Socket.IO Redis adapter
The `@socket.io/redis-adapter` package allows broadcasting packets between multiple Socket.IO servers.
**Table of contents**
* [Supported features](#supported-features)
* [Security notice](#security-notice)
* [Installation](#installation)
* [Compatibility table](#compatibility-table)
* [Usage](#usage)
* [With the `redis` package](#with-the-redis-package)
* [With the `redis` package and a Redis cluster](#with-the-redis-package-and-a-redis-cluster)
* [With the `ioredis` package](#with-the-ioredis-package)
* [With the `ioredis` package and a Redis cluster](#with-the-ioredis-package-and-a-redis-cluster)
* [With Redis sharded Pub/Sub](#with-redis-sharded-pubsub)
* [With `redis`](#with-redis)
* [With `ioredis`](#with-ioredis)
* [Options](#options)
* [Default adapter](#default-adapter)
* [Sharded adapter](#sharded-adapter)
* [License](#license)
## Supported features
| Feature | `socket.io` version | Support |
|---------------------------------|---------------------|------------------------------------------------|
| Socket management | `4.0.0` | :white_check_mark: YES (since version `6.1.0`) |
| Inter-server communication | `4.1.0` | :white_check_mark: YES (since version `7.0.0`) |
| Broadcast with acknowledgements | `4.5.0` | :white_check_mark: YES (since version `7.2.0`) |
| Connection state recovery | `4.6.0` | :x: NO |
## Security notice
The Redis adapter assumes that Redis is part of the trusted internal infrastructure.
Messages exchanged through Redis Pub/Sub are not signed, encrypted, or authenticated by the adapter. Anyone able to publish to the adapter channels may be able to inject packets or control messages. Redis should therefore not be exposed to untrusted networks or shared with untrusted clients.
Please use Redis ACLs, authentication, TLS, firewall rules, private networking, and dedicated credentials/channel permissions where appropriate.
## Installation
```
npm install @socket.io/redis-adapter
```
## Compatibility table
| Redis Adapter version | Socket.IO server version |
|-----------------------|--------------------------|
| 4.x | 1.x |
| 5.x | 2.x |
| 6.0.x | 3.x |
| 6.1.x | 4.x |
| 7.x and above | 4.3.1 and above |
## Usage
### With the `redis` package
```js
import { createClient } from "redis";
import { Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-adapter";
const pubClient = createClient({ url: "redis://localhost:6379" });
const subClient = pubClient.duplicate();
await Promise.all([
pubClient.connect(),
subClient.connect()
]);
const io = new Server({
adapter: createAdapter(pubClient, subClient)
});
io.listen(3000);
```
### With the `redis` package and a Redis cluster
```js
import { createCluster } from "redis";
import { Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-adapter";
const pubClient = createCluster({
rootNodes: [
{
url: "redis://localhost:7000",
},
{
url: "redis://localhost:7001",
},
{
url: "redis://localhost:7002",
},
],
});
const subClient = pubClient.duplicate();
await Promise.all([
pubClient.connect(),
subClient.connect()
]);
const io = new Server({
adapter: createAdapter(pubClient, subClient)
});
io.listen(3000);
```
### With the `ioredis` package
```js
import { Redis } from "ioredis";
import { Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-adapter";
const pubClient = new Redis();
const subClient = pubClient.duplicate();
const io = new Server({
adapter: createAdapter(pubClient, subClient)
});
io.listen(3000);
```
### With the `ioredis` package and a Redis cluster
```js
import { Cluster } from "ioredis";
import { Server } from "socket.io";
import { createAdapter } from "@socket.io/redis-adapter";
const pubClient = new Cluster([
{
host: "localhost",
port: 7000,
},
{
host: "localhost",
port: 7001,
},
{
host: "localhost",
port: 7002,
},
]);
const subClient = pubClient.duplicate();
const io = new Server({
adapter: createAdapter(pubClient, subClient)
});
io.listen(3000);
```
### With Redis sharded Pub/Sub
Sharded Pub/Sub was introduced in Redis 7.0 in order to help scaling the usage of Pub/Sub in cluster mode.
Reference: https://redis.io/docs/interact/pubsub/#sharded-pubsub
A dedicated adapter can be created with the `createShardedAdapter()` method:
#### With `redis`
Minimum requirements:
- Redis 7.0
- [`
[email protected]`](https://github.com/redis/node-redis/commit/3b1bad229674b421b2bc6424155b20d4d3e45bd1)
```js
import { Server } from "socket.io";
import { createClient } from "redis";
import { createShardedAdapter } from "@socket.io/redis-adapter";
const pubClient = createClient({ host: "localhost", port: 6379 });
const subClient = pubClient.duplicate();
await Promise.all([
pubClient.connect(),
subClient.connect()
]);
const io = new Server({
adapter: createShardedAdapter(pubClient, subClient)
});
io.listen(3000);
```
#### With `ioredis`
Minimum requirements:
- Redis 7.0
- [`
[email protected]`](https://github.com/redis/ioredis/pull/1956)
Please note that the `shardedSubscribers` option is required to enable sharded Pub/Sub.
```js
import { Cluster } from "ioredis";
import { Server } from "socket.io";
import { createShardedAdapter } from "@socket.io/redis-adapter";
const pubClient = new Cluster(
[
{
host: "localhost",
port: 7000,
},
{
host: "localhost",
port: 7001,
},
{
host: "localhost",
port: 7002,
},
],
{
shardedSubscribers: true,
}
);
const subClient = pubClient.duplicate();
const io = new Server({
adapter: createShardedAdapter(pubClient, subClient)
});
io.listen(3000);
```
## Options
### Default adapter
| Name | Description | Default value |
|------------------------------------|-------------------------------------------------------------------------------|---------------|
| `key` | The prefix for the Redis Pub/Sub channels. | `socket.io` |
| `requestsTimeout` | After this timeout the adapter will stop waiting from responses to request. | `5_000` |
| `publishOnSpecificResponseChannel` | Whether to publish a response to the channel specific to the requesting node. | `false` |
| `parser` | The parser to use for encoding and decoding messages sent to Redis. | `-` |
### Sharded adapter
| Name | Description | Default value |
|--------------------|-----------------------------------------------------------------------------------------|---------------|
| `channelPrefix` | The prefix for the Redis Pub/Sub channels. | `socket.io` |
| `subscriptionMode` | The subscription mode impacts the number of Redis Pub/Sub channels used by the adapter. | `dynamic` |
## License
[MIT](LICENSE)