Master-master replication example

Detailed description of this example configuration could be found in “Typical use-cases of mmm-deployment” document.

Let’s take a looks on example configuration files for such configuration. Every deployment of mmm requires N+1 installation where N is number of MySQL servers and 1 is monitoring server (can be combined with application server). Following examples would be named as mmm_mon.conf for minitoring server and mmm_agent.conf for database servers.

mmm_mon.conf is following:

#
# Master-Master Manager config (monitor)
#

# Debug mode
debug no

# Paths
pid_path /opt/mmm/var/mmmd.pid
status_path /opt/mmm/var/mmmd.status
bin_path /opt/mmm/bin

# Logging setup
log mydebug
    file /opt/mmm/var/mmm-debug.log
    level debug

log mytraps
    file /opt/mmm/var/mmm-traps.log
    level trap


# MMMD command socket tcp-port
bind_port 9988
agent_port 9989
monitor_ip 127.0.0.1

# Cluster interface
cluster_interface eth0

# Cluster hosts addresses and access params
host master1
    ip 192.168.1.8
    port 3306
    user rep_monitor
    password RepMonitor
    mode master
    peer master2

host master2
    ip 192.168.1.9
    port 3306
    user rep_monitor
    password RepMonitor
    mode master
    peer master1

#
# Define roles
#

active_master_role writer

# Mysql Reader role
role reader
    mode balanced
    servers master1, master2
    ip 192.168.1.100, 192.168.1.101

# Mysql Writer role
role writer
    mode exclusive
    servers master1, master2
    ip 192.168.1.200, 192.168.1.201

#
# Checks parameters
#

# Ping checker
check ping
    check_period 1
    trap_period 5
    timeout 2

# Mysql checker
check mysql
    check_period 1
    trap_period  2
    timeout 2

# Mysql replication backlog checker
check rep_backlog
    check_period 5
    trap_period 10
    max_backlog 60
    timeout 2

# Mysql replication threads checker
check rep_threads
    check_period 1
    trap_period 5
    timeout 2

In this config file I want to highlight few sections:

  • Cluster hosts addresses and access params - this section describe IPs and credentials that will be used in all monitoring checks. So, it is required to have active MySQL instances listening on these IPs and appropriate access restrictions set to allow monitoring server to MySQL instance.
  • Define roles - this section defines what roles we have in our cluster and what IPs will be used for each role.

All other config sections are pretty standard and described in details in configuration files section of mmm guide.