103 lines
3.4 KiB
Markdown
103 lines
3.4 KiB
Markdown
# NDB Cluster Monitor
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## Overview
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The MySQL Cluster Monitor is a monitoring module for MaxScale that monitors a MySQL Cluster. It assigns a NDB status for the server if it is a part of a MySQL Cluster.
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## Configuration
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A minimal configuration for a monitor requires a set of servers for monitoring and a username and a password to connect to these servers. The user requires the REPLICATION CLIENT privilege to successfully monitor the state of the servers.
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```
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[MySQL Cluster Monitor]
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type=monitor
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module=ndbclustermon
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servers=server1,server2,server3
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user=myuser
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passwd=mypwd
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```
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## Optional parameters for all monitors
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Here are optional parameters that are common for all the monitors.
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### `monitor_interval`
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This is the time the monitor waits between each cycle of monitoring. The default value of 10000 milliseconds (10 seconds) should be lowered if you want a faster response to changes in the server states. The value is defined in milliseconds and the smallest possible value is 100 milliseconds.
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```
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monitor_interval=2500
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```
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### `backend_connect_timeout`
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This parameter controls the timeout for connecting to a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 3 seconds.
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```
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backend_connect_timeout=6
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```
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### `backend_write_timeout`
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This parameter controls the timeout for writing to a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 2 seconds.
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```
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backend_write_timeout=4
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```
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### `backend_read_timeout`
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This parameter controls the timeout for reading from a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 1 seconds.
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```
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backend_read_timeout=2
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```
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## MySQL Cluster Monitor optional parameters
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These are optional parameters specific to the MySQL Cluster Monitor.
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### `script`
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This script will be executed when a server changes its state. The parameter should be an absolute path to the script or it should be in the executable path. The user which is used to run MaxScale should have execution rights to the file itself and the directory it resides in.
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```
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script=/home/user/script.sh
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```
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This script will be called with the following command line arguments.
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```
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<name of the script> --event=<event type> --initiator=<server whose state changed> --nodelist=<list of all servers>
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```
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### `events`
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A list of event names which cause the script to be executed. If this option is not defined, all events cause the script to be executed. The list must contain a comma separated list of event names.
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```
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events=master_down,slave_down
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```
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## Script events
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Here is a table of all possible event types and their descriptions that the MySQL Cluster monitor can be called with.
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Event Name|Description
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----------|----------
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master_down|A Master server has gone down
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master_up|A Master server has come up
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slave_down|A Slave server has gone down
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slave_up|A Slave server has come up
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server_down|A server with no assigned role has gone down
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server_up|A server with no assigned role has come up
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ndb_down|A MySQL Cluster node has gone down
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ndb_up|A MySQL Cluster node has come up
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lost_master|A server lost Master status
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lost_slave|A server lost Slave status
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lost_ndb|A MySQL Cluster node lost node membership
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new_master|A new Master was detected
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new_slave|A new Slave was detected
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new_ndb|A new MySQL Cluster node was found
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