Redis is an open-source in-memory data structure store. It can be  used as a database, cache and message broker and supports various data  structures such as Strings, Hashes, Lists, Sets, etc. Redis provides  high availability via Redis Sentinel including monitoring, notifications  Automatic failover. It also provides automatic partitioning across  multiple Redis nodes with Redis Cluster.

This tutorial explains how to install and configure Redis on a CentOS 7 server.

Prerequisites

Before starting with the tutorial, make sure you are logged in as a user with sudo privileges.

Installing Redis on CentOS 7

Redis  package is not included in the default CentOS repositories. We will be  installing Redis version 5.0.2 from the Remi repository.

The installation is pretty straightforward, just follow the steps below:

Start by enabling the Remi repository by running the following commands in your SSH terminal:

sudo yum install epel-release yum-utils

Install the Redis package by typing:

sudo yum install redis

Once the installation is completed, start the Redis service and enable it to start automatically on boot with:

sudo systemctl start redis
Created symlink from /etc/systemd/system/multi-user.target.wants/redis.service to /usr/lib/systemd/system/redis.service.

To check the status of the service enter the following command:

sudo systemctl status redis

You should see something like the following:

● redis.service - Redis persistent key-value database
Loaded: loaded (/usr/lib/systemd/system/redis.service; enabled; vendor preset: disabled)
Drop-In: /etc/systemd/system/redis.service.d
        └─limit.conf
Active: active (running) since Sat 2018-11-24 15:21:55 PST; 40s ago
Main PID: 2157 (redis-server)
CGroup: /system.slice/redis.service
        └─2157 /usr/bin/redis-server 127.0.0.1:6379

Redis service will fail to start if IPv6 is disabled on your server.

Congratulations, at this point you have Redis installed and running on your CentOS 7 server.

Configure Redis Remote Access

By  default, Redis doesn’t allow remote connections. You can connect to the  Redis server only from 127.0.0.1 (localhost) - the machine where Redis  is running.

Perform  the following steps only if you want to connect to your Redis server  from remote hosts. If you are using a single server setup, where the  application and Redis are running on the same machine then you should  not enable remote access.

To configure Redis to accept remote connections open the Redis configuration file with your text editor:

sudo nano /etc/redis.conf

Locate the line that begins with bind 127.0.0.1 and add your server private IP address after 127.0.0.1.

/etc/redis.conf

# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bind 127.0.0.1 192.168.121.233

Copy

Make sure you replace 192.168.121.233 with your IP address. Save the file and close the editor.

Restart the Redis service for changes to take effect:

sudo systemctl restart redis

Use the following ss command to verify that the Redis server is listening on your private interface on port 6379:

ss -an | grep 6379

You should see something like below:

tcp    LISTEN     0      128    192.168.121.233:6379            *:*
tcp    LISTEN     0      128    127.0.0.1:6379                  *:*

Next, you’ll need to add a firewall rule that enables traffic from your remote machines on TCP port 6379.

Assuming you are using FirewallD to manage your firewall and you want to allow access from the 192.168.121.0/24 subnet you would run the following commands:

sudo firewall-cmd --new-zone=redis --permanent

The commands above create a new zone named redis, opens the port 6379 and allows access from the private network.

At this point, Redis server will accept remote connections on TCP port 6379.

Make sure your firewall is configured to accept connections only from trusted IP ranges.

To verify that everything is set up properly, you can try to ping the Redis server from your remote machine using the redis-cli utility which provides a command-line interface to a Redis server:

redis-cli -h <REDIS_IP_ADDRESS> ping

The command should return a response of PONG:

PONG

Conclusion

Congratulations, you  have successfully installed Redis on your CentOS 7 server. To learn  more about how to use Redis, visit their official documentation page.

If you have questions, feel free to leave a comment below.