pmp-check-mysql-status

pmp-check-mysql-status - Check MySQL SHOW GLOBAL STATUS output.

SYNOPSIS

Usage: pmp-check-mysql-status [OPTIONS]
Options:
  -c CRIT         Critical threshold.
  --defaults-file FILE Only read mysql options from the given file.
                  Defaults to /etc/nagios/mysql.cnf if it exists.
  -C COMPARE      Comparison operator to apply to -c and -w.
                  Possible values: == != >= > < <=. Default >=.
  -H HOST         MySQL hostname.
  -I INCR         Make SHOW STATUS incremental over this delay.
  -l USER         MySQL username.
  -L LOGIN-PATH   Use login-path to access MySQL (with MySQL client 5.6).
  -o OPERATOR     The operator to apply to -x and -y.
  -p PASS         MySQL password.
  -P PORT         MySQL port.
  -S SOCKET       MySQL socket file.
  -T TRANS        Transformation to apply before comparing to -c and -w.
                  Possible values: pct str.
  -w WARN         Warning threshold.
  -x VAR1         Required first status or configuration variable.
  -y VAR2         Optional second status or configuration variable.
  --help          Print help and exit.
  --version       Print version and exit.
Options must be given as --option value, not --option=value or -Ovalue.
Use perldoc to read embedded documentation with more details.

DESCRIPTION

This Nagios plugin captures SHOW GLOBAL STATUS and SHOW GLOBAL VARIABLES from MySQL and evaluates expressions against them. The general syntax is as follows:

VAR1 [ OPERATOR VAR2 [ TRANSFORM ] ]

The result of evaluating this is compared against the -w and -c options as usual to determine whether to raise a warning or critical alert.

Note that all of the examples provided below are simply for illustrative purposes and are not supposed to be recommendations for what to monitor. You should get advice from a professional if you are not sure what you should be monitoring.

For our first example, we will raise a warning if Threads_running is 20 or over, and a critical alert if it is 40 or over:

-x Threads_running -w 20 -c 40

The threshold is implemented as greater-or-equals by default, not strictly greater-than, so a value of 20 is a warning and a value of 40 is critical. You can switch this to less-or-equals or other operators with the -C option, which accepts the arithmetic comparison operators ==, !=, >, >=, <, and <=.

You can use any variable that is present in SHOW VARIABLES or SHOW STATUS. If the variable is not found, there is an error. To warn if Threads_connected exceeds 80% of max_connections:

-x Threads_connected -o / -y max_connections -T pct -w 80

The -T pct option only works when you specify both -x and -y and implements percentage transformation. The plugin uses awk to do its computations and comparisons, so you can use floating-point math; you are not restricted to integers for comparisons. Floating-point numbers are printed with six digits of precision. The -o option accepts the arithmetic operators /, *, +, and -. A division by zero results in zero, not an error.

If you specify the -I option with an integer argument, the SHOW STATUS values become incremental instead of absolute. The argument is used as a delay in seconds, and instead of capturing a single sample of SHOW STATUS and using it for computations, the plugin captures two samples at the specified interval and subtracts the second from the first. This lets you evaluate expressions over a range of time. For example, to warn when there are 10 disk-based temporary tables per second, over a 5-second sampling period:

-x Created_tmp_disk_tables -o / -y Uptime -I 5 -w 10

That is somewhat contrived, because it could also be written as follows:

-x Created_tmp_disk_tables -I 5 -w 50

The -I option has the side effect of removing any non-numeric SHOW STATUS variables. Be careful not to set the -I option too large, or Nagios will simply time the plugin out, usually after about 10 seconds.

This plugin does not support arbitrarily complex expressions, such as computing the query cache hit ratio and alerting if it is less than some percentage. If you are trying to do that, you might be doing it wrong. A dubious example for the query cache might be to alert if the hit-to-insert ratio falls below 2:1, as follows:

-x Qcache_hits -o / -y Qcache_inserts -C '<' -w 2

Some people might suggest that the following is a more useful alert for the query cache:

-x query_cache_size -c 1

To check Percona XtraDB Cluster node status you may want to use the following alert similar to what its clustercheck does:

-x wsrep_local_state -C '!=' -w 4

To compare string variables use -T str transformation. This is required as numeric and string comparisons are handled differently. The following example warns when the slave_exec_mode is IDEMPOTENT:

-x slave_exec_mode -C '==' -T str -w IDEMPOTENT

PRIVILEGES

This plugin executes the following commands against MySQL:

  • SHOW STATUS.
  • SHOW VARIABLES.

This plugin executes no UNIX commands that may need special privileges.

VERSION

Percona Monitoring Plugins pmp-check-mysql-status 1.1.4

© Copyright 2012, Percona Inc.
Except where otherwise noted, this documentation is licensed under the following license:
CC Attribution-ShareAlike 2.0 Generic
This documentation is developed in Launchpad as part of the Percona Monitoring Plugins source code.
If you spotted innacuracies, errors, don't understood it or you think something is missing or should be improved, please file a bug.