Keepalived active stand by

On master site ip 10.7.168.221, file /etc/keepalived/keepalived.conf. All config in /etc/keepalived can be found here​

root@n4:/etc/keepalived# pwd
/etc/keepalived
root@n4:/etc/keepalived# more keepalived.conf 
vrrp_script chk_service_health {
    #script /etc/keepalived/check_proc.sh
    #script /etc/keepalived/check_ping.sh
    weight 10
    # how often script run in period 10 sec
    interval 5
    # How long to wait for the script to return (5 seconds).
    timeout 5
    # How many times the script must return successfully in order for the host to be considered healthy.
    rise 3
    # How many times the script must return unsuccessfully (or time out) in order for the host to be considered unhealthy
    fall 3
}

vrrp_instance VI_1 {
        #state BACKUP
        state MASTER
        interface ens3
        virtual_router_id 51
        priority 201
        advert_int 10
        authentication {
              auth_type PASS
              auth_pass 1234
        }
        unicast_src_ip 10.7.168.221
        unicast_peer {
             10.7.168.58
        }
        virtual_ipaddress {
             10.7.168.200/24
        }
        track_script {
            chk_service_health
        }
        notify /etc/keepalived/keepalived_notify.sh
        notify_master /etc/keepalived/keepalived_notify_master.sh
        notify_backup /etc/keepalived/keepalived_notify_backup.sh
}

At user directory /home/ubuntu, pls see files check_containner.sh​, notifyFile_3.sh​, stop_notifyFile_3.sh​ use for start/stop docker. For sync with unison, we need to place file default.prf​ in ./unison/default.prf user folder /home/ubuntu/.unison. Pls note, unison need to use ssh-keygen to authentication and place in user as /home/ubuntu/.ssh/authorized_keys.

ubuntu@n4:~$ tree -L 2
├── check_containner.sh
├── default.prf
├── notifyFile_3.sh
├── nodedb1_start.sh
├── omd-labs-docker
│   ├── Dockerfile.omd-labs-debian
│   ├── Makefile.omd-labs-debian
│   ├── README.md
│   ├── ansible_dropin
│   ├── hooks
│   ├── run.sh
│   ├── scripts
│   └── site
└── stop_notifyFile_3.sh

After wake up, we need to start docker database and sync to mysql group replication. In command docker exec -i, we use only -i not -it because -t was a tty console when run as a script it was not from tty console so we need to use only -i (interactive mode) ref​here. This file was in nodedb1_start.sh​ where the keepalived_notify_master.sh should call this file.

#!/usr/bin/bash

logfile=/tmp/nodedb1.log
container_name=nodedb1
/usr/bin/docker start $container_name
echo "docker start $container_name" >> $logfile
sleep 10
if [ "$( docker container inspect -f '{{.State.Status}}' $container_name )" == "running" ]; then 
   echo "$container_name is running" >> $logfile
else
   echo "$container_name is not running, we will start again" >> $logfile
   /usr/bin/docker start $container_name
   echo "start $container_name Done!!" >> $logfile
fi

if [ "$( docker container inspect -f '{{.State.Status}}' $container_name )" == "running" ]; then
   cmd1="/usr/bin/docker exec -i $container_name mysql -uroot -pmypass -e \"STOP GROUP_REPLICATION;\" \
                      -e \"SET @@GLOBAL.group_replication_group_name='aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee';\" \
                      -e \"SET @@GLOBAL.group_replication_local_address='$container_name:33061';\"\
                      -e \"SET @@GLOBAL.group_replication_group_seeds='$container_name:33061,nodedb2:33061,nodedb3:33061';\" \
                      -e \"change master to master_user='repl' for channel 'group_replication_recovery';\" \
                      -e \"START GROUP_REPLICATION;\"  " 
   echo "$cmd1" >> $logfile
   eval "$cmd1" 2> /tmp/err.log 1>> $logfile
   sleep 10
   echo "$container_name join group_replication" >> $logfile
   cmd2="/usr/bin/docker exec -i $container_name mysql -uroot -pmypass -e \"SELECT * FROM performance_schema.replication_group_members;\" "
   echo "$cmd2" >> $logfile
   # we need " double quote around "$cmd2" because * wildcard will not process as * in Linux command
   # eval $cmd2 not work we must use 
   # eval "$cmd2" 
   eval "$cmd2" 2> /tmp/err.log 1>> $logfile
else
   echo "$container_name still not start" >> $logfile 
fi

For standby site (backup site ip 10.7.168.58) config can be found here​

---

keepalived Backup site check DB Group Replicate

#!/usr/bin/bash
logfile=/tmp/keepalived.log
echo "Time: $(date). keepalive log -------" >> $logfile 

IP_MASTER="192.168.81.12"
STR_CHECK="ONLINE"

#/usr/bin/unison > /dev/null 2>&1
/bin/ping -c 2 -W 1 192.168.81.12 > /dev/null 2>&1
status=$?
echo 'ping ' $status
if [ $status -eq 0 ]
then
   all_result=`/usr/bin/docker exec -i nodedb1 mysql -uroot -pmypass -e 'SELECT * FROM performance_schema.replication_group_members;'`
   online=$(echo $all_result | grep "$IP_MASTER" | awk '{ print $12}' )
   if [[ "$online" == *"$STR_CHECK"* ]]
   then
       echo "Master node OK" >> $logfile
       exit 1 # All good. DB master reachable
   else
       echo "Master node Fail" >> $logfile
       exit 0 # Failover trigger
   fi
else
   echo "Master node Fail" >> $logfile
   exit 0 # Failover trigger
fi