8.2. Watchdog Configuration Example

8.2.1.1. Enabling watchdog

First of all, set use_watchdog to on.

      use_watchdog = on
      # Activates watchdog
     

8.2.1.2. Configure Up stream servers

Specify the up stream servers (e.g. application servers). Leaving it blank is also fine.

     trusted_servers = ''
     # trusted server list which are used
     # to confirm network connection
     # (hostA,hostB,hostC,...)
    

8.2.1.3. Watchdog Communication

Specify the TCP port number for watchdog communication.

     wd_port = 9000
     # port number for watchdog service
    

8.2.1.4. Virtual IP

Specify the IP address to be used as a virtual IP address in the delegate_IP.

      delegate_IP = '133.137.177.143'
      # delegate IP address
     

8.2.2.1. Active (osspc16) Server configurations

     other_pgpool_hostname0 = 'osspc20'
     # Host name or IP address to connect to for other pgpool 0
     other_pgpool_port0 = 9999
     # Port number for other pgpool 0
     other_wd_port0 = 9000
     # Port number for other watchdog 0
    

8.2.2.2. Standby (osspc20) Server configurations

     other_pgpool_hostname0 = 'osspc16'
     # Host name or IP address to connect to for other pgpool 0
     other_pgpool_port0 = 9999
     # Port number for other pgpool 0
     other_wd_port0 = 9000
     # Port number for other watchdog 0
    

8.2.3.1. Starting pgpool in Active server (osspc16)

First start the Pgpool-II on Active server.

     [user@osspc16]$ su -
     [root@osspc16]# {installed_dir}/bin/pgpool -n -f {installed_dir}/etc/pgpool.conf > pgpool.log 2>&1
    

Log messages will show that Pgpool-II has the virtual IP address and starts watchdog process.

     LOG:  I am announcing my self as master/coordinator watchdog node
     LOG:  I am the cluster leader node
     DETAIL:  our declare coordinator message is accepted by all nodes
     LOG:  I am the cluster leader node. Starting escalation process
     LOG:  escalation process started with PID:59449
     LOG:  watchdog process is initialized
      LOG:  watchdog: escalation started
      LOG:  I am the master watchdog node
     DETAIL:  using the local backend node status
    

8.2.3.2. Starting pgpool in Standby server (osspc20)

Now start the Pgpool-II on Standby server.

     [user@osspc20]$ su -
     [root@osspc20]# {installed_dir}/bin/pgpool -n -f {installed_dir}/etc/pgpool.conf > pgpool.log 2>&1
    

Log messages will show that Pgpool-II has joined the watchdog cluster as standby watchdog.

     LOG:  watchdog cluster configured with 1 remote nodes
     LOG:  watchdog remote node:0 on Linux_osspc16_9000:9000
     LOG:  interface monitoring is disabled in watchdog
     LOG:  IPC socket path: "/tmp/.s.PGPOOLWD_CMD.9000"
     LOG:  watchdog node state changed from [DEAD] to [LOADING]
     LOG:  new outbound connection to Linux_osspc16_9000:9000
     LOG:  watchdog node state changed from [LOADING] to [INITIALIZING]
     LOG:  watchdog node state changed from [INITIALIZING] to [STANDBY]
           LOG:  successfully joined the watchdog cluster as standby node
      DETAIL:  our join coordinator request is accepted by cluster leader node "Linux_osspc16_9000"
      LOG:  watchdog process is initialized
     
    

8.2.6.1. Lifecheck

There are the parameters about watchdog's monitoring. Specify the interval to check wd_interval and the type of lifecheck wd_lifecheck_method. The hearbeat method specify the time to detect a fault wd_heartbeat_deadtime, the port number to receive wd_heartbeat_port, the interval to send wd_heartbeat_keepalive, the IP address or hostname of destination heartbeat_destination<emphasis>0</emphasis> and finally the destination port number heartbeat_destination_port<emphasis>0</emphasis>.

	    wd_lifecheck_method = 'heartbeat'
	    # Method of watchdog lifecheck ('heartbeat' or 'query' or 'external')
	    # (change requires restart)
	    wd_interval = 10
	    # lifecheck interval (sec) > 0
	    wd_heartbeat_port = 9694
	    # Port number for receiving heartbeat signal
	    # (change requires restart)
	    wd_heartbeat_keepalive = 2
	    # Interval time of sending heartbeat signal (sec)
	    # (change requires restart)
	    wd_heartbeat_deadtime = 30
	    # Deadtime interval for heartbeat signal (sec)
	    # (change requires restart)
	    heartbeat_destination0 = 'host0_ip1'
	    # Host name or IP address of destination 0
	    # for sending heartbeat signal.
	    # (change requires restart)
	    heartbeat_destination_port0 = 9694
	    # Port number of destination 0 for sending
	    # heartbeat signal. Usually this is the
	    # same as wd_heartbeat_port.
	    # (change requires restart)
	   

8.2.6.2. Switching virtual IP address

There are the parameters for switching the virtual IP address. Specify switching commands if_up_cmd, if_down_cmd, the path to them if_cmd_path, the command executed after switching to send ARP request arping_cmd and the path to it arping_path.

	  if_cmd_path = '/sbin'
	  # path to the directory where if_up/down_cmd exists
	  if_up_cmd = 'ip addr add $_IP_$/24 dev eth0 label eth0:0'
	  # startup delegate IP command
	  if_down_cmd = 'ip addr del $_IP_$/24 dev eth0'
	  # shutdown delegate IP command

	  arping_path = '/usr/sbin'           # arping command path

	  arping_cmd = 'arping -U $_IP_$ -w 1'
	 

You can also bring up and bring down the virtual IP using arbitrary scripts specified wd_escalation_command and wd_de_escalation_command parameters.