Remove logrus dependency

This is the _last_ step required to migrate from logrus to slog.
All components in the repository have been migrated to use slog
allowing the logrus formatter to be deleted.

The slog handler tests that validate the output have been updated
to assert the format directly instead of comparing it to the output
from the logrus formatter.

.golangci.yml

@@ -115,14 +115,6 @@ linters-settings:
             desc: 'use "crypto" or "x/crypto" instead'
       # Prevent importing any additional logging libraries.
       logging:
-        files:
-          # 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 exception when said formatter is deleted.
-          - '!**/lib/utils/log/**'
-          - '!**/lib/utils/cli.go'
         deny:
           - pkg: github.com/sirupsen/logrus
             desc: 'use "log/slog" instead'

go.mod

@@ -179,7 +179,6 @@ require (
 	github.com/sigstore/cosign/v2 v2.4.1
 	github.com/sigstore/sigstore v1.8.11
 	github.com/sijms/go-ora/v2 v2.8.22
-	github.com/sirupsen/logrus v1.9.3
 	github.com/snowflakedb/gosnowflake v1.12.1
 	github.com/spf13/cobra v1.8.1
 	github.com/spiffe/go-spiffe/v2 v2.4.0
@@ -501,6 +500,7 @@ require (
 	github.com/sigstore/protobuf-specs v0.3.2 // indirect
 	github.com/sigstore/rekor v1.3.6 // indirect
 	github.com/sigstore/timestamp-authority v1.2.2 // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
 	github.com/spf13/cast v1.7.0 // indirect

integrations/terraform/go.mod

@@ -21,7 +21,7 @@ require (
 	github.com/hashicorp/terraform-plugin-log v0.9.0
 	github.com/hashicorp/terraform-plugin-sdk/v2 v2.10.1
 	github.com/jonboulle/clockwork v0.4.0
-	github.com/sirupsen/logrus v1.9.3
+	github.com/sirupsen/logrus v1.9.3 // indirect
 	github.com/stretchr/testify v1.10.0
 	google.golang.org/grpc v1.69.2
 	google.golang.org/protobuf v1.36.2

lib/client/api.go

@@ -2853,7 +2853,7 @@ type execResult struct {
 
 // 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.
+// by multiple command runners.
 type sharedWriter struct {
 	mu sync.Mutex
 	io.Writer

lib/srv/desktop/rdp/rdpclient/client.go

@@ -93,7 +93,7 @@ func init() {
 	var rustLogLevel string
 
 	// initialize the Rust logger by setting $RUST_LOG based
-	// on the logrus log level
+	// on the slog log level
 	// (unless RUST_LOG is already explicitly set, then we
 	// assume the user knows what they want)
 	rl := os.Getenv("RUST_LOG")

lib/utils/cli.go

@@ -26,7 +26,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	stdlog "log"
 	"log/slog"
 	"os"
 	"runtime"
@@ -38,7 +37,6 @@ import (
 
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/gravitational/trace"
-	"github.com/sirupsen/logrus"
 	"golang.org/x/term"
 
 	"github.com/gravitational/teleport"
@@ -100,59 +98,18 @@ func InitLogger(purpose LoggingPurpose, level slog.Level, opts ...LoggerOption)
 		opt(&o)
 	}
 
-	logrus.StandardLogger().ReplaceHooks(make(logrus.LevelHooks))
-	logrus.SetLevel(logutils.SlogLevelToLogrusLevel(level))
-
-	var (
-		w            io.Writer
-		enableColors bool
-	)
-	switch purpose {
-	case LoggingForCLI:
-		// If debug logging was asked for on the CLI, then write logs to stderr.
-		// Otherwise, discard all logs.
-		if level == slog.LevelDebug {
-			enableColors = IsTerminal(os.Stderr)
-			w = logutils.NewSharedWriter(os.Stderr)
-		} else {
-			w = io.Discard
-			enableColors = false
-		}
-	case LoggingForDaemon:
-		enableColors = IsTerminal(os.Stderr)
-		w = logutils.NewSharedWriter(os.Stderr)
-	}
-
-	var (
-		formatter logrus.Formatter
-		handler   slog.Handler
-	)
-	switch o.format {
-	case LogFormatText, "":
-		textFormatter := logutils.NewDefaultTextFormatter(enableColors)
-
-		// Calling CheckAndSetDefaults enables the timestamp field to
-		// be included in the output. The error returned is ignored
-		// because the default formatter cannot be invalid.
-		if purpose == LoggingForCLI && level == slog.LevelDebug {
-			_ = textFormatter.CheckAndSetDefaults()
-		}
-
-		formatter = textFormatter
-		handler = logutils.NewSlogTextHandler(w, logutils.SlogTextHandlerConfig{
-			Level:        level,
-			EnableColors: enableColors,
-		})
-	case LogFormatJSON:
-		formatter = &logutils.JSONFormatter{}
-		handler = logutils.NewSlogJSONHandler(w, logutils.SlogJSONHandlerConfig{
-			Level: level,
-		})
+	// If debug or trace logging is not enabled for CLIs,
+	// then discard all log output.
+	if purpose == LoggingForCLI && level > slog.LevelDebug {
+		slog.SetDefault(slog.New(logutils.DiscardHandler{}))
+		return
 	}
 
-	logrus.SetFormatter(formatter)
-	logrus.SetOutput(w)
-	slog.SetDefault(slog.New(handler))
+	logutils.Initialize(logutils.Config{
+		Severity:     level.String(),
+		Format:       o.format,
+		EnableColors: IsTerminal(os.Stderr),
+	})
 }
 
 var initTestLoggerOnce = sync.Once{}
@@ -163,56 +120,24 @@ func InitLoggerForTests() {
 		// Parse flags to check testing.Verbose().
 		flag.Parse()
 
-		level := slog.LevelWarn
-		w := io.Discard
-		if testing.Verbose() {
-			level = slog.LevelDebug
-			w = os.Stderr
+		if !testing.Verbose() {
+			slog.SetDefault(slog.New(logutils.DiscardHandler{}))
+			return
 		}
 
-		logger := logrus.StandardLogger()
-		logger.SetFormatter(logutils.NewTestJSONFormatter())
-		logger.SetLevel(logutils.SlogLevelToLogrusLevel(level))
-
-		output := logutils.NewSharedWriter(w)
-		logger.SetOutput(output)
-		slog.SetDefault(slog.New(logutils.NewSlogJSONHandler(output, logutils.SlogJSONHandlerConfig{Level: level})))
+		logutils.Initialize(logutils.Config{
+			Severity: slog.LevelDebug.String(),
+			Format:   LogFormatJSON,
+		})
 	})
 }
 
-// NewLoggerForTests creates a new logrus logger for test environments.
-func NewLoggerForTests() *logrus.Logger {
-	InitLoggerForTests()
-	return logrus.StandardLogger()
-}
-
 // NewSlogLoggerForTests creates a new slog logger for test environments.
 func NewSlogLoggerForTests() *slog.Logger {
 	InitLoggerForTests()
 	return slog.Default()
 }
 
-// WrapLogger wraps an existing logger entry and returns
-// a value satisfying the Logger interface
-func WrapLogger(logger *logrus.Entry) Logger {
-	return &logWrapper{Entry: logger}
-}
-
-// NewLogger creates a new empty logrus logger.
-func NewLogger() *logrus.Logger {
-	return logrus.StandardLogger()
-}
-
-// Logger describes a logger value
-type Logger interface {
-	logrus.FieldLogger
-	// GetLevel specifies the level at which this logger
-	// value is logging
-	GetLevel() logrus.Level
-	// SetLevel sets the logger's level to the specified value
-	SetLevel(level logrus.Level)
-}
-
 // FatalError is for CLI front-ends: it detects gravitational/trace debugging
 // information, sends it to the logger, strips it off and prints a clean message to stderr
 func FatalError(err error) {
@@ -231,7 +156,7 @@ func GetIterations() int {
 	if err != nil {
 		panic(err)
 	}
-	logrus.Debugf("Starting tests with %v iterations.", iter)
+	slog.DebugContext(context.Background(), "Running tests multiple times due to presence of ITERATIONS environment variable", "iterations", iter)
 	return iter
 }
 
@@ -484,47 +409,6 @@ func AllowWhitespace(s string) string {
 	return sb.String()
 }
 
-// NewStdlogger creates a new stdlib logger that uses the specified leveled logger
-// for output and the given component as a logging prefix.
-func NewStdlogger(logger LeveledOutputFunc, component string) *stdlog.Logger {
-	return stdlog.New(&stdlogAdapter{
-		log: logger,
-	}, component, stdlog.LstdFlags)
-}
-
-// Write writes the specified buffer p to the underlying leveled logger.
-// Implements io.Writer
-func (r *stdlogAdapter) Write(p []byte) (n int, err error) {
-	r.log(string(p))
-	return len(p), nil
-}
-
-// stdlogAdapter is an io.Writer that writes into an instance
-// of logrus.Logger
-type stdlogAdapter struct {
-	log LeveledOutputFunc
-}
-
-// LeveledOutputFunc describes a function that emits given
-// arguments at a specific level to an underlying logger
-type LeveledOutputFunc func(args ...interface{})
-
-// GetLevel returns the level of the underlying logger
-func (r *logWrapper) GetLevel() logrus.Level {
-	return r.Entry.Logger.GetLevel()
-}
-
-// SetLevel sets the logging level to the given value
-func (r *logWrapper) SetLevel(level logrus.Level) {
-	r.Entry.Logger.SetLevel(level)
-}
-
-// logWrapper wraps a log entry.
-// Implements Logger
-type logWrapper struct {
-	*logrus.Entry
-}
-
 // needsQuoting returns true if any non-printable characters are found.
 func needsQuoting(text string) bool {
 	for _, r := range text {