What Is Redis And How To Install It ?

What Is Redis ?

Redis is an BSD licensed, open source, advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs. Refer redis.io/topics/introduction to know more about Redis.

We will learn how to install redis on a CentOS cPanel server. On a CentOS cPanel server, we will need to install redis daemon & the redis PHP extension. Once installed & enabled it helps in boosting the eCommerce website performance.

Install Redis Daemon

cd /usr/local/
wget http://download.redis.io/releases/redis-2.8.12.tar.gz
tar -xvzf redis-2.8.12.tar.gz
cd redis-2.8.12
make
cp src/redis-server /usr/local/bin
cp src/redis-cli /usr/local/bin
mkdir -p /etc/redis
mkdir -p /var/redis
cp redis.conf /etc/redis/redis.conf

Now, let’s edit /etc/redis/redis.conf & configure it to work with the server. Set the values as below.

daemonize yes
port 6379
bind 127.0.0.1
dir /var/redis/
logfile /var/log/redis.log
pidfile /var/run/redis.pid

We will now need a startup script which will start, stop, restart redis on your server. Create a file /etc/init.d/redis & add below content. Set permissions to 755 so that the file is executable.

#!/bin/sh
#
# redis – this script starts and stops the redis-server daemon
#
# chkconfig: – 85 15
# description: Redis is a persistent key-value database
# processname: redis-server
# config: /etc/redis/redis.conf
# config: /etc/sysconfig/redis
# pidfile: /var/run/redis.pid

# Source function library.
. /etc/rc.d/init.d/functions

# Source networking configuration.
. /etc/sysconfig/network

# Check that networking is up.
[ “$NETWORKING” = “no” ] && exit 0

redis=”/usr/local/bin/redis-server”
prog=$(basename $redis)

REDIS_CONF_FILE=”/etc/redis/redis.conf”

[ -f /etc/sysconfig/redis ] && . /etc/sysconfig/redis

lockfile=/var/lock/subsys/redis

start() {
[ -x $redis ] || exit 5
[ -f $REDIS_CONF_FILE ] || exit 6
echo -n $”Starting $prog: ”
daemon $redis $REDIS_CONF_FILE
retval=$?
echo
[ $retval -eq 0 ] && touch $lockfile
return $retval
}

stop() {
echo -n $”Stopping $prog: ”
killproc $prog -QUIT
retval=$?
echo
[ $retval -eq 0 ] && rm -f $lockfile
return $retval
}

restart() {
stop
start
}

reload() {
echo -n $”Reloading $prog: ”
killproc $redis -HUP
RETVAL=$?
echo
}

force_reload() {
restart
}

rh_status() {
status $prog
}

rh_status_q() {
rh_status >/dev/null 2>&1
}

case “$1″ in
start)
rh_status_q && exit 0
$1
;;
stop)
rh_status_q || exit 0
$1
;;
restart|configtest)
$1
;;
reload)
rh_status_q || exit 7
$1
;;
force-reload)
force_reload
;;
status)
rh_status
;;
condrestart|try-restart)
rh_status_q || exit 0
;;
*)
echo $”Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload}”
exit 2
esac

Update the system services & configure redis daemon to start after server reboot.

chkconfig –add redis
chkconfig redis on

Start the redis service with command below. You can use command redis-cli ping to check if it works properly. If you get a result PONG it means redis is working.

/etc/init.d/redis start

To know more about the command and it’s options use redis-cli –help.

Install Redis PHP Extension

Redis PHP extension is installed by performing couple of commands.

pecl install redis

Open the server’s php.ini file & add extension=redis.so to it. You can get the server’s php.ini file with command php -i | grep php.ini. Restart apache (your web server) & you are done