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socket.io-redis
Advanced tools
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const io = require('socket.io')(3000);
const redisAdapter = require('socket.io-redis');
io.adapter(redisAdapter({ host: 'localhost', port: 6379 }));
import { Server } from 'socket.io';
import redisAdapter from 'socket.io-redis';
const io = new Server(3000);
io.adapter(redisAdapter({ host: 'localhost', port: 6379 }));
// npm i -D @types/redis
import { Server } from 'socket.io';
import { createAdapter } from 'socket.io-redis';
import { RedisClient } from 'redis';
const io = new Server(8080);
const pubClient = new RedisClient({ host: 'localhost', port: 6379 });
const subClient = pubClient.duplicate();
io.adapter(createAdapter({ pubClient, subClient }));
By running Socket.IO with the socket.io-redis
adapter you can run
multiple Socket.IO instances in different processes or servers that can
all broadcast and emit events to and from each other.
So any of the following commands:
io.emit('hello', 'to all clients');
io.to('room42').emit('hello', "to all clients in 'room42' room");
io.on('connection', (socket) => {
socket.broadcast.emit('hello', 'to all clients except sender');
socket.to('room42').emit('hello', "to all clients in 'room42' room except sender");
});
will properly be broadcast to the clients through the Redis Pub/Sub mechanism.
If you need to emit events to socket.io instances from a non-socket.io process, you should use socket.io-emitter.
Redis Adapter version | Socket.IO server version |
---|---|
4.x | 1.x |
5.x | 2.x |
6.0.x | 3.x |
6.1.x and above | 4.x |
This adapter extends the in-memory adapter that is included by default with the Socket.IO server.
The in-memory adapter stores the relationships between Sockets and Rooms in two Maps.
When you run socket.join("room21")
, here's what happens:
console.log(adapter.rooms); // Map { "room21" => Set { "mdpk4kxF5CmhwfCdAHD8" } }
console.log(adapter.sids); // Map { "mdpk4kxF5CmhwfCdAHD8" => Set { "mdpk4kxF5CmhwfCdAHD8", room21" } }
// "mdpk4kxF5CmhwfCdAHD8" being the ID of the given socket
Those two Maps are then used when broadcasting:
io.emit()
) loops through the sids
Map, and send the packet to all socketsio.to("room21").emit()
) loops through the Set in the rooms
Map, and sends the packet to all matching socketsThe Redis adapter extends the broadcast function of the in-memory adapter: the packet is also published to a Redis channel (see below for the format of the channel name).
Each Socket.IO server receives this packet and broadcasts it to its own list of connected sockets.
To check what's happening on your Redis instance:
$ redis-cli
127.0.0.1:6379> PSUBSCRIBE *
Reading messages... (press Ctrl-C to quit)
1) "psubscribe"
2) "*"
3) (integer) 1
1) "pmessage"
2) "*"
3) "socket.io#/#" (a broadcast to all sockets or to a list of rooms)
4) <the packet content>
1) "pmessage"
2) "*"
3) "socket.io#/#room21#" (a broadcast to a single room)
4) <the packet content>
Note: no data is stored in Redis itself
There are 3 Redis subscriptions per namespace:
<prefix>#<namespace>#*
(glob)<prefix>-request#<namespace>#
<prefix>-response#<namespace>#
The request and response channels are used in the additional methods exposed by the Redis adapter, like RedisAdapter#allRooms().
uri
is a string like localhost:6379
where your redis server
is located. For a list of options see below.
The following options are allowed:
key
: the name of the key to pub/sub events on as prefix (socket.io
)host
: host to connect to redis on (localhost
)port
: port to connect to redis on (6379
)pubClient
: optional, the redis client to publish events onsubClient
: optional, the redis client to subscribe to events onrequestsTimeout
: optional, after this timeout the adapter will stop waiting from responses to request (5000ms
)If you decide to supply pubClient
and subClient
, make sure you use
node_redis as a client or one
with an equivalent API.
The redis adapter instances expose the following properties
that a regular Adapter
does not
uid
prefix
pubClient
subClient
requestsTimeout
Returns the list of socket IDs connected to rooms
across all nodes. See Namespace#allSockets()
const sockets = await io.of('/').adapter.sockets();
console.log(sockets); // a Set containing all the connected socket ids
const sockets = await io.of('/').adapter.sockets(new Set(['room1', 'room2']));
console.log(sockets); // a Set containing the socket ids in 'room1' or in 'room2'
// this method is also exposed by the Server instance
const sockets = await io.in('room3').allSockets();
console.log(sockets); // a Set containing the socket ids in 'room3'
Returns the list of all rooms.
const rooms = await io.of('/').adapter.allRooms();
console.log(rooms); // a Set containing all rooms (across every node)
Makes the socket with the given id join the room.
try {
await io.of('/').adapter.remoteJoin('<my-id>', 'room1');
} catch (e) {
// the socket was not found
}
Makes the socket with the given id leave the room.
try {
await io.of('/').adapter.remoteLeave('<my-id>', 'room1');
} catch (e) {
// the socket was not found
}
Makes the socket with the given id to get disconnected. If close
is set to true, it also closes the underlying socket.
try {
await io.of('/').adapter.remoteDisconnect('<my-id>', true);
} catch (e) {
// the socket was not found
}
Access the pubClient
and subClient
properties of the
Redis Adapter instance to subscribe to its error
event:
const adapter = require('socket.io-redis')('localhost:6379');
adapter.pubClient.on('error', function(){});
adapter.subClient.on('error', function(){});
The errors emitted from pubClient
and subClient
will
also be forwarded to the adapter instance:
const io = require('socket.io')(3000);
const redisAdapter = require('socket.io-redis');
io.adapter(redisAdapter({ host: 'localhost', port: 6379 }));
io.of('/').adapter.on('error', function(){});
If you need to create a redisAdapter to a redis instance that has a password, use pub/sub options instead of passing a connection string.
const redis = require('redis');
const redisAdapter = require('socket.io-redis');
const pubClient = redis.createClient(port, host, { auth_pass: "pwd" });
const subClient = pubClient.duplicate();
io.adapter(redisAdapter({ pubClient, subClient }));
const io = require('socket.io')(3000);
const redisAdapter = require('socket.io-redis');
const Redis = require('ioredis');
const startupNodes = [
{
port: 6380,
host: '127.0.0.1'
},
{
port: 6381,
host: '127.0.0.1'
}
];
io.adapter(redisAdapter({
pubClient: new Redis.Cluster(startupNodes),
subClient: new Redis.Cluster(startupNodes)
}));
const io = require('socket.io')(3000);
const redisAdapter = require('socket.io-redis');
const Redis = require('ioredis');
const options = {
sentinels: [
{ host: 'somehost1', port: 26379 },
{ host: 'somehost2', port: 26379 }
],
name: 'master01'
};
io.adapter(redisAdapter({
pubClient: new Redis(options),
subClient: new Redis(options)
}));
The socket.io-redis
adapter broadcasts and receives messages on particularly named Redis channels. For global broadcasts the channel name is:
prefix + '#' + namespace + '#'
In broadcasting to a single room the channel name is:
prefix + '#' + namespace + '#' + room + '#'
prefix
: The base channel name. Default value is socket.io
. Changed by setting opts.key
in adapter(opts)
constructornamespace
: See https://github.com/socketio/socket.io#namespace.room
: Used if targeting a specific room.A number of other libraries adopt this protocol including:
MIT
FAQs
[![Build Status](https://github.com/socketio/socket.io-redis/workflows/CI/badge.svg?branch=master)](https://github.com/socketio/socket.io-redis/actions) [![NPM version](https://badge.fury.io/js/socket.io-redis.svg)](http://badge.fury.io/js/socket.io-redis
The npm package socket.io-redis receives a total of 76,398 weekly downloads. As such, socket.io-redis popularity was classified as popular.
We found that socket.io-redis demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 2 open source maintainers collaborating on the project.
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