# ioredis — Robust Full-Featured Redis Client for Node.js

> A performance-focused Redis client for Node.js with built-in support for Cluster, Sentinel, Streams, Lua scripting, and pipelining.

## Install

Save as a script file and run:

# ioredis — Robust Full-Featured Redis Client for Node.js

## Quick Use
```bash
npm install ioredis
```
```js
import Redis from 'ioredis';
const redis = new Redis(); // connects to localhost:6379
await redis.set('key', 'value');
const val = await redis.get('key'); // "value"
```

## Introduction
ioredis is a robust Redis client for Node.js maintained by the Redis organization. It offers first-class support for Redis Cluster, Sentinel high-availability, Streams, pipelining, and Lua scripting — making it the preferred client for production applications that need reliability and performance beyond what simpler clients provide.

## What ioredis Does
- Connects to standalone Redis, Redis Cluster, and Redis Sentinel topologies
- Pipelines multiple commands into a single network round-trip for throughput
- Executes server-side Lua scripts with automatic EVALSHA caching
- Subscribes to Pub/Sub channels and handles pattern-based subscriptions
- Reads and writes to Redis Streams with consumer group support

## Architecture Overview
ioredis uses a single TCP connection per client instance with an internal command queue. Commands are serialized using the RESP protocol and flushed in batches when pipelining. The Cluster driver maintains a slot map and routes commands to the correct shard, handling MOVED and ASK redirections transparently. Sentinel support monitors master failovers and reconnects automatically.

## Self-Hosting & Configuration
- Install via npm — pure JavaScript with optional native parser for extra speed
- Pass connection options as an object or a Redis URL string: `new Redis('redis://user:pass@host:6379/0')`
- Enable TLS with `tls: {}` for encrypted connections to managed Redis services
- Configure automatic reconnect with `retryStrategy` for resilient long-lived connections
- Use `lazyConnect: true` to defer connection until the first command is issued

## Key Features
- Transparent Redis Cluster support with client-side slot routing and pipeline splitting
- Sentinel-aware failover: auto-discovers new masters and reconnects subscribers
- Built-in Lua script management with SHA caching to avoid resending script bodies
- Offline queue buffers commands during reconnection, replaying them once connected
- Over 15,000 GitHub stars and 12 million weekly npm downloads

## Comparison with Similar Tools
- **node-redis** — the official Redis client; ioredis has richer Cluster and Sentinel support out of the box
- **redis-py (Python)** — Python equivalent; ioredis is the Node.js counterpart with async-native design
- **Jedis (Java)** — synchronous Java client; ioredis is fully async and non-blocking
- **Lettuce (Java)** — reactive Java client; ioredis achieves similar async patterns in Node.js
- **Upstash Redis** — HTTP-based serverless client; ioredis uses persistent TCP for lower latency

## FAQ
**Q: Should I use ioredis or node-redis?**
A: ioredis is preferred for Redis Cluster and Sentinel deployments. node-redis has improved recently but ioredis remains more mature for complex topologies.

**Q: Does it support Redis 7 features?**
A: Yes. ioredis supports client-side caching, sharded Pub/Sub, and function commands available in Redis 7+.

**Q: How do I handle connection failures in production?**
A: Configure `retryStrategy` to return a delay in milliseconds. ioredis will reconnect automatically and replay queued commands.

**Q: Can I use ioredis with Valkey?**
A: Yes. Valkey is API-compatible with Redis, and ioredis connects to it without any code changes.

## Sources
- https://github.com/redis/ioredis
- https://redis.github.io/ioredis/

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Source: https://tokrepo.com/en/workflows/asset-f59d16a2
Author: Script Depot