Socket.IO Redis Streams adapter
The @socket.io/redis-streams-adapter package allows broadcasting packets between multiple Socket.IO servers.
Supported features:
Related packages:
- Redis adapter: https://github.com/socketio/socket.io-redis-adapter/
- Redis emitter: https://github.com/socketio/socket.io-redis-emitter/
- MongoDB adapter: https://github.com/socketio/socket.io-mongo-adapter/
- MongoDB emitter: https://github.com/socketio/socket.io-mongo-emitter/
- Postgres adapter: https://github.com/socketio/socket.io-postgres-adapter/
- Postgres emitter: https://github.com/socketio/socket.io-postgres-emitter/
Table of contents
Installation
npm install @socket.io/redis-streams-adapter redis
Usage
import { createClient } from "redis";
import { Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-streams-adapter";
const redisClient = createClient({ url: "redis://localhost:6379" });
await redisClient.connect();
const io = new Server({
adapter: createAdapter(redisClient)
});
io.listen(3000);Options
| Name | Description | Default value |
|---|---|---|
streamName |
The name of the Redis stream. | socket.io |
maxLen |
The maximum size of the stream. Almost exact trimming (~) is used. | 10_000 |
readCount |
The number of elements to fetch per XREAD call. | 100 |
heartbeatInterval |
The number of ms between two heartbeats. | 5_000 |
heartbeatTimeout |
The number of ms without heartbeat before we consider a node down. | 10_000 |
How it works
The adapter will use a Redis stream to forward events between the Socket.IO servers.
Notes:
- a single stream is used for all namespaces
- the
maxLenoption allows to limit the size of the stream - unlike the adapter based on Redis PUB/SUB mechanism, this adapter will properly handle any temporary disconnection to the Redis server and resume the stream
- if connection state recovery is enabled, the sessions will be stored in Redis as a classic key/value pair