Reconfigure typing and presence streams upon nats reconnection (#48)

When NATS is restarted in single mode, in-memory streams are lost, which makes dendrite unable to publish presence and typing events. We attempt to recreate streams upon reconnection event, since it will happen when NATS is restarted.
2025-12-07 06:53:09 -06:00 · 2022-11-03 15:29:01 +01:00 · 2022-11-03 15:29:01 +01:00 · 23584d9738
parent 610c73c1f5
commit 23584d9738
1 changed files with 69 additions and 82 deletions
--- a/setup/jetstream/nats.go
+++ b/setup/jetstream/nats.go
@ -8,13 +8,13 @@ import (
 	"sync"
 	"time"

-	"github.com/getsentry/sentry-go"
 	"github.com/sirupsen/logrus"

 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/setup/process"

 	natsserver "github.com/nats-io/nats-server/v2/server"
+	"github.com/nats-io/nats.go"
 	natsclient "github.com/nats-io/nats.go"
 )

@ -36,7 +36,7 @@ func (s *NATSInstance) Prepare(process *process.ProcessContext, cfg *config.JetS
 	defer natsLock.Unlock()
 	// check if we need an in-process NATS Server
 	if len(cfg.Addresses) != 0 {
-		return setupNATS(process, cfg, nil)
+		return setupNATS(cfg, nil)
 	}
 	if s.Server == nil {
 		var err error
@ -72,18 +72,29 @@ func (s *NATSInstance) Prepare(process *process.ProcessContext, cfg *config.JetS
 	if err != nil {
 		logrus.Fatalln("Failed to create NATS client")
 	}
-	return setupNATS(process, cfg, nc)
+	return setupNATS(cfg, nc)
 }

-func setupNATS(process *process.ProcessContext, cfg *config.JetStream, nc *natsclient.Conn) (natsclient.JetStreamContext, *natsclient.Conn) {
+func setupNATS(cfg *config.JetStream, nc *natsclient.Conn) (natsclient.JetStreamContext, *natsclient.Conn) {
+	var s nats.JetStreamContext
+	var err error
 	if nc == nil {
-		var err error
 		opts := []natsclient.Option{
 			natsclient.DisconnectErrHandler(func(c *natsclient.Conn, err error) {
 				logrus.WithError(err).Error("nats connection: disconnected")
 			}),
 			natsclient.ReconnectHandler(func(_ *natsclient.Conn) {
 				logrus.Info("nats connection: client reconnected")
+				for _, stream := range []*nats.StreamConfig{
+					streams[6],
+					streams[10],
+				} {
+					err = configureStream(stream, cfg, s)
+					if err != nil {
+						logrus.WithError(err).WithField("stream", stream.Name).Error("unable to configure a stream")
+					}
+
+				}
 			}),
 			natsclient.ClosedHandler(func(_ *natsclient.Conn) {
 				logrus.Info("nats connection: client closed")
@ -101,89 +112,16 @@ func setupNATS(process *process.ProcessContext, cfg *config.JetStream, nc *natsc
 		}
 	}

-	s, err := nc.JetStream()
+	s, err = nc.JetStream()
 	if err != nil {
 		logrus.WithError(err).Panic("Unable to get JetStream context")
 		return nil, nil
 	}

 	for _, stream := range streams { // streams are defined in streams.go
-		name := cfg.Prefixed(stream.Name)
-		info, err := s.StreamInfo(name)
-		if err != nil && err != natsclient.ErrStreamNotFound {
-			logrus.WithError(err).Fatal("Unable to get stream info")
-		}
-		subjects := stream.Subjects
-		if len(subjects) == 0 {
-			// By default we want each stream to listen for the subjects
-			// that are either an exact match for the stream name, or where
-			// the first part of the subject is the stream name. ">" is a
-			// wildcard in NATS for one or more subject tokens. In the case
-			// that the stream is called "Foo", this will match any message
-			// with the subject "Foo", "Foo.Bar" or "Foo.Bar.Baz" etc.
-			subjects = []string{name, name + ".>"}
-		}
-		if info != nil {
-			switch {
-			case !reflect.DeepEqual(info.Config.Subjects, subjects):
-				fallthrough
-			case info.Config.Retention != stream.Retention:
-				fallthrough
-			case info.Config.Storage != stream.Storage:
-				if err = s.DeleteStream(name); err != nil {
-					logrus.WithError(err).Fatal("Unable to delete stream")
-				}
-				info = nil
-			}
-		}
-		if info == nil {
-			// If we're trying to keep everything in memory (e.g. unit tests)
-			// then overwrite the storage policy.
-			if cfg.InMemory {
-				stream.Storage = natsclient.MemoryStorage
-			}
-
-			// Namespace the streams without modifying the original streams
-			// array, otherwise we end up with namespaces on namespaces.
-			namespaced := *stream
-			namespaced.Name = name
-			namespaced.Subjects = subjects
-			if _, err = s.AddStream(&namespaced); err != nil {
-				logger := logrus.WithError(err).WithFields(logrus.Fields{
-					"stream":   namespaced.Name,
-					"subjects": namespaced.Subjects,
-				})
-
-				// If the stream was supposed to be in-memory to begin with
-				// then an error here is fatal so we'll give up.
-				if namespaced.Storage == natsclient.MemoryStorage {
-					logger.WithError(err).Fatal("Unable to add in-memory stream")
-				}
-
-				// The stream was supposed to be on disk. Let's try starting
-				// Dendrite with the stream in-memory instead. That'll mean that
-				// we can't recover anything that was queued on the disk but we
-				// will still be able to start and run hopefully in the meantime.
-				logger.WithError(err).Error("Unable to add stream")
-				sentry.CaptureException(fmt.Errorf("Unable to add stream %q: %w", namespaced.Name, err))
-
-				namespaced.Storage = natsclient.MemoryStorage
-				if _, err = s.AddStream(&namespaced); err != nil {
-					// We tried to add the stream in-memory instead but something
-					// went wrong. That's an unrecoverable situation so we will
-					// give up at this point.
-					logger.WithError(err).Fatal("Unable to add in-memory stream")
-				}
-
-				if stream.Storage != namespaced.Storage {
-					// We've managed to add the stream in memory.  What's on the
-					// disk will be left alone, but our ability to recover from a
-					// future crash will be limited. Yell about it.
-					err := fmt.Errorf("Stream %q is running in-memory; this may be due to data corruption in the JetStream storage directory", namespaced.Name)
-					sentry.CaptureException(err)
-					process.Degraded(err)
-				}
-			}
+		err = configureStream(stream, cfg, s)
+		if err != nil {
+			logrus.WithError(err).WithField("stream", stream.Name).Fatal("unable to configure a stream")
 		}
 	}

@ -213,3 +151,52 @@ func setupNATS(process *process.ProcessContext, cfg *config.JetStream, nc *natsc

 	return s, nc
 }
+
+func configureStream(stream *nats.StreamConfig, cfg *config.JetStream, s nats.JetStreamContext) error {
+	name := cfg.Prefixed(stream.Name)
+	info, err := s.StreamInfo(name)
+	if err != nil && err != natsclient.ErrStreamNotFound {
+		return fmt.Errorf("get stream info: %w", err)
+	}
+	subjects := stream.Subjects
+	if len(subjects) == 0 {
+		// By default we want each stream to listen for the subjects
+		// that are either an exact match for the stream name, or where
+		// the first part of the subject is the stream name. ">" is a
+		// wildcard in NATS for one or more subject tokens. In the case
+		// that the stream is called "Foo", this will match any message
+		// with the subject "Foo", "Foo.Bar" or "Foo.Bar.Baz" etc.
+		subjects = []string{name, name + ".>"}
+	}
+	if info != nil {
+		switch {
+		case !reflect.DeepEqual(info.Config.Subjects, subjects):
+			fallthrough
+		case info.Config.Retention != stream.Retention:
+			fallthrough
+		case info.Config.Storage != stream.Storage:
+			if err = s.DeleteStream(name); err != nil {
+				return fmt.Errorf("delete stream: %w", err)
+			}
+			info = nil
+		}
+	}
+	if info == nil {
+		// If we're trying to keep everything in memory (e.g. unit tests)
+		// then overwrite the storage policy.
+		if cfg.InMemory {
+			stream.Storage = natsclient.MemoryStorage
+		}
+
+		// Namespace the streams without modifying the original streams
+		// array, otherwise we end up with namespaces on namespaces.
+		namespaced := *stream
+		namespaced.Name = name
+		namespaced.Subjects = subjects
+		if _, err = s.AddStream(&namespaced); err != nil {
+			return fmt.Errorf("add stream: %w", err)
+		}
+		logrus.Infof("stream created: %s", stream.Name)
+	}
+	return nil
+}