linux-rhel7-run-multiple-redis-instances.md

#FOR MULTIPLE REDIS INSTANCE INSTALLATION ON RHEL7+ USE THE FOLLOWING PATHS AND SETUP PROCESS:

• create a new redis .conf file

$ cp /etc/redis.conf /etc/redis-xxx.conf

• edit /etc/redis-xxx.conf, illustrated as below

...
#modify pidfile
#pidfile /var/run/redis/redis.pid
pidfile /var/run/redis/redis-xxx.pid

...
#dir /var/lib/redis/
dir /var/lib/redis-xxx/

...
#modify port
#port 6379
port 6380

...
#modify logfile
#logfile /var/log/redis/redis.log
logfile /var/log/redis/redis-xxx.log

...
#modify vm-swap-file
#vm-swap-file /tmp/redis.swap
vm-swap-file /tmp/redis-xxx.swap
...

• make dir /var/lib/redis-xxx

$ mkdir -p /var/lib/redis-xxx

• THERE IS NO init.d files RHEL uses systemctl instead so:
• copy existing service over to your new service

$ cp /usr/lib/systemd/system/redis.service /usr/lib/systemd/system/redis-xxx.service

• modify your new service script to the following: (just change the redis-xxx path)

...

#[Unit]
Description=Redis persistent key-value database
After=network.target

#[Service]
ExecStart=/usr/bin/redis-server /etc/redis-xxx.conf --daemonize no
ExecStop=/usr/bin/redis-shutdown
User=redis
Group=redis

#[Install]
WantedBy=multi-user.target
...

• if you have sentinel enabled on your system you will need to: (otherwise skip this step)

# Copy values from cat /usr/lib/systemd/system/redis.service to /usr/lib/systemd/system/redis-xxx.service
$ cp /usr/lib/systemd/system/redis.service /usr/lib/systemd/system/redis-xxx.service

• then edit the contents of /usr/lib/systemd/system/redis-xxx.service (just change the /etc/redis-xxx path again)

• start the new services:

$ service redis-xxx start

• check the new services status:

$ service redis-xxx status

• stop the new services status:

$ service redis-xxx stop

• restart the new services status:

$ service redis-xxx restart

• if you get some problems with service not found:
• you can do the following:

$ systemctl unmask packagekit.service
$ systemctl mask packagekit.service

• then try to start the service again

Hey,
Using this configuration I was having an issue when restarting a service i.e
sudo systemctl restart redis-fpc
Would restart redis-fpc as intended, but due to redis-shutdown lacking first argument would also bring down the primary redis running on 6379.
To resolve this the custom Redis systemd script must be updated as follows
ExecStop=/usr/bin/redis-shutdown redis-fpc instead of ExecStop=/usr/bin/redis-shutdown

The content below shows how redis-shutdown acts on RHEL 7.3 and explains the behavior I mentioned above.

#!/bin/bash
#
# Wrapper to close properly redis and sentinel
test x"$REDIS_DEBUG" != x && set -x

REDIS_CLI=/usr/bin/redis-cli

# Retrieve service name
SERVICE_NAME="$1"
if [ -z "$SERVICE_NAME" ]; then
   SERVICE_NAME=redis
fi

# Get the proper config file based on service name
CONFIG_FILE="/etc/$SERVICE_NAME.conf"

# Use awk to retrieve host, port from config file
HOST=`awk '/^[[:blank:]]*bind/ { print $2 }' $CONFIG_FILE`
PORT=`awk '/^[[:blank:]]*port/ { print $2 }' $CONFIG_FILE`

# Just in case, use default host, port
HOST=${HOST:-127.0.0.1}
if [ "$SERVICE_NAME" = redis ]; then
    PORT=${PORT:-6379}
else
    PORT=${PORT:-26739}
fi

# shutdown the service properly
$REDIS_CLI -h $HOST -p $PORT shutdown

I am trying this on an ec2 amazon ami with no systemctl also redis-shutdown is at /usr/libexec/ and this doesnt work: ExecStop=/usr/libexec/redis-shutdown redis_6379

Instead I have created multiple copies of redis-shutdown, redis-server and init files for each instance.
so I have

/etc/init.d/redis_6379 /etc/init.d/redis_6380 and /etc/init.d/redis_6381
/usr/bin/redis_6379 /usr/bin/redis_6380 and /usr/bin/redis_6381  (instead of /usr/bin/redis-server)
/usr/libexec/redis_6379-shutdown /usr/libexec/redis_6380-shutdown and /usr/libexec/redis_6381-shutdown (instead of /usr/libexec/redis-shutdown

This line in each shutdown file points to each init file. SERVICE_NAME=redis_6379 Its working fine with 3 instances right now with ports 6379, 80. 81. no errors on start and stop. Only thing i need some explanation is these lines in the default shutdown file:

if [ "$SERVICE_NAME" = **redis** ]; then
    PORT=${PORT:-**6379**}
else
    PORT=${PORT:-**26739**}

whats the 26739 port for ?
I have currently used following config for each of the shut down file
example: /usr/libexec/redis_6380-shutdown

if [ "$SERVICE_NAME" = **redis_6380** ]; then
    PORT=${PORT:-**6380**}
else
    PORT=${PORT:-**26740**}

Is there an easier alternative to this??