How to Install Redis on a VPS

Redis is an in-memory data store used as a cache, session store, message broker, and rate limiter. It is blisteringly fast and pairs with almost any web app. This guide installs Redis on Ubuntu 24.04, secures it with a password, and configures sensible persistence.

Install Redis

Redis is in Ubuntu's default repositories:

sudo apt update
sudo apt install redis-server -y

The service starts automatically. Test it:

redis-cli ping

A reply of PONG means Redis is up.

Set Redis to run under systemd

Open /etc/redis/redis.conf and ensure Redis is supervised by systemd, which makes systemctl status reporting accurate:

supervised systemd

Set a password

By default Redis has no authentication. Anyone who can reach the port can read and flush your data — and exposed Redis instances are relentlessly attacked. In /etc/redis/redis.conf, set a strong password:

requirepass a-very-strong-redis-password

Restart to apply:

sudo systemctl restart redis-server

Now commands require auth:

redis-cli
127.0.0.1:6379> AUTH a-very-strong-redis-password
OK
127.0.0.1:6379> SET greeting "hello from Nxeon"
127.0.0.1:6379> GET greeting

Keep it bound to localhost

Confirm Redis is only listening locally — the default and the safe choice:

sudo ss -ltnp | grep 6379

You should see 127.0.0.1:6379. The bind 127.0.0.1 ::1 line in redis.conf controls this. If you ever need remote access, require the password, restrict port 6379 tightly in UFW, and prefer an SSH tunnel. Redis also has "protected mode" on by default, which refuses external connections without a password — leave it enabled.

Configure persistence

Redis holds data in RAM but can persist to disk so a restart does not wipe everything. Two mechanisms:

• RDB snapshots: periodic point-in-time dumps. The default save rules (e.g. save 900 1) already enable this.
• AOF (append-only file): logs every write for stronger durability. Enable it in redis.conf:

appendonly yes
appendfsync everysec

appendfsync everysec is the sweet spot — at most one second of data loss on a crash, with negligible performance cost. Restart after changing it. If you use Redis purely as a disposable cache, you can leave persistence off for maximum speed.

Set a memory limit

To stop Redis consuming all RAM on a small VPS, cap it and pick an eviction policy in redis.conf:

maxmemory 256mb
maxmemory-policy allkeys-lru

allkeys-lru evicts the least-recently-used keys when full — ideal for a cache. For a session store where you must not lose keys, use noeviction and size memory accordingly.

Connect from your app

Most frameworks take a URL like redis://:password@127.0.0.1:6379/0. In a Node app with ioredis or redis, point it there; in Django or Flask, use it for the cache and session backend. This pairs naturally with a Node app under PM2 or a Flask app behind Gunicorn.

Common Redis patterns

Redis is far more than a key-value cache. A few patterns you will use constantly, all from redis-cli:

Caching with expiry — store a value that self-deletes after a time, ideal for API responses or rendered pages:

SET user:42:profile "{...}" EX 3600

Rate limiting — count actions per window using atomic increments:

INCR ratelimit:1.2.3.4
EXPIRE ratelimit:1.2.3.4 60

Simple queues — push jobs onto a list and pop them from a worker:

LPUSH jobs "send-email:42"
RPOP jobs

Sessions — store a session hash keyed by token with an expiry so idle sessions clean themselves up.

Inspect and monitor

Two commands help day to day: redis-cli INFO reports memory, hit rate, and connections, and redis-cli --stat shows a live one-line dashboard. Watch the keyspace hit ratio — a low ratio means your cache is not helping and keys may be expiring too quickly.

FAQ

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