golang.org/x/crypto/ssh"
 
 	"github.com/gravitational/teleport"
@@ -52,7 +51,6 @@ import (
 	"github.com/gravitational/teleport/lib/sshca"
 	usagereporter "github.com/gravitational/teleport/lib/usagereporter/teleport"
 	"github.com/gravitational/teleport/lib/utils"
-	logutils "github.com/gravitational/teleport/lib/utils/log"
 )
 
 // Config contains the configuration for all services that Teleport can run.
@@ -223,10 +221,6 @@ type Config struct {
 	// Kube is a Kubernetes API gateway using Teleport client identities.
 	Kube KubeConfig
 
-	// Log optionally specifies the logger.
-	// Deprecated: use Logger instead.
-	Log utils.Logger
-
 	// Logger outputs messages using slog. The underlying handler respects
 	// the user supplied logging config.
 	Logger *slog.Logger
@@ -518,10 +512,6 @@ func ApplyDefaults(cfg *Config) {
 
 	cfg.Version = defaults.TeleportConfigVersionV1
 
-	if cfg.Log == nil {
-		cfg.Log = utils.NewLogger()
-	}
-
 	if cfg.Logger == nil {
 		cfg.Logger = slog.Default()
 	}
@@ -698,10 +688,6 @@ func applyDefaults(cfg *Config) {
 		cfg.Console = io.Discard
 	}
 
-	if cfg.Log == nil {
-		cfg.Log = logrus.StandardLogger()
-	}
-
 	if cfg.Logger == nil {
 		cfg.Logger = slog.Default()
 	}
@@ -799,7 +785,6 @@ func verifyEnabledService(cfg *Config) error {
 // If called after `config.ApplyFileConfig` or `config.Configure` it will also
 // change the global loggers.
 func (c *Config) SetLogLevel(level slog.Level) {
-	c.Log.SetLevel(logutils.SlogLevelToLogrusLevel(level))
 	c.LoggerLevel.Set(level)
 }
 

lib/service/servicecfg/config_test.go

@@ -28,7 +28,6 @@ import (
 	"testing"
 
 	"github.com/gravitational/trace"
-	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/require"
 
 	"github.com/gravitational/teleport/api/types"
@@ -651,44 +650,34 @@ func TestWebPublicAddr(t *testing.T) {
 
 func TestSetLogLevel(t *testing.T) {
 	for _, test := range []struct {
-		logLevel            slog.Level
-		expectedLogrusLevel logrus.Level
+		logLevel slog.Level
 	}{
 		{
-			logLevel:            logutils.TraceLevel,
-			expectedLogrusLevel: logrus.TraceLevel,
+			logLevel: logutils.TraceLevel,
 		},
 		{
-			logLevel:            slog.LevelDebug,
-			expectedLogrusLevel: logrus.DebugLevel,
+			logLevel: slog.LevelDebug,
 		},
 		{
-			logLevel:            slog.LevelInfo,
-			expectedLogrusLevel: logrus.InfoLevel,
+			logLevel: slog.LevelInfo,
 		},
 		{
-			logLevel:            slog.LevelWarn,
-			expectedLogrusLevel: logrus.WarnLevel,
+			logLevel: slog.LevelWarn,
 		},
 		{
-			logLevel:            slog.LevelError,
-			expectedLogrusLevel: logrus.ErrorLevel,
+			logLevel: slog.LevelError,
 		},
 	} {
 		t.Run(test.logLevel.String(), func(t *testing.T) {
 			// Create a configuration with local loggers to avoid modifying the
 			// global instances.
 			c := &Config{
-				Log:    logrus.New(),
 				Logger: slog.New(logutils.NewSlogTextHandler(io.Discard, logutils.SlogTextHandlerConfig{})),
 			}
 			ApplyDefaults(c)
 
 			c.SetLogLevel(test.logLevel)
 			require.Equal(t, test.logLevel, c.LoggerLevel.Level())
-			require.IsType(t, &logrus.Logger{}, c.Log)
-			l, _ := c.Log.(*logrus.Logger)
-			require.Equal(t, test.expectedLogrusLevel, l.GetLevel())
 		})
 	}
 }

lib/utils/log/formatter_test.go

@@ -51,7 +51,7 @@ var (
 	logErr = errors.New("the quick brown fox jumped really high")
 	addr   = fakeAddr{addr: "127.0.0.1:1234"}
 
-	fields = logrus.Fields{
+	fields = map[string]any{
 		"local":        &addr,
 		"remote":       &addr,
 		"login":        "llama",

lib/utils/log/handle_state.go

@@ -14,7 +14,6 @@ import (
 	"time"
 
 	"github.com/gravitational/trace"
-	"github.com/sirupsen/logrus"
 
 	"github.com/gravitational/teleport"
 )
@@ -114,13 +113,6 @@ func (s *handleState) appendAttr(a slog.Attr) bool {
 				}
 			}
 			return nonEmpty
-		case logrus.Fields:
-			for k, v := range fields {
-				if s.appendAttr(slog.Any(k, v)) {
-					nonEmpty = true
-				}
-			}
-			return nonEmpty
 		}
 	}