From c10f59ea49762f34b9f55b9571fa09d556ea1b3e Mon Sep 17 00:00:00 2001
From: Bernd Verst <github@bernd.dev>
Date: Thu, 9 Nov 2023 19:23:31 -0800
Subject: [PATCH] Redis: recover subscription if group or stream deleted
 (#3221)

Signed-off-by: Bernd Verst <github@bernd.dev>
---
 pubsub/redis/redis.go | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/pubsub/redis/redis.go b/pubsub/redis/redis.go
index 899ba1360..7cc1297fc 100644
--- a/pubsub/redis/redis.go
+++ b/pubsub/redis/redis.go
@@ -18,6 +18,7 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -108,15 +109,22 @@ func (r *redisStreams) Publish(ctx context.Context, req *pubsub.PublishRequest)
 	return nil
 }
 
+func (r *redisStreams) CreateConsumerGroup(ctx context.Context, stream string) error {
+	err := r.client.XGroupCreateMkStream(ctx, stream, r.clientSettings.ConsumerID, "0")
+	// Ignore BUSYGROUP errors
+	if err != nil && err.Error() != "BUSYGROUP Consumer Group name already exists" {
+		r.logger.Errorf("redis streams: %s", err)
+		return err
+	}
+	return nil
+}
+
 func (r *redisStreams) Subscribe(ctx context.Context, req pubsub.SubscribeRequest, handler pubsub.Handler) error {
 	if r.closed.Load() {
 		return errors.New("component is closed")
 	}
 
-	err := r.client.XGroupCreateMkStream(ctx, req.Topic, r.clientSettings.ConsumerID, "0")
-	// Ignore BUSYGROUP errors
-	if err != nil && err.Error() != "BUSYGROUP Consumer Group name already exists" {
-		r.logger.Errorf("redis streams: %s", err)
+	if err := r.CreateConsumerGroup(ctx, req.Topic); err != nil {
 		return err
 	}
 
@@ -242,6 +250,11 @@ func (r *redisStreams) pollNewMessagesLoop(ctx context.Context, stream string, h
 		streams, err := r.client.XReadGroupResult(ctx, r.clientSettings.ConsumerID, r.clientSettings.ConsumerID, []string{stream, ">"}, int64(r.clientSettings.QueueDepth), time.Duration(r.clientSettings.ReadTimeout))
 		if err != nil {
 			if !errors.Is(err, r.client.GetNilValueError()) && err != context.Canceled {
+				if strings.Contains(err.Error(), "NOGROUP") {
+					r.logger.Warnf("redis streams: consumer group %s does not exist for stream %s. This could mean the server experienced data loss, or the group/stream was deleted.", r.clientSettings.ConsumerID, stream)
+					r.logger.Warnf("redis streams: recreating group %s for stream %s", r.clientSettings.ConsumerID, stream)
+					r.CreateConsumerGroup(ctx, stream)
+				}
 				r.logger.Errorf("redis streams: error reading from stream %s: %s", stream, err)
 			}
 			continue