Redis Master and Slave usage

Solution 1:

At the server side, for a simple failover, you can do it by using Nagios and NRPE.

On the Nagios server:

define service{
    use                     critical-service
    host_name               B
    service_description     redis:2302
    check_command           check_tcp!2302
    event_handler           promote_redis!C!2302
    contact_groups          admin-sms,admin

}

define command{ 
    command_name    promote_redis
    command_line    $USER1$/eventhandlers/promote_redis.sh $SERVICESTATE$ $SERVICESTATETYPE$ $SERVICEATTEMPT$ $ARG1$ $ARG2$
}

promote_redis.sh

#!/bin/bash

case "$1" in
    OK)
        ;;
    WARNING)
        ;;
    UNKNOWN)
        /usr/local/nagios/libexec/check_nrpe -H $4 -c promote_redis -a $5
        ;;
    CRITICAL)
        /usr/local/nagios/libexec/check_nrpe -H $4 -c promote_redis -a $5
        ;;
esac

exit 0

On the slave:

nrpe.cfg

command[promote_slave_redis]=/usr/lib64/nagios/plugins/promote_redis.sh $ARG1$

promote_redis.sh

#!/bin/bash

echo 'slaveof no one' | /usr/local/redis/bin/redis-cli -h C -p $1

Virtual IP can be set up by using keepalived, something like this:

/etc/keepalived/keepalived.conf

vrrp_script chk_redis {
    script "killall -0 redis-server"
    interval 2
    weight 2
}

vrrp_instance VI_1 {
    state MASTER
    #nopreempt
    interface eth0
    lvs_sync_daemon_interface eth0
    virtual_router_id 51
    priority 101
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass pa$$w0rd
    }
    virtual_ipaddress {
        x.y.z.t
    }
    track_script {
        chk_redis
    }
}

But what happens if you want to run multiple instances?

Yves Trudeau and Percona wrote a great resource agent to failover MySQL. Based on that, Martin Walter rewrite for the Redis service. Give it a try!

crm configure show

node master_629
node svr200-632.localdomain
primitive VIP ocf:heartbeat:IPaddr2 \
    params ip="192.168.6.179" cidr_netmask="24" \
    meta target-role="Started"
primitive redis_6380 ocf:heartbeat:redis \
    params config="/usr/local/redis/etc/redis.conf"
ms ms_redis_6380 redis_6380 \
    meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true" target-role="Started"
location REDIS-PREFER-master_629 ms_redis_12345 100: master_629
colocation vip_on_ms_redis_6380 inf: VIP:Started ms_redis_6380:Master
order vip_after_ms_redis_6380 inf: ms_redis_6380:promote VIP:start
property $id="cib-bootstrap-options" \
    no-quorum-policy="ignore" \
    default-action-timeout="60s" \
    stonith-enabled="false" \
    startup-fencing="false" \
    dc-version="1.0.12-unknown" \
    cluster-infrastructure="openais" \
    expected-quorum-votes="2"

crm status

============
Last updated: Tue Aug 21 22:12:11 2012
Stack: openais
Current DC: master_629 - partition with quorum
Version: 1.0.12-unknown
2 Nodes configured, 2 expected votes
6 Resources configured.
============

Online: [ svr200-632.localdomain master_629 ]

 Master/Slave Set: ms_redis_12345
     Masters: [ master_629 ]
     Slaves: [ svr200-632.localdomain ]
 VIP    (ocf::heartbeat:IPaddr2):   Started master_629
 Master/Slave Set: ms_redis_6380
     Masters: [ master_629 ]
     Slaves: [ svr200-632.localdomain ]

Solution 2:

You either handle it in the client or use something like

https://github.com/sreeix/redis-proxy

Redis Master and Slave usage

Solution 1:

Solution 2:

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