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How To Install and Configure Redis on CentOS 7

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 an 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:

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

    sudo yum install epel-release yum-utils
    sudo yum install http://rpms.remirepo.net/enterprise/remi-release-7.rpm
    sudo yum-config-manager --enable remi
  2. Install the Redis package by typing:

    sudo apt install redis
  3. Once the installation is completed, start the Redis service and enable it to start automatically on boot with:

    sudo systemctl start redis
    sudo systemctl enable 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 (local host) - 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

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
sudo firewall-cmd --zone=redis --add-port=6379/tcp --permanent
sudo firewall-cmd --zone=redis --add-source=192.168.121.0/24 --permanent
sudo firewall-cmd --reload

The commands above creates 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 setup 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.