Switch log handling to slog.

This currently doesn't add any structure to the logs, changing just
the handler and output format. It does also add Sentry logging support.

The `log-format` configuration value now accepts values `none`, `text`,
and `json`.

src/config.go

@@ -37,7 +37,7 @@ func (t *Duration) MarshalText() ([]byte, error) {
 type Config struct {
 	Insecure  bool             `toml:"-" env:"insecure"`
 	Features  []string         `toml:"features"`
-	LogFormat string           `toml:"log-format" default:"datetime+message"`
+	LogFormat string           `toml:"log-format" default:"text"`
 	Server    ServerConfig     `toml:"server"`
 	Wildcard  []WildcardConfig `toml:"wildcard"`
 	Storage   StorageConfig    `toml:"storage"`

src/main.go

@@ -71,9 +71,6 @@ func serve(listener net.Listener, handler http.Handler) {
 }
 
 func main() {
-	InitObservability()
-	defer FiniObservability()
-
 	printConfigEnvVars := flag.Bool("print-config-env-vars", false,
 		"print every recognized configuration environment variable and exit")
 	printConfig := flag.Bool("print-config", false,
@@ -107,12 +104,8 @@ func main() {
 		return
 	}
 
-	switch config.LogFormat {
-	case "message":
-		log.SetFlags(0)
-	case "datetime+message":
-		log.SetFlags(log.Ldate | log.Ltime | log.LUTC)
-	}
+	InitObservability()
+	defer FiniObservability()
 
 	if len(config.Features) > 0 {
 		log.Println("features:", strings.Join(config.Features, ", "))

src/observe.go

@@ -1,16 +1,22 @@
 package main
 
 import (
+	"context"
 	"log"
+	"log/slog"
 	"net/http"
 	"os"
 	"runtime/debug"
+	"strconv"
 	"time"
 
 	"github.com/honeybadger-io/honeybadger-go"
 
 	"github.com/getsentry/sentry-go"
 	sentryhttp "github.com/getsentry/sentry-go/http"
+	sentryslog "github.com/getsentry/sentry-go/slog"
+
+	slogmulti "github.com/samber/slog-multi"
 )
 
 func hasHoneybadger() bool {
@@ -27,6 +33,21 @@ func InitObservability() {
 		environment = value
 	}
 
+	logHandlers := []slog.Handler{}
+
+	switch config.LogFormat {
+	case "none":
+		// nothing to do
+	case "text":
+		logHandlers = append(logHandlers,
+			slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{}))
+	case "json":
+		logHandlers = append(logHandlers,
+			slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{}))
+	default:
+		log.Println("unknown log format", config.LogFormat)
+	}
+
 	if hasHoneybadger() {
 		honeybadger.Configure(honeybadger.Configuration{
 			Env: environment,
@@ -35,13 +56,27 @@ func InitObservability() {
 	}
 
 	if hasSentry() {
+		enableLogs := false
+		if value, err := strconv.ParseBool(os.Getenv("SENTRY_LOGS")); err == nil {
+			enableLogs = value
+		}
+
 		options := sentry.ClientOptions{}
-		options.Environment = environment
 		options.Dsn = os.Getenv("SENTRY_DSN")
+		options.Environment = environment
+		options.EnableLogs = enableLogs
 		if err := sentry.Init(options); err != nil {
 			log.Fatalf("sentry: %s\n", err)
 		}
+
+		if enableLogs {
+			logHandlers = append(logHandlers, sentryslog.Option{
+				AddSource: true,
+			}.NewSentryHandler(context.Background()))
+		}
 	}
+
+	slog.SetDefault(slog.New(slogmulti.Fanout(logHandlers...)))
 }
 
 func FiniObservability() {