feat: Support OTel and JSON for logs (via log/slog) (#760)

Co-authored-by: Kyle Mendell <kmendell@ofkm.us>

Dockerfile

@@ -30,7 +30,7 @@ RUN VERSION=$(cat /build/.version) \
     -tags "${BUILD_TAGS}" \
     -ldflags="-X github.com/pocket-id/pocket-id/backend/internal/common.Version=${VERSION} -buildid=${VERSION}" \
     -trimpath \
-    -o /build/pocket-id-backend \
+    -o /build/pocket-id \
     .
 
 # Stage 3: Production Image
@@ -39,7 +39,7 @@ WORKDIR /app
 
 RUN apk add --no-cache curl su-exec
 
-COPY --from=backend-builder /build/pocket-id-backend /app/pocket-id
+COPY --from=backend-builder /build/pocket-id /app/pocket-id
 COPY ./scripts/docker /app/docker
 
 RUN chmod +x /app/pocket-id && \

backend/go.mod

@@ -24,18 +24,25 @@ require (
 	github.com/joho/godotenv v1.5.1
 	github.com/lestrrat-go/httprc/v3 v3.0.0-beta2
 	github.com/lestrrat-go/jwx/v3 v3.0.1
+	github.com/lmittmann/tint v1.1.2
+	github.com/mattn/go-isatty v0.0.20
 	github.com/mileusna/useragent v1.3.5
+	github.com/orandin/slog-gorm v1.4.0
 	github.com/oschwald/maxminddb-golang/v2 v2.0.0-beta.2
+	github.com/samber/slog-gin v1.15.1
 	github.com/spf13/cobra v1.9.1
 	github.com/stretchr/testify v1.10.0
+	go.opentelemetry.io/contrib/bridges/otelslog v0.12.0
 	go.opentelemetry.io/contrib/exporters/autoexport v0.59.0
 	go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin v0.60.0
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.54.0
-	go.opentelemetry.io/otel v1.35.0
+	go.opentelemetry.io/otel v1.37.0
-	go.opentelemetry.io/otel/metric v1.35.0
+	go.opentelemetry.io/otel/log v0.13.0
+	go.opentelemetry.io/otel/metric v1.37.0
 	go.opentelemetry.io/otel/sdk v1.35.0
+	go.opentelemetry.io/otel/sdk/log v0.10.0
 	go.opentelemetry.io/otel/sdk/metric v1.35.0
-	go.opentelemetry.io/otel/trace v1.35.0
+	go.opentelemetry.io/otel/trace v1.37.0
 	golang.org/x/crypto v0.39.0
 	golang.org/x/image v0.24.0
 	golang.org/x/text v0.26.0
@@ -60,7 +67,7 @@ require (
 	github.com/gabriel-vasile/mimetype v1.4.8 // indirect
 	github.com/gin-contrib/sse v1.0.0 // indirect
 	github.com/go-asn1-ber/asn1-ber v1.5.7 // indirect
-	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
@@ -86,7 +93,6 @@ require (
 	github.com/lestrrat-go/httpcc v1.0.1 // indirect
 	github.com/lestrrat-go/option v1.0.1 // indirect
 	github.com/lib/pq v1.10.9 // indirect
-	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-sqlite3 v1.14.24 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
@@ -119,8 +125,6 @@ require (
 	go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.10.0 // indirect
 	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.35.0 // indirect
 	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.35.0 // indirect
-	go.opentelemetry.io/otel/log v0.10.0 // indirect
-	go.opentelemetry.io/otel/sdk/log v0.10.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.5.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 	golang.org/x/arch v0.14.0 // indirect

backend/go.sum

@@ -73,8 +73,8 @@ github.com/go-co-op/gocron/v2 v2.15.0/go.mod h1:ZF70ZwEqz0OO4RBXE1sNxnANy/zvwLca
 github.com/go-ldap/ldap/v3 v3.4.10 h1:ot/iwPOhfpNVgB1o+AVXljizWZ9JTp7YF5oeyONmcJU=
 github.com/go-ldap/ldap/v3 v3.4.10/go.mod h1:JXh4Uxgi40P6E9rdsYqpUtbW46D9UTjJ9QSwGRznplY=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
-github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
+github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
-github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
@@ -181,6 +181,8 @@ github.com/lestrrat-go/option v1.0.1 h1:oAzP2fvZGQKWkvHa1/SAcFolBEca1oN+mQ7eooNB
 github.com/lestrrat-go/option v1.0.1/go.mod h1:5ZHFbivi4xwXxhxY9XHDe2FHo6/Z7WWmtT7T5nBBp3I=
 github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
 github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
+github.com/lmittmann/tint v1.1.2 h1:2CQzrL6rslrsyjqLDwD11bZ5OpLBPU+g3G/r5LSfS8w=
+github.com/lmittmann/tint v1.1.2/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-sqlite3 v1.14.24 h1:tpSp2G2KyMnnQu99ngJ47EIkWVmliIizyZBfPrBWDRM=
@@ -208,6 +210,8 @@ github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8
 github.com/opencontainers/go-digest v1.0.0/go.mod h1:0JzlMkj0TRzQZfJkVvzbP0HBR3IKzErnv2BNG4W4MAM=
 github.com/opencontainers/image-spec v1.1.0 h1:8SG7/vwALn54lVB/0yZ/MMwhFrPYtpEHQb2IpWsCzug=
 github.com/opencontainers/image-spec v1.1.0/go.mod h1:W4s4sFTMaBeK1BQLXbG4AdM2szdn85PY75RI83NrTrM=
+github.com/orandin/slog-gorm v1.4.0 h1:FgA8hJufF9/jeNSYoEXmHPPBwET2gwlF3B85JdpsTUU=
+github.com/orandin/slog-gorm v1.4.0/go.mod h1:MoZ51+b7xE9lwGNPYEhxcUtRNrYzjdcKvA8QXQQGEPA=
 github.com/oschwald/maxminddb-golang/v2 v2.0.0-beta.2 h1:jG+FaCBv3h6GD5F+oenTfe3+0NmX8sCKjni5k3A5Dek=
 github.com/oschwald/maxminddb-golang/v2 v2.0.0-beta.2/go.mod h1:rHaQJ5SjfCdL4sqCKa3FhklRcaXga2/qyvmQuA+ZJ6M=
 github.com/pelletier/go-toml/v2 v2.2.3 h1:YmeHyLY8mFWbdkNWwpr+qIL2bEqT0o95WSdkNHvL12M=
@@ -231,6 +235,8 @@ github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzG
 github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/samber/slog-gin v1.15.1 h1:jsnfr+S5HQPlz9pFPA3tOmKW7wN/znyZiE6hncucrTM=
+github.com/samber/slog-gin v1.15.1/go.mod h1:mPAEinK/g2jPLauuWO11m3Q0Ca7aG4k9XjXjXY8IhMQ=
 github.com/segmentio/asm v1.2.0 h1:9BQrFxC+YOHJlTlHGkTrFWf59nbL3XnCoFLTwDCI7ys=
 github.com/segmentio/asm v1.2.0/go.mod h1:BqMnlJP91P8d+4ibuonYZw9mfnzI9HfxselHZr5aAcs=
 github.com/spf13/cobra v1.9.1 h1:CXSaggrXdbHK9CF+8ywj8Amf7PBRmPCOJugH954Nnlo=
@@ -260,6 +266,8 @@ github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcY
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
 go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
+go.opentelemetry.io/contrib/bridges/otelslog v0.12.0 h1:lFM7SZo8Ce01RzRfnUFQZEYeWRf/MtOA3A5MobOqk2g=
+go.opentelemetry.io/contrib/bridges/otelslog v0.12.0/go.mod h1:Dw05mhFtrKAYu72Tkb3YBYeQpRUJ4quDgo2DQw3No5A=
 go.opentelemetry.io/contrib/bridges/prometheus v0.59.0 h1:HY2hJ7yn3KuEBBBsKxvF3ViSmzLwsgeNvD+0utRMgzc=
 go.opentelemetry.io/contrib/bridges/prometheus v0.59.0/go.mod h1:H4H7vs8766kwFnOZVEGMJFVF+phpBSmTckvvNRdJeDI=
 go.opentelemetry.io/contrib/exporters/autoexport v0.59.0 h1:dKhAFwh7SSoOw+gwMtSv+XLkUGTFAwAGMT3X3XSE4FA=
@@ -268,8 +276,8 @@ go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin v0.
 go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin v0.60.0/go.mod h1:ZvRTVaYYGypytG0zRp2A60lpj//cMq3ZnxYdZaljVBM=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.54.0 h1:TT4fX+nBOA/+LUkobKGW1ydGcn+G3vRw9+g5HwCphpk=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.54.0/go.mod h1:L7UH0GbB0p47T4Rri3uHjbpCFYrVrwc1I25QhNPiGK8=
-go.opentelemetry.io/otel v1.35.0 h1:xKWKPxrxB6OtMCbmMY021CqC45J+3Onta9MqjhnusiQ=
+go.opentelemetry.io/otel v1.37.0 h1:9zhNfelUvx0KBfu/gb+ZgeAfAgtWrfHJZcAqFC228wQ=
-go.opentelemetry.io/otel v1.35.0/go.mod h1:UEqy8Zp11hpkUrL73gSlELM0DupHoiq72dR+Zqel/+Y=
+go.opentelemetry.io/otel v1.37.0/go.mod h1:ehE/umFRLnuLa/vSccNq9oS1ErUlkkK71gMcN34UG8I=
 go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.10.0 h1:5dTKu4I5Dn4P2hxyW3l3jTaZx9ACgg0ECos1eAVrheY=
 go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.10.0/go.mod h1:P5HcUI8obLrCCmM3sbVBohZFH34iszk/+CPWuakZWL8=
 go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.10.0 h1:q/heq5Zh8xV1+7GoMGJpTxM2Lhq5+bFxB29tshuRuw0=
@@ -292,18 +300,18 @@ go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.35.0 h1:PB3Zrjs1sG1GBX
 go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.35.0/go.mod h1:U2R3XyVPzn0WX7wOIypPuptulsMcPDPs/oiSVOMVnHY=
 go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.35.0 h1:T0Ec2E+3YZf5bgTNQVet8iTDW7oIk03tXHq+wkwIDnE=
 go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.35.0/go.mod h1:30v2gqH+vYGJsesLWFov8u47EpYTcIQcBjKpI6pJThg=
-go.opentelemetry.io/otel/log v0.10.0 h1:1CXmspaRITvFcjA4kyVszuG4HjA61fPDxMb7q3BuyF0=
+go.opentelemetry.io/otel/log v0.13.0 h1:yoxRoIZcohB6Xf0lNv9QIyCzQvrtGZklVbdCoyb7dls=
-go.opentelemetry.io/otel/log v0.10.0/go.mod h1:PbVdm9bXKku/gL0oFfUF4wwsQsOPlpo4VEqjvxih+FM=
+go.opentelemetry.io/otel/log v0.13.0/go.mod h1:INKfG4k1O9CL25BaM1qLe0zIedOpvlS5Z7XgSbmN83E=
-go.opentelemetry.io/otel/metric v1.35.0 h1:0znxYu2SNyuMSQT4Y9WDWej0VpcsxkuklLa4/siN90M=
+go.opentelemetry.io/otel/metric v1.37.0 h1:mvwbQS5m0tbmqML4NqK+e3aDiO02vsf/WgbsdpcPoZE=
-go.opentelemetry.io/otel/metric v1.35.0/go.mod h1:nKVFgxBZ2fReX6IlyW28MgZojkoAkJGaE8CpgeAU3oE=
+go.opentelemetry.io/otel/metric v1.37.0/go.mod h1:04wGrZurHYKOc+RKeye86GwKiTb9FKm1WHtO+4EVr2E=
 go.opentelemetry.io/otel/sdk v1.35.0 h1:iPctf8iprVySXSKJffSS79eOjl9pvxV9ZqOWT0QejKY=
 go.opentelemetry.io/otel/sdk v1.35.0/go.mod h1:+ga1bZliga3DxJ3CQGg3updiaAJoNECOgJREo9KHGQg=
 go.opentelemetry.io/otel/sdk/log v0.10.0 h1:lR4teQGWfeDVGoute6l0Ou+RpFqQ9vaPdrNJlST0bvw=
 go.opentelemetry.io/otel/sdk/log v0.10.0/go.mod h1:A+V1UTWREhWAittaQEG4bYm4gAZa6xnvVu+xKrIRkzo=
 go.opentelemetry.io/otel/sdk/metric v1.35.0 h1:1RriWBmCKgkeHEhM7a2uMjMUfP7MsOF5JpUCaEqEI9o=
 go.opentelemetry.io/otel/sdk/metric v1.35.0/go.mod h1:is6XYCUMpcKi+ZsOvfluY5YstFnhW0BidkR+gL+qN+w=
-go.opentelemetry.io/otel/trace v1.35.0 h1:dPpEfJu1sDIqruz7BHFG3c7528f6ddfSWfFDVt/xgMs=
+go.opentelemetry.io/otel/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
-go.opentelemetry.io/otel/trace v1.35.0/go.mod h1:WUk7DtFp1Aw2MkvqGdwiXYDZZNvA/1J8o6xRXLrIkyc=
+go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
 go.opentelemetry.io/proto/otlp v1.5.0 h1:xJvq7gMzB31/d406fB8U5CBdyQGw4P399D1aQWU/3i4=
 go.opentelemetry.io/proto/otlp v1.5.0/go.mod h1:keN8WnHxOy8PG0rQZjJJ5A2ebUoafqWp0eVQ4yIXvJ4=
 go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=

backend/internal/bootstrap/application_images_bootstrap.go

@@ -1,7 +1,7 @@
 package bootstrap
 
 import (
-	"log"
+	"fmt"
 	"os"
 	"path"
 	"strings"
@@ -12,17 +12,17 @@ import (
 )
 
 // initApplicationImages copies the images from the images directory to the application-images directory
-func initApplicationImages() {
+func initApplicationImages() error {
 	dirPath := common.EnvConfig.UploadPath + "/application-images"
 
 	sourceFiles, err := resources.FS.ReadDir("images")
 	if err != nil && !os.IsNotExist(err) {
-		log.Fatalf("Error reading directory: %v", err)
+		return fmt.Errorf("failed to read directory: %w", err)
 	}
 
 	destinationFiles, err := os.ReadDir(dirPath)
 	if err != nil && !os.IsNotExist(err) {
-		log.Fatalf("Error reading directory: %v", err)
+		return fmt.Errorf("failed to read directory: %w", err)
 	}
 
 	// Copy images from the images directory to the application-images directory if they don't already exist
@@ -35,9 +35,11 @@ func initApplicationImages() {
 
 		err := utils.CopyEmbeddedFileToDisk(srcFilePath, destFilePath)
 		if err != nil {
-			log.Fatalf("Error copying file: %v", err)
+			return fmt.Errorf("failed to copy file: %w", err)
 		}
 	}
+
+	return nil
 }
 
 func imageAlreadyExists(fileName string, destinationFiles []os.DirEntry) bool {

backend/internal/bootstrap/bootstrap.go

@@ -3,7 +3,7 @@ package bootstrap
 import (
 	"context"
 	"fmt"
-	"log"
+	"log/slog"
 	"time"
 
 	_ "github.com/golang-migrate/migrate/v4/source/file"
@@ -14,13 +14,17 @@ import (
 )
 
 func Bootstrap(ctx context.Context) error {
-	initApplicationImages()
+	// Initialize the observability stack, including the logger, distributed tracing, and metrics
-
+	shutdownFns, httpClient, err := initObservability(ctx, common.EnvConfig.MetricsEnabled, common.EnvConfig.TracingEnabled)
-	// Initialize the tracer and metrics exporter
-	shutdownFns, httpClient, err := initOtel(ctx, common.EnvConfig.MetricsEnabled, common.EnvConfig.TracingEnabled)
 	if err != nil {
 		return fmt.Errorf("failed to initialize OpenTelemetry: %w", err)
 	}
+	slog.InfoContext(ctx, "Pocket ID is starting")
+
+	err = initApplicationImages()
+	if err != nil {
+		return fmt.Errorf("failed to initialize application images: %w", err)
+	}
 
 	// Connect to the database
 	db := NewDatabase()
@@ -62,7 +66,7 @@ func Bootstrap(ctx context.Context) error {
 		NewServiceRunner(shutdownFns...).
 		Run(shutdownCtx) //nolint:contextcheck
 	if err != nil {
-		log.Printf("Error shutting down services: %v", err)
+		slog.Error("Error shutting down services", slog.Any("error", err))
 	}
 
 	return nil

backend/internal/bootstrap/db_bootstrap.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"fmt"
 	"log"
+	"log/slog"
 	"net/url"
-	"os"
 	"strings"
 	"time"
 
@@ -15,9 +15,10 @@ import (
 	postgresMigrate "github.com/golang-migrate/migrate/v4/database/postgres"
 	sqliteMigrate "github.com/golang-migrate/migrate/v4/database/sqlite3"
 	"github.com/golang-migrate/migrate/v4/source/iofs"
+	slogGorm "github.com/orandin/slog-gorm"
 	"gorm.io/driver/postgres"
 	"gorm.io/gorm"
-	"gorm.io/gorm/logger"
+	gormLogger "gorm.io/gorm/logger"
 
 	"github.com/pocket-id/pocket-id/backend/internal/common"
 	sqliteutil "github.com/pocket-id/pocket-id/backend/internal/utils/sqlite"
@@ -107,13 +108,13 @@ func connectDatabase() (db *gorm.DB, err error) {
 	for i := 1; i <= 3; i++ {
 		db, err = gorm.Open(dialector, &gorm.Config{
 			TranslateError: true,
-			Logger:         getLogger(),
+			Logger:         getGormLogger(),
 		})
 		if err == nil {
 			return db, nil
 		}
 
-		log.Printf("Attempt %d: Failed to initialize database. Retrying...", i)
+		slog.Info("Failed to initialize database", slog.Int("attempt", i))
 		time.Sleep(3 * time.Second)
 	}
 
@@ -164,24 +165,25 @@ func parseSqliteConnectionString(connString string) (string, error) {
 	return connStringUrl.String(), nil
 }
 
-func getLogger() logger.Interface {
+func getGormLogger() gormLogger.Interface {
-	isProduction := common.EnvConfig.AppEnv == "production"
+	loggerOpts := make([]slogGorm.Option, 0, 5)
+	loggerOpts = append(loggerOpts,
+		slogGorm.WithSlowThreshold(200*time.Millisecond),
+		slogGorm.WithErrorField("error"),
+	)
 
-	var logLevel logger.LogLevel
+	if common.EnvConfig.AppEnv == "production" {
-	if isProduction {
+		loggerOpts = append(loggerOpts,
-		logLevel = logger.Error
+			slogGorm.SetLogLevel(slogGorm.DefaultLogType, slog.LevelWarn),
+			slogGorm.WithIgnoreTrace(),
+		)
 	} else {
-		logLevel = logger.Info
+		loggerOpts = append(loggerOpts,
+			slogGorm.SetLogLevel(slogGorm.DefaultLogType, slog.LevelDebug),
+			slogGorm.WithRecordNotFoundError(),
+			slogGorm.WithTraceAll(),
+		)
 	}
 
-	return logger.New(
+	return slogGorm.New(loggerOpts...)
-		log.New(os.Stdout, "\r\n", log.LstdFlags),
-		logger.Config{
-			SlowThreshold:             200 * time.Millisecond,
-			LogLevel:                  logLevel,
-			IgnoreRecordNotFoundError: isProduction,
-			ParameterizedQueries:      isProduction,
-			Colorful:                  !isProduction,
-		},
-	)
 }

backend/internal/bootstrap/observability_boostrap.go

@@ -0,0 +1,210 @@
+package bootstrap
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/lmittmann/tint"
+	"github.com/mattn/go-isatty"
+	"go.opentelemetry.io/contrib/bridges/otelslog"
+	"go.opentelemetry.io/contrib/exporters/autoexport"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+	"go.opentelemetry.io/otel"
+	globallog "go.opentelemetry.io/otel/log/global"
+	metricnoop "go.opentelemetry.io/otel/metric/noop"
+	"go.opentelemetry.io/otel/propagation"
+	sdklog "go.opentelemetry.io/otel/sdk/log"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.30.0"
+	tracenoop "go.opentelemetry.io/otel/trace/noop"
+
+	"github.com/pocket-id/pocket-id/backend/internal/common"
+	"github.com/pocket-id/pocket-id/backend/internal/utils"
+)
+
+func defaultResource() (*resource.Resource, error) {
+	return resource.Merge(
+		resource.Default(),
+		resource.NewSchemaless(
+			semconv.ServiceName(common.Name),
+			semconv.ServiceVersion(common.Version),
+		),
+	)
+}
+
+func initObservability(ctx context.Context, metrics, traces bool) (shutdownFns []utils.Service, httpClient *http.Client, err error) {
+	resource, err := defaultResource()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to create OpenTelemetry resource: %w", err)
+	}
+
+	shutdownFns = make([]utils.Service, 0, 2)
+
+	httpClient = &http.Client{}
+	defaultTransport, ok := http.DefaultTransport.(*http.Transport)
+	if !ok {
+		// Indicates a development-time error
+		panic("Default transport is not of type *http.Transport")
+	}
+	httpClient.Transport = defaultTransport.Clone()
+
+	// Logging
+	err = initOtelLogging(ctx, resource)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Tracing
+	tracingShutdownFn, err := initOtelTracing(ctx, traces, resource, httpClient)
+	if err != nil {
+		return nil, nil, err
+	} else if tracingShutdownFn != nil {
+		shutdownFns = append(shutdownFns, tracingShutdownFn)
+	}
+
+	// Metrics
+	metricsShutdownFn, err := initOtelMetrics(ctx, metrics, resource)
+	if err != nil {
+		return nil, nil, err
+	} else if metricsShutdownFn != nil {
+		shutdownFns = append(shutdownFns, metricsShutdownFn)
+	}
+
+	return shutdownFns, httpClient, nil
+}
+
+func initOtelLogging(ctx context.Context, resource *resource.Resource) error {
+	// If the env var OTEL_LOGS_EXPORTER is empty, we set it to "none", for autoexport to work
+	if os.Getenv("OTEL_LOGS_EXPORTER") == "" {
+		os.Setenv("OTEL_LOGS_EXPORTER", "none")
+	}
+	exp, err := autoexport.NewLogExporter(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to initialize OpenTelemetry log exporter: %w", err)
+	}
+
+	level := slog.LevelDebug
+	if common.EnvConfig.AppEnv == "production" {
+		level = slog.LevelInfo
+	}
+
+	// Create the handler
+	var handler slog.Handler
+	switch {
+	case common.EnvConfig.LogJSON:
+		// Log as JSON if configured
+		handler = slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+			Level: level,
+		})
+	case isatty.IsTerminal(os.Stdout.Fd()):
+		// Enable colors if we have a TTY
+		handler = tint.NewHandler(os.Stdout, &tint.Options{
+			TimeFormat: time.StampMilli,
+			Level:      level,
+		})
+	default:
+		handler = slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+			Level: level,
+		})
+	}
+
+	// Create the logger provider
+	provider := sdklog.NewLoggerProvider(
+		sdklog.WithProcessor(
+			sdklog.NewBatchProcessor(exp),
+		),
+		sdklog.WithResource(resource),
+	)
+
+	// Set the logger provider globally
+	globallog.SetLoggerProvider(provider)
+
+	// Wrap the handler in a "fanout" one
+	handler = utils.LogFanoutHandler{
+		handler,
+		otelslog.NewHandler(common.Name, otelslog.WithLoggerProvider(provider)),
+	}
+
+	// Set the default slog to send logs to OTel and add the app name
+	log := slog.New(handler).
+		With(slog.String("app", common.Name)).
+		With(slog.String("version", common.Version))
+	slog.SetDefault(log)
+
+	return nil
+}
+
+func initOtelTracing(ctx context.Context, traces bool, resource *resource.Resource, httpClient *http.Client) (shutdownFn utils.Service, err error) {
+	if !traces {
+		otel.SetTracerProvider(tracenoop.NewTracerProvider())
+		return nil, nil
+	}
+
+	tr, err := autoexport.NewSpanExporter(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to initialize OpenTelemetry span exporter: %w", err)
+	}
+	tp := sdktrace.NewTracerProvider(
+		sdktrace.WithResource(resource),
+		sdktrace.WithBatcher(tr),
+	)
+
+	otel.SetTracerProvider(tp)
+	otel.SetTextMapPropagator(
+		propagation.NewCompositeTextMapPropagator(
+			propagation.TraceContext{},
+			propagation.Baggage{},
+		),
+	)
+
+	shutdownFn = func(shutdownCtx context.Context) error { //nolint:contextcheck
+		tpCtx, tpCancel := context.WithTimeout(shutdownCtx, 10*time.Second)
+		defer tpCancel()
+		shutdownErr := tp.Shutdown(tpCtx)
+		if shutdownErr != nil {
+			return fmt.Errorf("failed to gracefully shut down traces exporter: %w", shutdownErr)
+		}
+		return nil
+	}
+
+	// Add tracing to the HTTP client
+	httpClient.Transport = otelhttp.NewTransport(httpClient.Transport)
+
+	return shutdownFn, nil
+}
+
+func initOtelMetrics(ctx context.Context, metrics bool, resource *resource.Resource) (shutdownFn utils.Service, err error) {
+	if !metrics {
+		otel.SetMeterProvider(metricnoop.NewMeterProvider())
+		return nil, nil
+	}
+
+	mr, err := autoexport.NewMetricReader(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to initialize OpenTelemetry metric reader: %w", err)
+	}
+
+	mp := metric.NewMeterProvider(
+		metric.WithResource(resource),
+		metric.WithReader(mr),
+	)
+	otel.SetMeterProvider(mp)
+
+	shutdownFn = func(shutdownCtx context.Context) error { //nolint:contextcheck
+		mpCtx, mpCancel := context.WithTimeout(shutdownCtx, 10*time.Second)
+		defer mpCancel()
+		shutdownErr := mp.Shutdown(mpCtx)
+		if shutdownErr != nil {
+			return fmt.Errorf("failed to gracefully shut down metrics exporter: %w", shutdownErr)
+		}
+		return nil
+	}
+
+	return shutdownFn, nil
+}

backend/internal/bootstrap/otel_boostrap.go

@@ -1,107 +0,0 @@
-package bootstrap
-
-import (
-	"context"
-	"fmt"
-	"net/http"
-	"time"
-
-	"github.com/pocket-id/pocket-id/backend/internal/common"
-	"github.com/pocket-id/pocket-id/backend/internal/utils"
-	"go.opentelemetry.io/contrib/exporters/autoexport"
-	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
-	"go.opentelemetry.io/otel"
-	metricnoop "go.opentelemetry.io/otel/metric/noop"
-	"go.opentelemetry.io/otel/propagation"
-	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/resource"
-	sdktrace "go.opentelemetry.io/otel/sdk/trace"
-	semconv "go.opentelemetry.io/otel/semconv/v1.30.0"
-	tracenoop "go.opentelemetry.io/otel/trace/noop"
-)
-
-func defaultResource() (*resource.Resource, error) {
-	return resource.Merge(
-		resource.Default(),
-		resource.NewSchemaless(
-			semconv.ServiceName("pocket-id-backend"),
-			semconv.ServiceVersion(common.Version),
-		),
-	)
-}
-
-func initOtel(ctx context.Context, metrics, traces bool) (shutdownFns []utils.Service, httpClient *http.Client, err error) {
-	resource, err := defaultResource()
-	if err != nil {
-		return nil, nil, fmt.Errorf("failed to create OpenTelemetry resource: %w", err)
-	}
-
-	shutdownFns = make([]utils.Service, 0, 2)
-
-	httpClient = &http.Client{}
-	defaultTransport, ok := http.DefaultTransport.(*http.Transport)
-	if !ok {
-		// Indicates a development-time error
-		panic("Default transport is not of type *http.Transport")
-	}
-	httpClient.Transport = defaultTransport.Clone()
-
-	if traces {
-		tr, err := autoexport.NewSpanExporter(ctx)
-		if err != nil {
-			return nil, nil, fmt.Errorf("failed to initialize OpenTelemetry span exporter: %w", err)
-		}
-		tp := sdktrace.NewTracerProvider(
-			sdktrace.WithResource(resource),
-			sdktrace.WithBatcher(tr),
-		)
-
-		otel.SetTracerProvider(tp)
-		otel.SetTextMapPropagator(
-			propagation.NewCompositeTextMapPropagator(
-				propagation.TraceContext{},
-				propagation.Baggage{},
-			),
-		)
-
-		shutdownFns = append(shutdownFns, func(shutdownCtx context.Context) error { //nolint:contextcheck
-			tpCtx, tpCancel := context.WithTimeout(shutdownCtx, 10*time.Second)
-			defer tpCancel()
-			shutdownErr := tp.Shutdown(tpCtx)
-			if shutdownErr != nil {
-				return fmt.Errorf("failed to gracefully shut down traces exporter: %w", shutdownErr)
-			}
-			return nil
-		})
-
-		httpClient.Transport = otelhttp.NewTransport(httpClient.Transport)
-	} else {
-		otel.SetTracerProvider(tracenoop.NewTracerProvider())
-	}
-
-	if metrics {
-		mr, err := autoexport.NewMetricReader(ctx)
-		if err != nil {
-			return nil, nil, fmt.Errorf("failed to initialize OpenTelemetry metric reader: %w", err)
-		}
-		mp := metric.NewMeterProvider(
-			metric.WithResource(resource),
-			metric.WithReader(mr),
-		)
-
-		otel.SetMeterProvider(mp)
-		shutdownFns = append(shutdownFns, func(shutdownCtx context.Context) error { //nolint:contextcheck
-			mpCtx, mpCancel := context.WithTimeout(shutdownCtx, 10*time.Second)
-			defer mpCancel()
-			shutdownErr := mp.Shutdown(mpCtx)
-			if shutdownErr != nil {
-				return fmt.Errorf("failed to gracefully shut down metrics exporter: %w", shutdownErr)
-			}
-			return nil
-		})
-	} else {
-		otel.SetMeterProvider(metricnoop.NewMeterProvider())
-	}
-
-	return shutdownFns, httpClient, nil
-}

backend/internal/bootstrap/router_bootstrap.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"log"
+	"log/slog"
 	"net"
 	"net/http"
 	"os"
@@ -12,13 +12,13 @@ import (
 	"strings"
 	"time"
 
-	"github.com/pocket-id/pocket-id/backend/frontend"
-
 	"github.com/gin-gonic/gin"
+	sloggin "github.com/samber/slog-gin"
 	"go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"
 	"golang.org/x/time/rate"
 	"gorm.io/gorm"
 
+	"github.com/pocket-id/pocket-id/backend/frontend"
 	"github.com/pocket-id/pocket-id/backend/internal/common"
 	"github.com/pocket-id/pocket-id/backend/internal/controller"
 	"github.com/pocket-id/pocket-id/backend/internal/middleware"
@@ -32,7 +32,8 @@ var registerTestControllers []func(apiGroup *gin.RouterGroup, db *gorm.DB, svc *
 func initRouter(db *gorm.DB, svc *services) utils.Service {
 	runner, err := initRouterInternal(db, svc)
 	if err != nil {
-		log.Fatalf("failed to init router: %v", err)
+		slog.Error("Failed to init router", "error", err)
+		os.Exit(1)
 	}
 	return runner
 }
@@ -60,21 +61,25 @@ func initRouterInternal(db *gorm.DB, svc *services) (utils.Service, error) {
 	}
 
 	r := gin.New()
-	r.Use(gin.LoggerWithConfig(gin.LoggerConfig{Skip: func(c *gin.Context) bool {
+	r.Use(sloggin.NewWithConfig(slog.Default(), sloggin.Config{
-		for _, prefix := range loggerSkipPathsPrefix {
+		Filters: []sloggin.Filter{
-			if strings.HasPrefix(c.Request.Method+" "+c.Request.URL.String(), prefix) {
+			func(c *gin.Context) bool {
+				for _, prefix := range loggerSkipPathsPrefix {
+					if strings.HasPrefix(c.Request.Method+" "+c.Request.URL.String(), prefix) {
+						return false
+					}
+				}
 				return true
-			}
+			},
-		}
+		},
-		return false
+	}))
-	}}))
 
 	if !common.EnvConfig.TrustProxy {
 		_ = r.SetTrustedProxies(nil)
 	}
 
 	if common.EnvConfig.TracingEnabled {
-		r.Use(otelgin.Middleware("pocket-id-backend"))
+		r.Use(otelgin.Middleware(common.Name))
 	}
 
 	rateLimitMiddleware := middleware.NewRateLimitMiddleware().Add(rate.Every(time.Second), 60)
@@ -85,7 +90,7 @@ func initRouterInternal(db *gorm.DB, svc *services) (utils.Service, error) {
 
 	err := frontend.RegisterFrontend(r)
 	if errors.Is(err, frontend.ErrFrontendNotIncluded) {
-		log.Println("Frontend is not included in the build. Skipping frontend registration.")
+		slog.Warn("Frontend is not included in the build. Skipping frontend registration.")
 	} else if err != nil {
 		return nil, fmt.Errorf("failed to register frontend: %w", err)
 	}
@@ -154,7 +159,7 @@ func initRouterInternal(db *gorm.DB, svc *services) (utils.Service, error) {
 
 	// Service runner function
 	runFn := func(ctx context.Context) error {
-		log.Printf("Server listening on %s", addr)
+		slog.Info("Server listening", slog.String("addr", addr))
 
 		// Start the server in a background goroutine
 		go func() {
@@ -163,7 +168,8 @@ func initRouterInternal(db *gorm.DB, svc *services) (utils.Service, error) {
 			// Next call blocks until the server is shut down
 			srvErr := srv.Serve(listener)
 			if srvErr != http.ErrServerClosed {
-				log.Fatalf("Error starting app server: %v", srvErr)
+				slog.Error("Error starting app server", "error", srvErr)
+				os.Exit(1)
 			}
 		}()
 
@@ -171,7 +177,7 @@ func initRouterInternal(db *gorm.DB, svc *services) (utils.Service, error) {
 		err = systemd.SdNotifyReady()
 		if err != nil {
 			// Log the error only
-			log.Printf("[WARN] Unable to notify systemd that the service is ready: %v", err)
+			slog.Warn("Unable to notify systemd that the service is ready", "error", err)
 		}
 
 		// Block until the context is canceled
@@ -184,7 +190,7 @@ func initRouterInternal(db *gorm.DB, svc *services) (utils.Service, error) {
 		shutdownCancel()
 		if shutdownErr != nil {
 			// Log the error only (could be context canceled)
-			log.Printf("[WARN] App server shutdown error: %v", shutdownErr)
+			slog.Warn("App server shutdown error", "error", shutdownErr)
 		}
 
 		return nil

backend/internal/bootstrap/services_bootstrap.go

@@ -38,7 +38,11 @@ func initServices(ctx context.Context, db *gorm.DB, httpClient *http.Client) (sv
 
 	svc.geoLiteService = service.NewGeoLiteService(httpClient)
 	svc.auditLogService = service.NewAuditLogService(db, svc.appConfigService, svc.emailService, svc.geoLiteService)
-	svc.jwtService = service.NewJwtService(db, svc.appConfigService)
+	svc.jwtService, err = service.NewJwtService(db, svc.appConfigService)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create JWT service: %w", err)
+	}
+
 	svc.userService = service.NewUserService(db, svc.jwtService, svc.auditLogService, svc.emailService, svc.appConfigService)
 	svc.customClaimService = service.NewCustomClaimService(db)
 

backend/internal/common/env_config.go

@@ -47,6 +47,7 @@ type EnvConfigSchema struct {
 	UiConfigDisabled   bool       `env:"UI_CONFIG_DISABLED"`
 	MetricsEnabled     bool       `env:"METRICS_ENABLED"`
 	TracingEnabled     bool       `env:"TRACING_ENABLED"`
+	LogJSON            bool       `env:"LOG_JSON"`
 	TrustProxy         bool       `env:"TRUST_PROXY"`
 	AnalyticsDisabled  bool       `env:"ANALYTICS_DISABLED"`
 }

backend/internal/common/version.go

@@ -1,5 +1,8 @@
 package common
 
+// Name is the name of the application
+const Name = "pocket-id"
+
 // Version contains the Pocket ID version.
 //
 // It can be set at build time using -ldflags.

backend/internal/controller/oidc_controller.go

@@ -2,7 +2,7 @@ package controller
 
 import (
 	"errors"
-	"log"
+	"log/slog"
 	"net/http"
 	"net/url"
 	"strings"
@@ -257,7 +257,7 @@ func (oc *OidcController) EndSessionHandler(c *gin.Context) {
 	callbackURL, err := oc.oidcService.ValidateEndSession(c.Request.Context(), input, c.GetString("userID"))
 	if err != nil {
 		// If the validation fails, the user has to confirm the logout manually and doesn't get redirected
-		log.Printf("Error getting logout callback URL, the user has to confirm the logout manually: %v", err)
+		slog.WarnContext(c.Request.Context(), "Error getting logout callback URL, the user has to confirm the logout manually", "error", err)
 		c.Redirect(http.StatusFound, common.EnvConfig.AppURL+"/logout")
 		return
 	}

backend/internal/service/app_config_service.go

@@ -14,7 +14,6 @@ import (
 	"time"
 
 	"github.com/hashicorp/go-uuid"
-
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
 

backend/internal/service/audit_log_service.go

@@ -3,7 +3,6 @@ package service
 import (
 	"context"
 	"fmt"
-	"log"
 	"log/slog"
 
 	userAgentParser "github.com/mileusna/useragent"
@@ -11,6 +10,7 @@ import (
 	"github.com/pocket-id/pocket-id/backend/internal/model"
 	"github.com/pocket-id/pocket-id/backend/internal/utils"
 	"github.com/pocket-id/pocket-id/backend/internal/utils/email"
+	"go.opentelemetry.io/otel/trace"
 	"gorm.io/gorm"
 )
 
@@ -82,7 +82,7 @@ func (s *AuditLogService) CreateNewSignInWithEmail(ctx context.Context, ipAddres
 	}
 	err := stmt.Count(&count).Error
 	if err != nil {
-		log.Printf("Failed to count audit logs: %v", err)
+		slog.ErrorContext(ctx, "Failed to count audit logs", slog.Any("error", err))
 		return createdAuditLog
 	}
 
@@ -91,7 +91,8 @@ func (s *AuditLogService) CreateNewSignInWithEmail(ctx context.Context, ipAddres
 		// We use a background context here as this is running in a goroutine
 		//nolint:contextcheck
 		go func() {
-			innerCtx := context.Background()
+			span := trace.SpanFromContext(ctx)
+			innerCtx := trace.ContextWithSpan(context.Background(), span)
 
 			// Note we don't use the transaction here because this is running in background
 			var user model.User
@@ -101,7 +102,8 @@ func (s *AuditLogService) CreateNewSignInWithEmail(ctx context.Context, ipAddres
 				First(&user).
 				Error
 			if innerErr != nil {
-				log.Printf("Failed to load user: %v", innerErr)
+				slog.ErrorContext(innerCtx, "Failed to load user from database to send notification email", slog.Any("error", innerErr))
+				return
 			}
 
 			innerErr = SendEmail(innerCtx, s.emailService, email.Address{
@@ -115,7 +117,8 @@ func (s *AuditLogService) CreateNewSignInWithEmail(ctx context.Context, ipAddres
 				DateTime:  createdAuditLog.CreatedAt.UTC(),
 			})
 			if innerErr != nil {
-				log.Printf("Failed to send email to '%s': %v", user.Email, innerErr)
+				slog.ErrorContext(innerCtx, "Failed to send notification email", slog.Any("error", innerErr), slog.String("address", user.Email))
+				return
 			}
 		}()
 	}

backend/internal/service/geolite_service.go

@@ -7,7 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"log"
+	"log/slog"
 	"net"
 	"net/http"
 	"net/netip"
@@ -52,13 +52,13 @@ func NewGeoLiteService(httpClient *http.Client) *GeoLiteService {
 
 	if common.EnvConfig.MaxMindLicenseKey == "" && common.EnvConfig.GeoLiteDBUrl == common.MaxMindGeoLiteCityUrl {
 		// Warn the user, and disable the periodic updater
-		log.Println("MAXMIND_LICENSE_KEY environment variable is empty. The GeoLite2 City database won't be updated.")
+		slog.Warn("MAXMIND_LICENSE_KEY environment variable is empty: the GeoLite2 City database won't be updated")
 		service.disableUpdater = true
 	}
 
 	// Initialize IPv6 local ranges
 	if err := service.initializeIPv6LocalRanges(); err != nil {
-		log.Printf("Warning: Failed to initialize IPv6 local ranges: %v", err)
+		slog.Warn("Failed to initialize IPv6 local ranges", slog.Any("error", err))
 	}
 
 	return service
@@ -96,7 +96,7 @@ func (s *GeoLiteService) initializeIPv6LocalRanges() error {
 	s.localIPv6Ranges = localRanges
 
 	if len(localRanges) > 0 {
-		log.Printf("Initialized %d IPv6 local ranges", len(localRanges))
+		slog.Info("Initialized IPv6 local ranges", slog.Int("count", len(localRanges)))
 	}
 	return nil
 }
@@ -186,11 +186,11 @@ func (s *GeoLiteService) GetLocationByIP(ipAddress string) (country, city string
 // UpdateDatabase checks the age of the database and updates it if it's older than 14 days.
 func (s *GeoLiteService) UpdateDatabase(parentCtx context.Context) error {
 	if s.isDatabaseUpToDate() {
-		log.Println("GeoLite2 City database is up-to-date")
+		slog.Info("GeoLite2 City database is up-to-date")
 		return nil
 	}
 
-	log.Println("Updating GeoLite2 City database")
+	slog.Info("Updating GeoLite2 City database")
 	downloadUrl := fmt.Sprintf(common.EnvConfig.GeoLiteDBUrl, common.EnvConfig.MaxMindLicenseKey)
 
 	ctx, cancel := context.WithTimeout(parentCtx, 10*time.Minute)
@@ -217,7 +217,7 @@ func (s *GeoLiteService) UpdateDatabase(parentCtx context.Context) error {
 		return fmt.Errorf("failed to extract database: %w", err)
 	}
 
-	log.Println("GeoLite2 City database successfully updated.")
+	slog.Info("GeoLite2 City database successfully updated.")
 	return nil
 }
 

backend/internal/service/jwt_service.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"log"
 	"time"
 
 	"github.com/lestrrat-go/jwx/v3/jwa"
@@ -64,16 +63,16 @@ type JwtService struct {
 	jwksEncoded      []byte
 }
 
-func NewJwtService(db *gorm.DB, appConfigService *AppConfigService) *JwtService {
+func NewJwtService(db *gorm.DB, appConfigService *AppConfigService) (*JwtService, error) {
 	service := &JwtService{}
 
 	// Ensure keys are generated or loaded
 	err := service.init(db, appConfigService, &common.EnvConfig)
 	if err != nil {
-		log.Fatalf("Failed to initialize jwt service: %v", err)
+		return nil, err
 	}
 
-	return service
+	return service, nil
 }
 
 func (s *JwtService) init(db *gorm.DB, appConfigService *AppConfigService, envConfig *common.EnvConfigSchema) (err error) {

backend/internal/service/ldap_service.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"log/slog"
 	"net/http"
 	"net/url"
 	"strings"
@@ -130,7 +131,7 @@ func (s *LdapService) SyncGroups(ctx context.Context, tx *gorm.DB, client *ldap.
 
 		// Skip groups without a valid LDAP ID
 		if ldapId == "" {
-			log.Printf("Skipping LDAP group without a valid unique identifier (attribute: %s)", dbConfig.LdapAttributeGroupUniqueIdentifier.Value)
+			slog.Warn("Skipping LDAP group without a valid unique identifier", slog.String("attribute", dbConfig.LdapAttributeGroupUniqueIdentifier.Value))
 			continue
 		}
 
@@ -250,7 +251,7 @@ func (s *LdapService) SyncGroups(ctx context.Context, tx *gorm.DB, client *ldap.
 			return fmt.Errorf("failed to delete group '%s': %w", group.Name, err)
 		}
 
-		log.Printf("Deleted group '%s'", group.Name)
+		slog.Info("Deleted group", slog.String("group", group.Name))
 	}
 
 	return nil
@@ -295,7 +296,7 @@ func (s *LdapService) SyncUsers(ctx context.Context, tx *gorm.DB, client *ldap.C
 
 		// Skip users without a valid LDAP ID
 		if ldapId == "" {
-			log.Printf("Skipping LDAP user without a valid unique identifier (attribute: %s)", dbConfig.LdapAttributeUserUniqueIdentifier.Value)
+			slog.Warn("Skipping LDAP user without a valid unique identifier", slog.String("attribute", dbConfig.LdapAttributeUserUniqueIdentifier.Value))
 			continue
 		}
 
@@ -350,7 +351,7 @@ func (s *LdapService) SyncUsers(ctx context.Context, tx *gorm.DB, client *ldap.C
 		if databaseUser.ID == "" {
 			_, err = s.userService.createUserInternal(ctx, newUser, true, tx)
 			if errors.Is(err, &common.AlreadyInUseError{}) {
-				log.Printf("Skipping creating LDAP user '%s': %v", newUser.Username, err)
+				slog.Warn("Skipping creating LDAP user", slog.String("username", newUser.Username), slog.Any("error", err))
 				continue
 			} else if err != nil {
 				return fmt.Errorf("error creating user '%s': %w", newUser.Username, err)
@@ -358,7 +359,7 @@ func (s *LdapService) SyncUsers(ctx context.Context, tx *gorm.DB, client *ldap.C
 		} else {
 			_, err = s.userService.updateUserInternal(ctx, databaseUser.ID, newUser, false, true, tx)
 			if errors.Is(err, &common.AlreadyInUseError{}) {
-				log.Printf("Skipping updating LDAP user '%s': %v", newUser.Username, err)
+				slog.Warn("Skipping updating LDAP user", slog.String("username", newUser.Username), slog.Any("error", err))
 				continue
 			} else if err != nil {
 				return fmt.Errorf("error updating user '%s': %w", newUser.Username, err)
@@ -371,7 +372,7 @@ func (s *LdapService) SyncUsers(ctx context.Context, tx *gorm.DB, client *ldap.C
 			err = s.saveProfilePicture(ctx, databaseUser.ID, pictureString)
 			if err != nil {
 				// This is not a fatal error
-				log.Printf("Error saving profile picture for user %s: %v", newUser.Username, err)
+				slog.Warn("Error saving profile picture for user", slog.String("username", newUser.Username), slog.Any("error", err))
 			}
 		}
 	}
@@ -400,7 +401,7 @@ func (s *LdapService) SyncUsers(ctx context.Context, tx *gorm.DB, client *ldap.C
 				return fmt.Errorf("failed to disable user %s: %w", user.Username, err)
 			}
 
-			log.Printf("Disabled user '%s'", user.Username)
+			slog.Info("Disabled user", slog.String("username", user.Username))
 		} else {
 			err = s.userService.deleteUserInternal(ctx, user.ID, true, tx)
 			target := &common.LdapUserUpdateError{}
@@ -410,7 +411,7 @@ func (s *LdapService) SyncUsers(ctx context.Context, tx *gorm.DB, client *ldap.C
 				return fmt.Errorf("failed to delete user %s: %w", user.Username, err)
 			}
 
-			log.Printf("Deleted user '%s'", user.Username)
+			slog.Info("Deleted user", slog.String("username", user.Username))
 		}
 	}
 

backend/internal/service/user_service.go

@@ -7,12 +7,14 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"log/slog"
 	"net/url"
 	"os"
 	"strings"
 	"time"
 
 	"github.com/google/uuid"
+	"go.opentelemetry.io/otel/trace"
 	"gorm.io/gorm"
 
 	"github.com/pocket-id/pocket-id/backend/internal/common"
@@ -393,7 +395,8 @@ func (s *UserService) requestOneTimeAccessEmailInternal(ctx context.Context, use
 	// We use a background context here as this is running in a goroutine
 	//nolint:contextcheck
 	go func() {
-		innerCtx := context.Background()
+		span := trace.SpanFromContext(ctx)
+		innerCtx := trace.ContextWithSpan(context.Background(), span)
 
 		link := common.EnvConfig.AppURL + "/lc"
 		linkWithCode := link + "/" + oneTimeAccessToken
@@ -414,7 +417,8 @@ func (s *UserService) requestOneTimeAccessEmailInternal(ctx context.Context, use
 			ExpirationString:  utils.DurationToString(time.Until(expiration).Round(time.Second)),
 		})
 		if errInternal != nil {
-			log.Printf("Failed to send email to '%s': %v\n", user.Email, errInternal)
+			slog.ErrorContext(innerCtx, "Failed to send one-time access token email", slog.Any("error", errInternal), slog.String("address", user.Email))
+			return
 		}
 	}()
 

backend/internal/utils/slogfanout.go

@@ -0,0 +1,85 @@
+package utils
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"slices"
+)
+
+// This file contains code adapted from https://github.com/samber/slog-multi
+// Source: https://github.com/samber/slog-multi/blob/ced84707f45ec9848138349ed58de178eedaa6f2/pipe.go
+// Copyright (C) 2023 Samuel Berthe
+// License: MIT (https://github.com/samber/slog-multi/blob/ced84707f45ec9848138349ed58de178eedaa6f2/LICENSE)
+
+// LogFanoutHandler is a slog.Handler that sends logs to multiple destinations
+type LogFanoutHandler []slog.Handler
+
+// Implements slog.Handler
+func (h LogFanoutHandler) Enabled(ctx context.Context, l slog.Level) bool {
+	for i := range h {
+		if h[i].Enabled(ctx, l) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Implements slog.Handler
+func (h LogFanoutHandler) Handle(ctx context.Context, r slog.Record) error {
+	errs := make([]error, 0)
+	for i := range h {
+		if h[i].Enabled(ctx, r.Level) {
+			err := try(func() error {
+				return h[i].Handle(ctx, r.Clone())
+			})
+			if err != nil {
+				errs = append(errs, err)
+			}
+		}
+	}
+
+	return errors.Join(errs...)
+}
+
+// Implements slog.Handler
+func (h LogFanoutHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	res := make(LogFanoutHandler, len(h))
+	for i, v := range h {
+		res[i] = v.WithAttrs(slices.Clone(attrs))
+	}
+	return res
+}
+
+// Implements slog.Handler
+func (h LogFanoutHandler) WithGroup(name string) slog.Handler {
+	// https://cs.opensource.google/go/x/exp/+/46b07846:slog/handler.go;l=247
+	if name == "" {
+		return h
+	}
+
+	res := make(LogFanoutHandler, len(h))
+	for i, v := range h {
+		res[i] = v.WithGroup(name)
+	}
+	return res
+}
+
+func try(callback func() error) (err error) {
+	defer func() {
+		r := recover()
+		if r != nil {
+			if e, ok := r.(error); ok {
+				err = e
+			} else {
+				err = fmt.Errorf("unexpected error: %+v", r)
+			}
+		}
+	}()
+
+	err = callback()
+
+	return
+}