Switch to slog

.golangci.yml

@@ -1,22 +1,20 @@
 linters:
   enable:
-  - goimports
-  - misspell
-  - revive
+    - goimports
+    - misspell
+    - revive
 
 issues:
   exclude-rules:
-  - path: _test.go
-    linters:
-    - errcheck
+    - path: _test.go
+      linters:
+        - errcheck
 
 linters-settings:
   errcheck:
     exclude-functions:
       # Used in HTTP handlers, any error is handled by the server itself.
       - (net/http.ResponseWriter).Write
-      # Never check for logger errors.
-      - (github.com/go-kit/log.Logger).Log
   revive:
     rules:
       # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter

go.mod

@@ -5,7 +5,6 @@ go 1.22
 require (
 	github.com/alecthomas/kingpin/v2 v2.4.0
 	github.com/coreos/go-systemd/v22 v22.5.0
-	github.com/go-kit/log v0.2.1
 	github.com/mdlayher/vsock v1.2.1
 	github.com/prometheus/common v0.58.0
 	golang.org/x/crypto v0.26.0
@@ -17,7 +16,6 @@ require (
 	github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
-	github.com/go-logfmt/logfmt v0.5.1 // indirect
 	github.com/jpillora/backoff v1.0.0 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/mdlayher/socket v0.4.1 // indirect

go.sum

@@ -12,10 +12,6 @@ github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ3
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/go-kit/log v0.2.1 h1:MRVx0/zhvdseW+Gza6N9rVzU/IVzaeE1SFI4raAhmBU=
-github.com/go-kit/log v0.2.1/go.mod h1:NwTd00d/i8cPZ3xOwwiv2PO5MOcx78fFErGNcVmBjv0=
-github.com/go-logfmt/logfmt v0.5.1 h1:otpy5pqBCBZ1ng9RQ0dPu4PN7ba75Y/aA+UpowDyNVA=
-github.com/go-logfmt/logfmt v0.5.1/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=

web/handler.go

@@ -18,11 +18,11 @@ package web
 import (
 	"encoding/hex"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"strings"
 	"sync"
 
-	"github.com/go-kit/log"
 	"golang.org/x/crypto/bcrypt"
 )
 
@@ -78,7 +78,7 @@ HeadersLoop:
 type webHandler struct {
 	tlsConfigPath string
 	handler       http.Handler
-	logger        log.Logger
+	logger        *slog.Logger
 	cache         *cache
 	// bcryptMtx is there to ensure that bcrypt.CompareHashAndPassword is run
 	// only once in parallel as this is CPU intensive.
@@ -88,7 +88,7 @@ type webHandler struct {
 func (u *webHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	c, err := getConfig(u.tlsConfigPath)
 	if err != nil {
-		u.logger.Log("msg", "Unable to parse configuration", "err", err)
+		u.logger.Error("Unable to parse configuration", "err", err.Error())
 		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
 	}

web/tls_config.go

@@ -18,6 +18,7 @@ import (
 	"crypto/x509"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net"
 	"net/http"
 	"net/url"
@@ -27,8 +28,6 @@ import (
 	"strings"
 
 	"github.com/coreos/go-systemd/v22/activation"
-	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
 	"github.com/mdlayher/vsock"
 	config_util "github.com/prometheus/common/config"
 	"golang.org/x/sync/errgroup"
@@ -267,7 +266,7 @@ func ConfigToTLSConfig(c *TLSConfig) (*tls.Config, error) {
 
 // ServeMultiple starts the server on the given listeners. The FlagConfig is
 // also passed on to Serve.
-func ServeMultiple(listeners []net.Listener, server *http.Server, flags *FlagConfig, logger log.Logger) error {
+func ServeMultiple(listeners []net.Listener, server *http.Server, flags *FlagConfig, logger *slog.Logger) error {
 	errs := new(errgroup.Group)
 	for _, l := range listeners {
 		l := l
@@ -284,13 +283,13 @@ func ServeMultiple(listeners []net.Listener, server *http.Server, flags *FlagCon
 // Or instead uses systemd socket activated listeners if WebSystemdSocket in the
 // FlagConfig is true.
 // The FlagConfig is also passed on to ServeMultiple.
-func ListenAndServe(server *http.Server, flags *FlagConfig, logger log.Logger) error {
+func ListenAndServe(server *http.Server, flags *FlagConfig, logger *slog.Logger) error {
 	if flags.WebSystemdSocket == nil && (flags.WebListenAddresses == nil || len(*flags.WebListenAddresses) == 0) {
 		return ErrNoListeners
 	}
 
 	if flags.WebSystemdSocket != nil && *flags.WebSystemdSocket {
-		level.Info(logger).Log("msg", "Listening on systemd activated listeners instead of port listeners.")
+		logger.Info("Listening on systemd activated listeners instead of port listeners.")
 		listeners, err := activation.Listeners()
 		if err != nil {
 			return err
@@ -344,11 +343,11 @@ func parseVsockPort(address string) (uint32, error) {
 
 // Server starts the server on the given listener. Based on the file path
 // WebConfigFile in the FlagConfig, TLS or basic auth could be enabled.
-func Serve(l net.Listener, server *http.Server, flags *FlagConfig, logger log.Logger) error {
-	level.Info(logger).Log("msg", "Listening on", "address", l.Addr().String())
+func Serve(l net.Listener, server *http.Server, flags *FlagConfig, logger *slog.Logger) error {
+	logger.Info("Listening on", "address", l.Addr().String())
 	tlsConfigPath := *flags.WebConfigFile
 	if tlsConfigPath == "" {
-		level.Info(logger).Log("msg", "TLS is disabled.", "http2", false, "address", l.Addr().String())
+		logger.Info("TLS is disabled.", "http2", false, "address", l.Addr().String())
 		return server.Serve(l)
 	}
 
@@ -381,10 +380,10 @@ func Serve(l net.Listener, server *http.Server, flags *FlagConfig, logger log.Lo
 			server.TLSNextProto = make(map[string]func(*http.Server, *tls.Conn, http.Handler))
 		}
 		// Valid TLS config.
-		level.Info(logger).Log("msg", "TLS is enabled.", "http2", c.HTTPConfig.HTTP2, "address", l.Addr().String())
+		logger.Info("TLS is enabled.", "http2", c.HTTPConfig.HTTP2, "address", l.Addr().String())
 	case errNoTLSConfig:
 		// No TLS config, back to plain HTTP.
-		level.Info(logger).Log("msg", "TLS is disabled.", "http2", false, "address", l.Addr().String())
+		logger.Info("TLS is disabled.", "http2", false, "address", l.Addr().String())
 		return server.Serve(l)
 	default:
 		// Invalid TLS config.
@@ -512,6 +511,6 @@ func (tv *TLSVersion) MarshalYAML() (interface{}, error) {
 // tlsConfigPath, TLS or basic auth could be enabled.
 //
 // Deprecated: Use ListenAndServe instead.
-func Listen(server *http.Server, flags *FlagConfig, logger log.Logger) error {
+func Listen(server *http.Server, flags *FlagConfig, logger *slog.Logger) error {
 	return ListenAndServe(server, flags, logger)
 }

web/tls_config_test.go

@@ -22,6 +22,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log/slog"
 	"net"
 	"net/http"
 	"os"
@@ -41,7 +42,7 @@ func OfString(i string) *string {
 
 var (
 	port       = getPort()
-	testlogger = &testLogger{}
+	testlogger = slog.New(slog.NewTextHandler(os.Stdout, nil))
 
 	ErrorMap = map[string]*regexp.Regexp{
 		"HTTP Response to HTTPS":       regexp.MustCompile(`server gave HTTP response to HTTPS client`),
@@ -74,12 +75,6 @@ var (
 	}
 )
 
-type testLogger struct{}
-
-func (t *testLogger) Log(keyvals ...interface{}) error {
-	return nil
-}
-
 func getPort() string {
 	listener, err := net.Listen("tcp", ":0")
 	if err != nil {