Breaking change: Add `ScanSchedule`, allows interval and cron based configurations.

See https://pkg.go.dev/github.com/robfig/cron#hdr-CRON_Expression_Format for expression syntax.

`ScanInterval` will still work for the time being. The only situation it does not work is when you want to disable periodic scanning by setting `ScanInterval=0`. If you want to disable it, please set `ScanSchedule=""`

Closes #1085

cmd/root.go

@@ -56,12 +56,13 @@ func runNavidrome() {
 
 	g.Add(startServer())
 	g.Add(startSignaler())
+	g.Add(startScheduler())
 
-	interval := conf.Server.ScanInterval
-	if interval != 0 {
-		g.Add(startPeriodicScan(interval))
+	schedule := conf.Server.ScanSchedule
+	if schedule != "" {
+		go schedulePeriodicScan(schedule)
 	} else {
-		log.Warn("Periodic scan is DISABLED", "interval", interval)
+		log.Warn("Periodic scan is DISABLED", "schedule", schedule)
 	}
 
 	if err := g.Run(); err != nil {
@@ -115,22 +116,40 @@ func startSignaler() (func() error, func(err error)) {
 		}
 }
 
-func startPeriodicScan(interval time.Duration) (func() error, func(err error)) {
-	log.Info("Starting scanner", "interval", interval.String())
+func schedulePeriodicScan(schedule string) {
+	time.Sleep(2 * time.Second) // Wait 2 seconds before the first scan
 	scanner := GetScanner()
+	scheduler := GetScheduler()
+
+	log.Info("Executing initial scan")
+	if err := scanner.RescanAll(context.Background(), false); err != nil {
+		log.Error("Error executing initial scan", err)
+	}
+
+	log.Info("Scheduling periodic scan", "schedule", schedule)
+	err := scheduler.Add(schedule, func() {
+		_ = scanner.RescanAll(context.Background(), false)
+	})
+	if err != nil {
+		log.Error("Error scheduling periodic scan", err)
+	}
+}
+
+func startScheduler() (func() error, func(err error)) {
+	log.Info("Starting scheduler")
+	scheduler := GetScheduler()
 	ctx, cancel := context.WithCancel(context.Background())
 
 	return func() error {
-			time.Sleep(2 * time.Second) // Wait 2 seconds before the first scan
-			scanner.Run(ctx, interval)
+			scheduler.Run(ctx)
 
 			return nil
 		}, func(err error) {
 			cancel()
 			if err != nil {
-				log.Error("Shutting down Scanner due to error", err)
+				log.Error("Shutting down Scheduler due to error", err)
 			} else {
-				log.Info("Shutting down Scanner")
+				log.Info("Shutting down Scheduler")
 			}
 		}
 }

cmd/wire_gen.go

@@ -6,16 +6,18 @@
 package cmd
 
 import (
+	"sync"
+
 	"github.com/google/wire"
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/core/transcoder"
 	"github.com/navidrome/navidrome/persistence"
 	"github.com/navidrome/navidrome/scanner"
+	"github.com/navidrome/navidrome/scheduler"
 	"github.com/navidrome/navidrome/server"
 	"github.com/navidrome/navidrome/server/app"
 	"github.com/navidrome/navidrome/server/events"
 	"github.com/navidrome/navidrome/server/subsonic"
-	"sync"
 )
 
 // Injectors from wire_injectors.go:
@@ -63,6 +65,11 @@ func createBroker() events.Broker {
 	return broker
 }
 
+func createScheduler() scheduler.Scheduler {
+	schedulerScheduler := scheduler.New()
+	return schedulerScheduler
+}
+
 // wire_injectors.go:
 
 var allProviders = wire.NewSet(core.Set, subsonic.New, app.New, persistence.New)
@@ -92,3 +99,16 @@ func GetBroker() events.Broker {
 	})
 	return brokerInstance
 }
+
+// Scheduler must be a Singleton
+var (
+	onceScheduler     sync.Once
+	schedulerInstance scheduler.Scheduler
+)
+
+func GetScheduler() scheduler.Scheduler {
+	onceScheduler.Do(func() {
+		schedulerInstance = createScheduler()
+	})
+	return schedulerInstance
+}

cmd/wire_injectors.go

@@ -9,6 +9,7 @@ import (
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/persistence"
 	"github.com/navidrome/navidrome/scanner"
+	"github.com/navidrome/navidrome/scheduler"
 	"github.com/navidrome/navidrome/server"
 	"github.com/navidrome/navidrome/server/app"
 	"github.com/navidrome/navidrome/server/events"
@@ -82,3 +83,22 @@ func createBroker() events.Broker {
 		events.NewBroker,
 	))
 }
+
+// Scheduler must be a Singleton
+var (
+	onceScheduler     sync.Once
+	schedulerInstance scheduler.Scheduler
+)
+
+func GetScheduler() scheduler.Scheduler {
+	onceScheduler.Do(func() {
+		schedulerInstance = createScheduler()
+	})
+	return schedulerInstance
+}
+
+func createScheduler() scheduler.Scheduler {
+	panic(wire.Build(
+		scheduler.New,
+	))
+}

conf/configuration.go

@@ -10,6 +10,7 @@ import (
 	"github.com/kr/pretty"
 	"github.com/navidrome/navidrome/consts"
 	"github.com/navidrome/navidrome/log"
+	"github.com/robfig/cron/v3"
 	"github.com/spf13/viper"
 )
 
@@ -22,6 +23,7 @@ type configOptions struct {
 	DbPath                  string
 	LogLevel                string
 	ScanInterval            time.Duration
+	ScanSchedule            string
 	SessionTimeout          time.Duration
 	BaseURL                 string
 	UILoginBackgroundURL    string
@@ -108,6 +110,11 @@ func Load() {
 	log.SetLevelString(Server.LogLevel)
 	log.SetLogSourceLine(Server.DevLogSourceLine)
 	log.SetRedacting(Server.EnableLogRedacting)
+
+	if err := validateScanSchedule(); err != nil {
+		os.Exit(1)
+	}
+
 	log.Debug(pretty.Sprintf("Loaded configuration from '%s': %# v\n", Server.ConfigFile, Server))
 
 	// Call init hooks
@@ -116,6 +123,30 @@ func Load() {
 	}
 }
 
+func validateScanSchedule() error {
+	if Server.ScanInterval != 0 {
+		log.Warn("ScanInterval is DEPRECATED. Please use ScanSchedule. See docs at https://navidrome.org/docs/usage/configuration-options/")
+		if Server.ScanSchedule != "@every 1m" {
+			log.Error("You cannot specify both ScanInterval and ScanSchedule, ignoring ScanInterval")
+		} else {
+			Server.ScanSchedule = fmt.Sprintf("@every %s", Server.ScanInterval)
+			log.Warn("Setting ScanSchedule", "schedule", Server.ScanSchedule)
+		}
+	}
+	if Server.ScanSchedule != "" {
+		if _, err := time.ParseDuration(Server.ScanSchedule); err == nil {
+			Server.ScanSchedule = "@every " + Server.ScanSchedule
+		}
+		c := cron.New()
+		_, err := c.AddFunc(Server.ScanSchedule, func() {})
+		if err != nil {
+			log.Error("Invalid ScanSchedule. Please read format spec at https://pkg.go.dev/github.com/robfig/cron#hdr-CRON_Expression_Format", "schedule", Server.ScanSchedule, err)
+			return err
+		}
+	}
+	return nil
+}
+
 // AddHook is used to register initialization code that should run as soon as the config is loaded
 func AddHook(hook func()) {
 	hooks = append(hooks, hook)
@@ -128,7 +159,8 @@ func init() {
 	viper.SetDefault("address", "0.0.0.0")
 	viper.SetDefault("port", 4533)
 	viper.SetDefault("sessiontimeout", consts.DefaultSessionTimeout)
-	viper.SetDefault("scaninterval", time.Minute)
+	viper.SetDefault("scaninterval", 0)
+	viper.SetDefault("scanschedule", "@every 1m")
 	viper.SetDefault("baseurl", "")
 	viper.SetDefault("uiloginbackgroundurl", consts.DefaultUILoginBackgroundURL)
 	viper.SetDefault("enabletranscodingconfig", false)

go.mod

@@ -34,6 +34,7 @@ require (
 	github.com/onsi/gomega v1.11.0
 	github.com/pelletier/go-toml v1.8.0 // indirect
 	github.com/pressly/goose v2.7.0+incompatible
+	github.com/robfig/cron/v3 v3.0.0 // indirect
 	github.com/sirupsen/logrus v1.8.1
 	github.com/spf13/afero v1.3.1 // indirect
 	github.com/spf13/cast v1.3.1 // indirect

go.sum

@@ -630,6 +630,8 @@ github.com/quasilyte/go-ruleguard/rules v0.0.0-20210203162857-b223e0831f88/go.mo
 github.com/quasilyte/go-ruleguard/rules v0.0.0-20210221215616-dfcc94e3dffd/go.mod h1:4cgAphtvu7Ftv7vOT2ZOYhC6CvBxZixcasr8qIOTA50=
 github.com/quasilyte/regex/syntax v0.0.0-20200407221936-30656e2c4a95 h1:L8QM9bvf68pVdQ3bCFZMDmnt9yqcMBro1pC7F+IPYMY=
 github.com/quasilyte/regex/syntax v0.0.0-20200407221936-30656e2c4a95/go.mod h1:rlzQ04UMyJXu/aOvhd8qT+hvDrFpiwqp8MRXDY9szc0=
+github.com/robfig/cron/v3 v3.0.0 h1:kQ6Cb7aHOHTSzNVNEhmp8EcWKLb4CbiMW9h9VyIhO4E=
+github.com/robfig/cron/v3 v3.0.0/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=

scanner/scanner.go

@@ -16,7 +16,6 @@ import (
 )
 
 type Scanner interface {
-	Run(ctx context.Context, interval time.Duration)
 	RescanAll(ctx context.Context, fullRescan bool) error
 	Status(mediaFolder string) (*StatusInfo, error)
 	Scanning() bool
@@ -72,23 +71,6 @@ func New(ds model.DataStore, cacheWarmer core.CacheWarmer, broker events.Broker)
 	return s
 }
 
-func (s *scanner) Run(ctx context.Context, interval time.Duration) {
-	ticker := time.NewTicker(interval)
-	defer ticker.Stop()
-	for {
-		err := s.RescanAll(ctx, false)
-		if err != nil {
-			log.Error(err)
-		}
-		select {
-		case <-ticker.C:
-			continue
-		case <-ctx.Done():
-			return
-		}
-	}
-}
-
 func (s *scanner) rescan(ctx context.Context, mediaFolder string, fullRescan bool) error {
 	folderScanner := s.folders[mediaFolder]
 	start := time.Now()

scheduler/log_adapter.go

@@ -0,0 +1,24 @@
+package scheduler
+
+import (
+	"github.com/navidrome/navidrome/log"
+)
+
+type logger struct{}
+
+func (l *logger) Info(msg string, keysAndValues ...interface{}) {
+	args := []interface{}{
+		"Scheduler: " + msg,
+	}
+	args = append(args, keysAndValues...)
+	log.Debug(args...)
+}
+
+func (l *logger) Error(err error, msg string, keysAndValues ...interface{}) {
+	args := []interface{}{
+		"Scheduler: " + msg,
+	}
+	args = append(args, keysAndValues...)
+	args = append(args, err)
+	log.Error(args...)
+}

scheduler/scheduler.go

@@ -0,0 +1,34 @@
+package scheduler
+
+import (
+	"context"
+
+	"github.com/robfig/cron/v3"
+)
+
+type Scheduler interface {
+	Run(ctx context.Context)
+	Add(crontab string, cmd func()) error
+}
+
+func New() Scheduler {
+	c := cron.New(cron.WithLogger(&logger{}))
+	return &scheduler{
+		c: c,
+	}
+}
+
+type scheduler struct {
+	c *cron.Cron
+}
+
+func (s *scheduler) Run(ctx context.Context) {
+	s.c.Start()
+	<-ctx.Done()
+	s.c.Stop()
+}
+
+func (s *scheduler) Add(crontab string, cmd func()) error {
+	_, err := s.c.AddFunc(crontab, cmd)
+	return err
+}