Migrate to slog for the logging package

log/slog is a new package added in Go 1.21 which supports structured
logging.

internal/auth/auth.go

@@ -7,11 +7,10 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"strings"
 
-	"go.uber.org/zap"
-
 	"safer.place/internal/database"
 )
 
@@ -27,7 +26,7 @@ type githubTokenResponse struct {
 // but if needed this can be expanded.
 type Config struct {
 	Handler      http.Handler
-	Log          *zap.Logger
+	Log          *slog.Logger
 	Domain       string
 	ClientID     string
 	ClientSecret string
@@ -41,7 +40,7 @@ type Auth struct {
 	mux         *http.ServeMux
 	cfg         *Config
 	client      *http.Client
-	log         *zap.Logger
+	log         *slog.Logger
 	db          database.Database
 }
 
@@ -69,8 +68,8 @@ func Register(prefix string, cfg *Config) func() (string, http.Handler) {
 	a.mux.HandleFunc("/", a.index)
 
 	cfg.Log.Info("authentication set up",
-		zap.String("prefix", prefix),
-		zap.String("callback", a.callbackURL),
+		slog.String("prefix", prefix),
+		slog.String("callback", a.callbackURL),
 	)
 
 	return func() (string, http.Handler) {
@@ -91,7 +90,8 @@ func (a *Auth) index(w http.ResponseWriter, r *http.Request) {
 }
 
 func (a *Auth) callback(w http.ResponseWriter, r *http.Request) {
-	a.log.Info("callback")
+	ctx := r.Context()
+	a.log.DebugContext(ctx, "callback")
 	code := r.URL.Query().Get("code")
 
 	if code == "" {
@@ -105,8 +105,7 @@ func (a *Auth) callback(w http.ResponseWriter, r *http.Request) {
 		"code":          code,
 	})
 
-	req, err := http.NewRequestWithContext(
-		r.Context(),
+	req, err := http.NewRequestWithContext(ctx,
 		http.MethodPost,
 		"https://github.com/login/oauth/access_token",
 		bytes.NewBuffer(requestData),
@@ -118,15 +117,15 @@ func (a *Auth) callback(w http.ResponseWriter, r *http.Request) {
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Accept", "application/json")
 
-	a.log.Info("sending the request to github to validate code")
+	a.log.DebugContext(ctx, "sending the request to github to validate code")
 
 	resp, err := a.client.Do(req)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusUnauthorized)
 		return
 	}
 
-	a.log.Info("request validated")
+	a.log.DebugContext(ctx, "request validated")
 
 	var tokenData githubTokenResponse
 	if err := json.NewDecoder(resp.Body).Decode(&tokenData); err != nil {
@@ -154,29 +153,35 @@ func (a *Auth) callback(w http.ResponseWriter, r *http.Request) {
 }
 
 func (a *Auth) authenticated(r *http.Request) (bool, error) {
+	ctx := r.Context()
 	cookie, err := r.Cookie("Authorization")
 	if err != nil {
-		a.log.Info("cookie not found")
+		a.log.DebugContext(ctx, "cookie not found")
 		return false, nil
 	}
 
-	a.log.Info("checking if cookie", zap.Any("cookie", cookie))
+	a.log.DebugContext(ctx, "checking if cookie",
+		slog.Any("cookie", cookie),
+	)
 
 	bearerToken := strings.Split(cookie.Value, " ")
 	if len(bearerToken) != 2 {
-		a.log.Info("not in 2 parts")
+		a.log.WarnContext(ctx, "token is not composed of 2 parts")
 		return false, ErrBadFormat
 	}
 
 	if bearerToken[0] != "Bearer" {
-		a.log.Info("bad format")
+		a.log.WarnContext(ctx, "token does not contain Bearer")
 		return false, ErrBadFormat
 	}
 
 	session := bearerToken[1]
 
-	if err := a.db.IsValidSession(r.Context(), session); err != nil {
-		a.log.Error("unable to authenticate", zap.String("session", session), zap.Error(err))
+	if err := a.db.IsValidSession(ctx, session); err != nil {
+		a.log.WarnContext(ctx, "unable to authenticate",
+			slog.String("session", session),
+			"error", err,
+		)
 		return false, nil
 	}
 

internal/cmd/saferplace/components.go

@@ -5,8 +5,8 @@ import (
 	"fmt"
 	"slices"
 
-	"go.uber.org/zap"
 	"golang.org/x/exp/maps"
+	"golang.org/x/exp/slog"
 	"golang.org/x/sync/errgroup"
 	"safer.place/internal/config"
 	"safer.place/internal/review"
@@ -130,7 +130,7 @@ func createServices(ctx context.Context, cfg *config.Config, wantedComponents []
 
 func registerConsumer(ctx context.Context, cfg *config.Config, deps *dependencies, eg *errgroup.Group) error {
 	consumer := review.New(
-		deps.logger.With(zap.String("component", "review")),
+		deps.logger.With(slog.String("component", "review")),
 		deps.queue,
 		deps.database,
 		deps.notifer,
@@ -146,20 +146,20 @@ func registerConsumer(ctx context.Context, cfg *config.Config, deps *dependencie
 func registerReview(_ context.Context, _ *config.Config, deps *dependencies) (service.Service, error) {
 	return reviewv1.Register(
 		deps.database,
-		deps.logger.With(zap.String("service", "reviewv1")),
+		deps.logger.With(slog.String("service", "reviewv1")),
 	), nil
 }
 
 func registerReport(_ context.Context, _ *config.Config, deps *dependencies) (service.Service, error) {
 	return reportv1.Register(
 		deps.queue,
-		deps.logger.With(zap.String("service", "reportv1")),
+		deps.logger.With(slog.String("service", "reportv1")),
 	), nil
 }
 
 func registerUploader(_ context.Context, _ *config.Config, deps *dependencies) (service.Service, error) {
 	return imageupload.Register(
-		imageupload.Logger(deps.logger.With(zap.String("service", "imageupload"))),
+		imageupload.Logger(deps.logger.With(slog.String("service", "imageupload"))),
 		imageupload.Tracer(deps.tracing.Tracer("imageupload")),
 		imageupload.Storage(deps.storage),
 	), nil
@@ -168,6 +168,6 @@ func registerUploader(_ context.Context, _ *config.Config, deps *dependencies) (
 func registerViewer(_ context.Context, _ *config.Config, deps *dependencies) (service.Service, error) {
 	return viewerv1.Register(
 		deps.database,
-		deps.logger.With(zap.String("service", "viewerv1")),
+		deps.logger.With(slog.String("service", "viewerv1")),
 	), nil
 }

internal/cmd/saferplace/dependencies.go

@@ -6,6 +6,8 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log/slog"
+	"os"
 	"slices"
 	"time"
 
@@ -15,10 +17,9 @@ import (
 	"github.com/saferplace/webserver-go/certificate"
 	"github.com/saferplace/webserver-go/certificate/insecure"
 	"github.com/saferplace/webserver-go/certificate/temporary"
-
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
-	"go.uber.org/zap"
+
 	"safer.place/internal/config"
 	"safer.place/internal/database"
 	"safer.place/internal/database/sqldatabase"
@@ -42,13 +43,13 @@ const (
 	NotifierDependency Dependency = "notifier"
 )
 
-func dependenciesToStrings(dependencies []Dependency) []string {
-	res := make([]string, 0, len(dependencies))
-	for _, dependency := range dependencies {
-		res = append(res, string(dependency))
-	}
-	return res
-}
+// func dependenciesToStrings(dependencies []Dependency) []string {
+// 	res := make([]string, 0, len(dependencies))
+// 	for _, dependency := range dependencies {
+// 		res = append(res, string(dependency))
+// 	}
+// 	return res
+// }
 
 // StringsToDependencies converts a string slice into dependecy slice
 func StringsToDependencies(ss []string) []Dependency {
@@ -74,7 +75,7 @@ type dependencies struct {
 	// always created dependencies
 	tracing trace.TracerProvider
 	metrics *prometheus.Registry
-	logger  *zap.Logger
+	logger  *slog.Logger
 
 	// dynamically created dependencies
 	database database.Database
@@ -93,7 +94,7 @@ func createDependencies(ctx context.Context, cfg *config.Config, components []Co
 		metrics: prometheus.NewRegistry(),
 	}
 
-	mc := multiCloser{closer(func() error { return deps.logger.Sync() })}
+	mc := multiCloser{}
 
 	tracing, tracingCloser, err := tracing.NewTracingProvider(ctx, cfg.Tracing)
 	if err != nil {
@@ -102,9 +103,9 @@ func createDependencies(ctx context.Context, cfg *config.Config, components []Co
 	mc = append(mc, tracingCloser)
 	deps.tracing = tracing
 
-	deps.logger.Debug("initializing dependencies",
-		zap.Strings("components", ComponentsToStrings(components)),
-		zap.Strings("dependencies", dependenciesToStrings(wantedDependencies)),
+	deps.logger.DebugContext(ctx, "initializing dependencies",
+		"components", components,
+		"dependencies", wantedDependencies,
 	)
 
 	deps.metrics.MustRegister(
@@ -212,7 +213,7 @@ func registerStorage(ctx context.Context, cfg *config.Config, deps *dependencies
 
 func registerNotifier(_ context.Context, cfg *config.Config, deps *dependencies) (err error) {
 	var v notifier.Notifier
-	log := deps.logger.With(zap.String("notifier", cfg.Notifier.Provider))
+	log := deps.logger.With(slog.String("notifier", cfg.Notifier.Provider))
 	switch cfg.Notifier.Provider {
 	case "log":
 		v = lognotifier.New(log)
@@ -228,28 +229,26 @@ func registerNotifier(_ context.Context, cfg *config.Config, deps *dependencies)
 	return nil
 }
 
-func newLogger(cfg *config.Config) *zap.Logger {
-	var logger *zap.Logger
+func newLogger(cfg *config.Config) *slog.Logger {
+	var logger *slog.Logger
 	if cfg.Debug {
-		logger, _ = zap.NewDevelopment()
-		logger.Debug("debug mode enabled")
+		logger = slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+			Level:     slog.LevelDebug,
+			AddSource: true,
+		}))
 	} else {
-		logger, _ = zap.NewProduction()
+		logger = slog.New(slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{
+			Level: slog.LevelInfo,
+		}))
 	}
 
 	logger.Debug("using configuration",
-		zap.Any("config", cfg),
+		slog.Any("config", cfg),
 	)
 
 	return logger
 }
 
-type closer func() error
-
-func (c closer) Close() error {
-	return c()
-}
-
 type multiCloser []io.Closer
 
 func (mc multiCloser) Close() error {

internal/cmd/saferplace/saferplace.go

@@ -12,7 +12,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/saferplace/webserver-go"
 	"github.com/saferplace/webserver-go/middleware"
-	"go.uber.org/zap"
 	"golang.org/x/sync/errgroup"
 	"safer.place/internal/auth"
 	"safer.place/internal/config"
@@ -84,7 +83,8 @@ func Run(ctx context.Context, components []Component, cfg *config.Config) (err e
 	}
 
 	srv, err := webserver.New(
-		webserver.Logger(deps.logger.With(zap.String("component", "server"))),
+		// TODO: Enable slog in webserver
+		// webserver.Logger(deps.logger.With(slog.String("component", "server"))),
 		webserver.Services(services...),
 		webserver.TLSConfig(tlsConfig),
 		webserver.Middlewares(middlewares...),

internal/config/config.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/kelseyhightower/envconfig"
+	"golang.org/x/exp/slog"
 	"gopkg.in/yaml.v3"
 	"safer.place/internal/database/sqldatabase"
 	"safer.place/internal/storage/minio"
@@ -27,6 +28,10 @@ type Config struct {
 	Notifier  NotifierConfig  `yaml:"notifier"`
 }
 
+func (c Config) LogValue() slog.Value {
+	return slog.StringValue(fmt.Sprintf("%+v", c))
+}
+
 // WebserverConfig contains all configuration used to setup the webserver and middleware
 type WebserverConfig struct {
 	Port        int        `yaml:"port" envconfig:"PORT" default:"8001"`
@@ -127,6 +132,10 @@ func (d *Duration) UnmarshalText(text []byte) error {
 	return nil
 }
 
-func (d *Duration) String() string {
-	return time.Duration(*d).String()
+func (d Duration) LogValue() slog.Value {
+	return slog.DurationValue(time.Duration(d))
+}
+
+func (d Duration) String() string {
+	return time.Duration(d).String()
 }

internal/config/secret/secret.go

@@ -0,0 +1,12 @@
+package secret
+
+import "log/slog"
+
+// Secret hides secrets which do not want to log by accident.
+type Secret string
+
+// LogValue implements slog.LogValuer.
+// It avoids revealing the token.
+func (Secret) LogValue() slog.Value {
+	return slog.StringValue("<redacted>")
+}

internal/notifier/discordnotifier/discordnotifier.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"log"
 	"net/http"
 
 	"github.com/bwmarrin/discordgo"
@@ -56,13 +55,14 @@ func (n *Notifier) Notify(ctx context.Context, i *incident.Incident) error {
 		return fmt.Errorf("unable to encode webhook body: %w", err)
 	}
 
-	log.Println(body)
-
-	req, err := http.NewRequest(http.MethodPost, n.endpoint, body)
+	req, err := http.NewRequestWithContext(ctx,
+		http.MethodPost,
+		n.endpoint,
+		body,
+	)
 	if err != nil {
 		return fmt.Errorf("unable to create request: %w", err)
 	}
-	req = req.WithContext(ctx)
 	req.Header.Set("Content-Type", "application/json")
 
 	resp, err := n.client.Do(req)