Knowledgebase

Redis is a fast, in-memory data store used as a cache, session store, message broker, and queue backend. It dramatically reduces database load and speeds up applications like WordPress, Laravel, and Node.js APIs.

Prerequisites

• Ubuntu 22.04/24.04 or Debian 11/12 VPS
• Root or sudo access

Step 1 — Install Redis

sudo apt update
sudo apt install redis-server -y

Step 2 — Enable and Start Redis

sudo systemctl enable redis-server
sudo systemctl start redis-server
sudo systemctl status redis-server

Step 3 — Test the Connection

redis-cli ping

Expected response: PONG

Step 4 — Secure Redis

sudo nano /etc/redis/redis.conf

Set a strong password:

requirepass CHANGE_ME_STRONG_PASSWORD

Confirm Redis only binds to localhost (default) unless remote access is genuinely required:

bind 127.0.0.1 -::1

Disable dangerous commands in production if not needed:

rename-command FLUSHALL ""
rename-command FLUSHDB ""

Step 5 — Restart Redis

sudo systemctl restart redis-server

Step 6 — Test Authentication

redis-cli
AUTH CHANGE_ME_STRONG_PASSWORD
PING

Basic Redis Commands

SET key value
GET key
DEL key
EXPIRE key 60
TTL key
KEYS *
FLUSHALL

Setting a Memory Limit and Eviction Policy

maxmemory 256mb
maxmemory-policy allkeys-lru

allkeys-lru automatically evicts the least recently used keys once the memory limit is reached — appropriate for cache-only use cases.

Enabling Persistence (If Needed)

By default Redis periodically snapshots to disk (RDB). For applications needing minimal data loss, enable append-only file persistence:

appendonly yes

Common Errors

"NOAUTH Authentication required" — a password is set; authenticate with AUTH your_password before other commands.

Redis won't start:

sudo journalctl -u redis-server

Best Practices

• Always set a password with requirepass, even for local-only access
• Keep bind 127.0.0.1 unless remote access is explicitly required and firewall-restricted
• Set maxmemory to prevent Redis from consuming all available RAM

FAQ

Does Redis replace my primary database?
No — Redis is typically used alongside a relational or document database to cache frequently accessed data and reduce load on the primary store.

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