Redis Installation and Setup (with Docker)

1. Introduction

In this lecture, we’ll learn how to install and set up Redis, understand what happens during installation, and how to interact with the Redis server using the Redis CLI.
We’ll also look at how to run Redis inside a Docker container, which is a very common and convenient setup for developers.

2. Installing Redis

When you install Redis, the installation process sets up two main components:

Redis Server (redis-server) – The main process that stores data in memory and handles all client requests.
Redis CLI (redis-cli) – A command-line interface used to interact with the Redis server.

Once installed, Redis runs a lightweight, in-memory database that can be accessed using the CLI or a programming language client library.

By default, the Redis server listens on port 6379, which is the standard Redis port.
Although you can change this in the configuration file, for now, we’ll keep it as 6379.

3. Redis Server Overview

When the Redis server (redis-server) is running:

It listens for client connections on port 6379.
It maintains all data in memory for fast access.
It supports multiple data structures such as Strings, Lists, Sets, Hashes, and Sorted Sets.

Redis does not use a declarative query language like SQL.
Instead, it uses an imperative command-based interface, where each operation is a direct command (for example, SET, GET, DEL, etc.).

You don’t have to memorize all the commands — Redis provides a comprehensive command reference and cheat sheet for quick lookup.

4. Interacting with Redis: The CLI (`redis-cli`)

The Redis CLI (redis-cli) is the simplest way to interact with a Redis server.
It allows you to issue commands directly to the server and see the results immediately.

For example:

SET name "James"
GET name

Output:

"James"

You can use it for learning, debugging, and administrative purposes.

If Redis is installed on your machine, you can start the server and CLI as follows:

Start Redis Server redis-server This launches the Redis server and begins listening on port 6379.
Connect using Redis CLI redis-cli Once connected, you can start issuing commands to interact with the running Redis instance.

If you see a message like:

127.0.0.1:6379>

it means your CLI is successfully connected to the Redis server.

5. Running Redis using Docker

If you don’t want to install Redis directly on your system, you can easily run it using Docker.
This is often the preferred method for development setups because it keeps your environment isolated and easy to manage.

Step 1: Create a `docker-compose.yml` file

Create a file named docker-compose.yml in a folder of your choice, and add the following content:

version: '3.8'
services:
  redis:
    image: redis:6.2
    container_name: redis
    ports:
      - "6379:6379"

Explanation:

image: Specifies the Redis image version to use (redis:6.2).
container_name: The name assigned to the container (here, redis).
ports: Maps Redis container port 6379 to host port 6379, allowing external clients to connect via localhost:6379.

Step 2: Start the container

In the same directory as your docker-compose.yml file, run:

docker-compose up -d

This command downloads the Redis image (if not already available) and runs the container in detached mode.

You can verify that Redis is running using:

docker ps

You should see a container named redis listening on port 6379.

6. Connecting to Redis CLI inside the Docker Container

Since Redis is running inside a Docker container, you need to access the CLI from within the container to interact with it.

Run the following command to open an interactive shell inside the Redis container:

docker exec -it redis bash

You are now inside the Redis container.
From here, you can launch the Redis CLI:

redis-cli

If everything is working correctly, you should see the Redis prompt:

127.0.0.1:6379>

This confirms that the CLI has successfully connected to the Redis server running inside Docker.

7. Testing the Redis Setup

Now that you have Redis and its CLI running, let’s test it with some simple commands.

SET language "Java"
GET language

Expected output:

"Java"

You can also try other operations:

INCR counter
INCR counter
GET counter

Output:

(integer) 1
(integer) 2
"2"

These commands verify that your Redis server is working correctly and storing data in memory.

8. Stopping the Redis Server

If you’re running Redis via Docker Compose, you can stop it at any time by running:

docker-compose down

This will gracefully shut down and remove the Redis container.

If you started it manually using docker run, you can stop it using:

docker stop redis

9. Summary

Let’s quickly recap what we covered in this session:

Redis installation includes both the server (redis-server) and the CLI (redis-cli).
By default, Redis listens on port 6379.
Redis uses imperative commands (not SQL) to manipulate data directly in memory.
You can easily run Redis in Docker using a simple docker-compose.yml file.
The CLI can be accessed inside the container using: docker exec -it redis bash redis-cli
Once connected, you can execute Redis commands to store and retrieve data instantly.

Redis is now up and running, and you’re ready to explore its data types, persistence options, and more advanced features in future lessons.