Redis

Overview

The Redis connector joins a consumer group on the streams you choose, so each entry starts exactly one run and nothing is read twice. It can also listen for expired keys and pub/sub messages, and every event shows up in the trace of the run it started.

Teams use it to send a Twilio text when a delivery job lands on a stream, to clean up records in Postgres when a session key expires and to feed rate limit counters back to their API.

Supported versions

• Redis 6.2 to 8.x and Valkey 7.2 and later, standalone or cluster

• Redis Cloud, Amazon ElastiCache and MemoryDB, Azure Cache for Redis and Upstash

• Connections over TLS with ACL users

How streams work

Tessel creates a consumer group on each stream and reads new entries with XREADGROUP. An entry is acknowledged with XACK only after its run has started, so a dropped connection leaves it pending and Tessel claims it again on reconnect.

XGROUP CREATE orders:events tessel $ MKSTREAM

XREADGROUP GROUP tessel worker-1
  COUNT 100 BLOCK 5000
  STREAMS orders:events

XGROUP CREATE orders:events tessel $ MKSTREAM

XREADGROUP GROUP tessel worker-1
  COUNT 100 BLOCK 5000
  STREAMS orders:events

XGROUP CREATE orders:events tessel $ MKSTREAM

XREADGROUP GROUP tessel worker-1
  COUNT 100 BLOCK 5000
  STREAMS orders:events

Expired keys and pub/sub

Key expiry triggers need notify-keyspace-events set to include Ex. Keyspace notifications and pub/sub are fire and forget, so messages sent while Tessel is disconnected are lost. Use streams for anything a workflow must not miss.

Permissions needed

Create an ACL user for Tessel scoped to the keys and channels it reads. Grant write commands only on the key patterns workflows write to.

• +xreadgroup, +xack and +xgroup on the stream keys you read

• +subscribe and +publish on the channel patterns you use

• +get, +set and +incr only on patterns like ~tessel:*