🚀 Redis Essentials: CLI, Configuration, Persistence, and Usage

⚡ Quick Dive

Overview & Key Takeaways

Redis is a fast, in-memory key-value store widely used for caching, session storage, pub/sub, and real-time analytics. This guide covers how to use Redis from the CLI, configure it for production, manage persistence, and apply practical usage patterns.

⚡ 1. Redis CLI Basics

🔹 Connecting to Redis

redis-cli
redis-cli -h 127.0.0.1 -p 6379 -a yourpassword

🔹 Common Commands

SET user:1 "John"
GET user:1

DEL user:1
EXISTS user:1
TTL user:1

KEYS user:* 

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## 📖 Extended Guide

Redis is a fast, in-memory key-value store widely used for **caching**, **session storage**, **pub/sub**, and **real-time analytics**. This guide covers how to use Redis from the CLI, configure it for production, manage persistence, and apply practical usage patterns.

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## ⚡ 1. Redis CLI Basics

### 🔹 Connecting to Redis

redis-cli redis-cli -h 127.0.0.1 -p 6379 -a yourpassword

### 🔹 Common Commands

SET user:1 "John" GET user:1

DEL user:1 EXISTS user:1 TTL user:1

KEYS user:* -- (⚠️ avoid in production) SCAN 0 MATCH user:* COUNT 100

FLUSHDB -- flush current DB FLUSHALL -- flush all DBs

> Use `SCAN` instead of `KEYS` in production to avoid blocking.

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## ⚙️ 2. Configuration for Production

### 🔹 Config File

Default path: `/etc/redis/redis.conf` (Debian) or `/etc/redis.conf` (Alpine/Docker)

Important entries:

```conf
bind 127.0.0.1
port 6379
requirepass yourpassword
timeout 300
maxmemory 512mb
maxmemory-policy allkeys-lru
appendonly yes
save 900 1
save 300 10

# Test config
redis-server /etc/redis/redis.conf --test-memory 512

# Restart service (Debian)
sudo systemctl restart redis

🔐 3. Access Control & Security

🔹 Authentication

Enable in config:

requirepass s3cret

Or at runtime:

AUTH s3cret

Use Redis ACLs (redis >= 6.0) for fine-grained control:

ACL SETUSER readonly on >password ~* +@read
ACL SETUSER writer on >password ~* +@write

💾 4. Persistence Modes

Redis supports two main persistence strategies:

🔹 AOF (Append-Only File)

• Safer, logs each write operation
• Config:

appendonly yes
appendfsync everysec

🔹 RDB Snapshots

• Periodic full memory snapshots
• Config:

save 900 1
save 300 10

Backups are written to:

• /var/lib/redis/dump.rdb
• /var/lib/redis/appendonly.aof

# Trigger save manually
SAVE         # blocking
BGSAVE       # non-blocking

🧠 5. Redis Data Structures

🛰️ 6. Redis Pub/Sub

For event messaging and notifications between services:

# Terminal A
SUBSCRIBE events:signup

# Terminal B
PUBLISH events:signup "new_user_id:123"

Redis Pub/Sub is fast but not durable — not guaranteed to deliver if subscriber is offline.

🔄 7. Use as a Cache (with TTLs)

# Set with TTL
SET session:abc123 "user data" EX 3600

# Get TTL
TTL session:abc123

# Atomic get+set+expire
SET mykey "value" EX 10 NX

Common eviction policies (set in config):

• allkeys-lru (least recently used)
• volatile-ttl (shortest time to live)
• noeviction (reject writes when full)

Use INFO memory to track memory usage.

🔍 8. Monitoring Redis

🔹 Stats and Info

INFO          -- All stats
INFO memory   -- Memory-specific
MONITOR       -- Live command feed (verbose)
CLIENT LIST   -- Connected clients

🔹 Logging

• Logs found in /var/log/redis/redis-server.log
• Verbosity set in config: loglevel notice

🧪 9. Useful Tools

• redis-cli – default CLI tool
• RedisInsight – official GUI dashboard
• redis-benchmark – test performance

redis-benchmark -n 100000 -q -P 10

• RDB Tools – inspect .rdb snapshots
• redis-commander – Node-based GUI for live keys

🛡️ 10. Reliability Tips

• Always set maxmemory and eviction policy in production
• Use AOF for safer persistence
• Use replication (slaveof, replicaof) for HA
• Combine with Sentinel or Redis Cluster for fault tolerance
• Protect Redis from the internet (bind, password, firewalls)

📚 Resources

• Redis Official Docs
• Redis CLI Reference
• RedisInsight Dashboard

✅ Summary