Add the ability to send logs to a syslog daemon.

src/observe.go

@@ -13,10 +13,13 @@ import (
 	"runtime/debug"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	slogmulti "github.com/samber/slog-multi"
 
+	syslog "codeberg.org/git-pages/go-slog-syslog"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 
@@ -42,6 +45,8 @@ var (
 	}, []string{"method"})
 )
 
+var syslogHandler syslog.Handler
+
 func hasSentry() bool {
 	return os.Getenv("SENTRY_DSN") != ""
 }
@@ -83,6 +88,19 @@ func InitObservability() {
 		log.Println("unknown log format", config.LogFormat)
 	}
 
+	if syslogAddr := os.Getenv("SYSLOG_ADDR"); syslogAddr != "" {
+		var err error
+		syslogHandler, err = syslog.NewHandler(&syslog.HandlerOptions{
+			Address:          syslogAddr,
+			AppName:          "git-pages",
+			StructuredDataID: "git-pages",
+		})
+		if err != nil {
+			log.Fatalf("syslog: %v", err)
+		}
+		logHandlers = append(logHandlers, syslogHandler)
+	}
+
 	if hasSentry() {
 		enableLogs := false
 		if value, err := strconv.ParseBool(os.Getenv("SENTRY_LOGS")); err == nil {
@@ -154,9 +172,15 @@ func levelsFromMinimum(minLevel slog.Level) []slog.Level {
 }
 
 func FiniObservability() {
-	if hasSentry() {
-		sentry.Flush(2 * time.Second)
+	var wg sync.WaitGroup
+	timeout := 2 * time.Second
+	if syslogHandler != nil {
+		wg.Go(func() { syslogHandler.Flush(timeout) })
 	}
+	if hasSentry() {
+		wg.Go(func() { sentry.Flush(timeout) })
+	}
+	wg.Wait()
 }
 
 func ObserveError(err error) {