How to Set Up Redis on CentOS 7

In this tutorial, we are going to build and install Redis on our CentOS 7 Cloud VPS from source.

Redis is an in-memory data structure store primarily used as a database and cache. Redis supports different kinds of abstract data structures such as strings, lists, maps, sets, sorted sets, hyper logs, bitmaps, and spatial indexes. The Redis package that is included in the default CentOS repositories is pretty outdated, so installing from the source code will ensure that we have the latest version of Redis installed on our system. Let’s begin with the installation.

Step 1. Install Dependencies

Connect to your CentOS server via SSH and upgrade the installed packages to the newest versions by typing:

yum update

Install the pre-requisite packages necessary for building Redis using the following yum command:

yum install gcc make wget tcl

Once the packages are installed, you can move on to the next step.

Step 2. Install Redis 5.0 on CentOS 7

At the time of writing this article, the latest stable version of Redis was 5.0.0.

The installation process is quite an easy task, start by navigating to the /usr/local/src/ directory:

cd /usr/local/src

Download the Redis archive by running the following wget command:

wget http://download.redis.io/releases/redis-5.0.0.tar.gz

Once the download has completed, extract the downloaded file with the following tar command:

tar xf redis-5.0.0.tar.gz

Navigate to the Redis source directory:

cd redis-5.0.0

Start the compilation process using the make command:

make

The build process may take some time depending on your server resources, once completed the following message will be printed on your screen:

Hint: It's a good idea to run 'make test' ;)

make[1]: Leaving directory `/usr/local/src/redis-5.0.0/src'

Now, run the make test command to make sure everything was built correctly:

make test

The next step is to install Redis binaries using the make install command:

 make install

Redis has been successfully installed. Now, let’s configure it.

Step 3. Creating a Redis User

The following commands will create a group and user named “redis”:

groupadd redis
adduser --system -g redis --no-create-home redis

Next create the /var/lib/redis directory which will store the redis databases:

mkdir -p /var/lib/redis

Give the redis user and group ownership over the directory:

chown redis: /var/lib/redis

Set the correct permissions with:

chmod 770 /var/lib/redis

Step 4. Creating Redis Configuration

Now that Redis is installed and intial setup has been completed on your CentOS 7 VPS, you’ll need to create the configuration file.

First, create the /etc/redis directory with:

mkdir /etc/redis

Next copy the default configuration file by running:

cp /usr/local/src/redis-5.0.0/redis.conf /etc/redis/

Open the file with your preferred text editor (we’ll be using nano):

nano /etc/redis/redis.conf

Search for the supervised directive and change it to “systemd”:

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
#   supervised no      - no supervision interaction
#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
#   supervised auto    - detect upstart or systemd method based on
#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
#       They do not enable continuous liveness pings back to your supervisor.

supervised systemd

Search for the dir directive and set it to /var/lib/redis:

# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir /var/lib/redis

Once done, save and close the file.

Step 5. Creating a Redis Systemd Unit File

Now that Redis is installed and configured, the last step is to create a systemd unit file so that you can manage the Redis servis as a regular systemd service.

Open your text editor and create the follwing file:

nano /etc/systemd/system/redis.service

Then add the following content to it:

[Unit]
Description=Redis Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/local/bin/redis-server /etc/redis/redis.conf
ExecStop=/usr/local/bin/redis-cli shutdown
Restart=always

[Install]
WantedBy=multi-user.target

Save and close the file. Enable and start the Redis service with:

systemctl enable redis
systemctl start redis

To check that the Redis service has no errors, run:

systemctl status redis

The output should look like this:

● redis.service - Redis Data Store
   Loaded: loaded (/etc/systemd/system/redis.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2018-11-12 04:39:32 CST; 5s ago
 Main PID: 9788 (redis-server)
   CGroup: /system.slice/redis.service
           └─9788 /usr/local/bin/redis-server 127.0.0.1:6379

Finally, to verify that the Redis service is functioning correctly, run the following command:

redis-cli PING

The output should look like:

PING

And that’s it! You now have a working Redis instance that’s configured and ready to be used. Reading the Redis documentation is a good way to start learning how Redis works, as well as how to configure it more in-depth for your specific application.

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