How to Install and Configure Redis on Linux Servers -

What is Redis? #

Redis (Remote Dictionary Server) is an open-source, in-memory data structure store that can be used as a database, cache, and message broker. Known for its high performance, Redis supports data structures like strings, hashes, lists, sets, and more. It’s often used for applications requiring fast data retrieval, caching, real-time analytics, and session management.

Prerequisites #

Before installing Redis, ensure that:

You have a Linux server – Redis can be installed on distributions like Ubuntu, Debian, CentOS, and RHEL.
Your server is updated – Run system updates to ensure all packages are current.
Basic command-line knowledge – Familiarity with Linux commands will be helpful.

Step 1: Update the Package Repository #

Update your system’s package list to make sure you have access to the latest version of Redis:

For Ubuntu/Debian #

sudo apt update

For CentOS/RHEL #

sudo yum update

Step 2: Install Redis #

Redis is available through the default repositories on most Linux distributions, so you can install it directly using your package manager.

On Ubuntu/Debian: #

sudo apt install redis-server -y

On CentOS/RHEL: #

Install EPEL Repository (if not already installed):

sudo yum install epel-release -y

2. Install Redis:

sudo yum install redis -y

Step 3: Configure Redis #

The main configuration file for Redis is usually located at /etc/redis/redis.conf on Debian-based systems or /etc/redis.conf on Red Hat-based systems. Here are some common configurations you may want to adjust:

Enable Persistence: Redis stores data in memory, but you can enable data persistence to save it to disk.

Open the configuration file:

sudo vi /etc/redis/redis.conf

Locate the appendonly setting and set it to yes:

appendonly yes

2. Set up a Password: For security, set a password to protect your Redis instance.

In the redis.conf file, locate requirepass and set a strong password:

requirepass YourStrongPassword

3. Configure Network Binding: By default, Redis binds to localhost. To allow access from other hosts, modify the bind setting in the configuration file:

bind 0.0.0.0

Note: Enabling remote access requires strong security measures, such as firewalls and passwords.

4. Set a Memory Limit: Redis allows you to define a maximum memory usage, which can be helpful if you’re using it as a cache

Set the memory limit by adding or updating the following lines in the configuration file:

maxmemory 256mb
maxmemory-policy allkeys-lru

5. Define Save Intervals: Redis can periodically save data to disk based on specific intervals.

You can set save intervals in the configuration file like this:

save 900 1
save 300 10
save 60 10000

Step 4: Start and Enable Redis #

Once configured, start the Redis service and enable it to start at boot:

sudo systemctl start redis

sudo systemctl enable redis

To verify that Redis is running:

sudo systemctl status redis

Step 5: Testing Redis #

Connect to Redis CLI: Use the Redis CLI to connect to the Redis server.

redis-cli

2. Authenticate (if you set a password):

AUTH YourStrongPassword

3. Ping the Server: Test the connection by running:

ping

Step 6: Enable Redis for External Access (Optional) #

If you plan to access Redis from outside the server (e.g., for use with a web application hosted elsewhere), ensure the Redis port (6379) is open in your firewall:

# For UFW (on Ubuntu)
sudo ufw allow 6379

# For firewalld (on CentOS/RHEL)
sudo firewall-cmd --permanent --add-port=6379/tcp
sudo firewall-cmd --reload

Warning: Allowing external access to Redis without proper security settings is risky. Always use strong passwords, configure firewalls, or set up a VPN for secure access.

Step 7: Verify the Installation #

You can access Redis from your local or remote setup by running:

redis-cli -h -p 6379

Final Word #

Redis is now installed and configured on your Linux server. You’ve set up basic security, enabled persistence, and adjusted network and memory settings for optimal performance.