Running multiple Redis instances on the same server.

Setting up multiple Redis instances on the same server is pretty easy, but if you want to be able to easily start/stop and restart instances, you’ll need to play with the init scripts of redis-server.

I needed this to be able to offer Redis buckets to different customers on a shared platform.

This is how I managed to set up multiple instances on the same server.
Since installing redis-server is out of the scope of this article, I’ll only explain what I did to manage multiple Redis Servers.

* Setting up a new INIT script:

cd /etc/init.d
mv redis-server ~/redis-server.bak
touch redis-server
chmod 755 redis-server
vim redis-server

* Paste this into the new redis-server init script:

#!/bin/sh
### BEGIN INIT INFO
# Provides:             redis-server
# Required-Start:       $syslog $remote_fs
# Required-Stop:        $syslog $remote_fs
# Should-Start:         $local_fs
# Should-Stop:          $local_fs
# Default-Start:        2 3 4 5
# Default-Stop:         0 1 6
# Short-Description:    redis-server - Persistent key-value db
# Description:          redis-server - Persistent key-value db
### END INIT INFO

if [ "$#" -eq 2 ]
then
NAME=$2

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DAEMON=/usr/bin/redis-server
DAEMON_ARGS=/etc/redis/servers/$NAME.conf
DESC=redis-server

RUNDIR=/var/run/redis
PIDFILE=$RUNDIR/$NAME.pid

echo "Managing Redis server with the following attributes:"
echo "   Daemon Args: $DAEMON_ARGS"
echo "   Pidfile: $PIDFILE"

test -x $DAEMON || exit 0

#if [ -r /etc/default/$NAME ]
#then
#       . /etc/default/$NAME
#fi

. /lib/lsb/init-functions

set -e

case "$1" in
  start)
        echo -n "Starting $DESC: "
        mkdir -p $RUNDIR
        touch $PIDFILE
        chown redis:redis $RUNDIR $PIDFILE
        chmod 755 $RUNDIR

        if [ -n "$ULIMIT" ]
        then
                ulimit -n $ULIMIT
        fi

        if start-stop-daemon --start --quiet --umask 007 --pidfile $PIDFILE --chuid redis:redis --exec $DAEMON -- $DAEMON_ARGS
        then
                echo "$NAME."
        else
                echo "failed"
        fi
        ;;
  stop)
        echo -n "Stopping $DESC: "
        if start-stop-daemon --stop --retry forever/QUIT/1  --oknodo --pidfile $PIDFILE --exec $DAEMON -- $DAEMON_ARGS
        then
                echo "$NAME."
        else
                echo "failed"
        fi
        rm -f $PIDFILE
        sleep 1
        ;;

  restart|force-reload)
        ${0} stop $2
        ${0} start $2
        ;;

  status)
        echo -n "$DESC is "
        if start-stop-daemon --stop --quiet --signal 0 --name ${NAME} --pidfile ${PIDFILE}
        then
                echo "running"
        else
                echo "not running"
                exit 1
        fi
        ;;

  *)
        echo "Usage: /etc/init.d/redis-server/$NAME {start|stop|restart|force-reload|status}" >&2
        exit 1
        ;;
esac

else
FILES=/etc/redis/servers/*
for f in $FILES
do
  echo $f
  SERVERNAME=`echo ${f##*/}`
  SERVERNAME=${SERVERNAME%.conf}
  /etc/init.d/redis-server "$1" "$SERVERNAME"
done
fi

exit 0

Once that is done, we need to add multiple config files for our different buckets:

mkdir /etc/redis/servers
cd /etc/redis/servers
vim www.nicovs.be.conf

And enter some config settings looking like this:

#Include the default redis settings
include /etc/redis/redis.conf

#Only enable 1 Database for this instance, not the default 16 (or change the default in /etc/redis/redis.conf to 1
databases 1

#Max amount of RAM this instance can use:
maxmemory 100mb

#If no TTL is being set by the application using this instance, this policy will evict all keys by an approximated LRU algorithm as long as we hit the memory limit.
maxmemory-policy allkeys-lru

#Placeholder to be able to save the DB to an rdb dump file.
#save 900 1
#save 300 10
#save 60 10000

#Pidfile
pidfile /var/run/redis/www.nicovs.be.pid
#Which Port to use for this instance
port 5033
#Where to log the output of this instance
logfile /var/log/redis/www.nicovs.be.log

# The RDB Dump base dir
dir /backups/redis
#The RDP Dump filename
dbfilename www.nicovs.be.rdb

## Security settings:
# Disable the config command, so that customers are not able to change the server config from command line.
rename-command CONFIG ""

requirepass aVery_Long_!1290-PasSwooo00Ord_ToProtectBruteForce

Creating new instances is easily done by copying this initial conf file and adjusting the params (port, name, pid, savefilename, password,…)

Now, if you want to start/stop or restart all redis instances at the same time, this can be done with the normal service command:

service redis-server start
service redis-server stop
service redis-server restart
service redis-server status

The new init script we create above, will simply index all config instances from /etc/redis/servers and manage those 1 at a time.

Or, if you only want to manage 1 instance at a time, just do something like this for example:

service redis-server restart www.nicovs.be

which will restart only the instance running for website www.nicovs.be

Since we use this on a shared environment, we have a provisioning system in place, where our customers can change some settings

This article is based on: Robofirm: Setting up multiple redis instances, but I had to change some configuration to make it work. Anyway, a big thanks to Kirk Madera for pointing me in the right direction!