Check mysql-connections

Overview

Checks the connection usage rate, the rate of aborted connections and if name resolution is active for new connections on MySQL/MariaDB. Logic is taken from MySQLTuner script:mysql_stats(), v1.9.8.

Hints:

Fact Sheet

Check Plugin Download

https://github.com/Linuxfabrik/monitoring-plugins/tree/main/check-plugins/mysql-connections

Check Interval Recommendation

Once a minute

Can be called without parameters

Yes

Available for

Python 3, Windows

Requirements

Python module pymysql; User with no privileges, locked down to 127.0.0.1 - for example monitoring@127.0.0.1. Usernames in MySQL/MariaDB are limited to 16 chars in specific versions.

Help

usage: mysql-connections [-h] [-V] [--always-ok]
                         [--defaults-file DEFAULTS_FILE]
                         [--defaults-group DEFAULTS_GROUP]
                         [--ignore-name-resolution] [--timeout TIMEOUT]

Checks the connection usage rate, the rate of aborted connections and if name
resolution is active for new connections on MySQL/MariaDB.

options:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  --always-ok           Always returns OK.
  --defaults-file DEFAULTS_FILE
                        Specifies a cnf file to read parameters like user,
                        host and password from (instead of specifying them on
                        the command line), for example
                        `/var/spool/icinga2/.my.cnf`. Default:
                        /var/spool/icinga2/.my.cnf
  --defaults-group DEFAULTS_GROUP
                        Group/section to read from in the cnf file. Default:
                        client
  --ignore-name-resolution
                        Do not check if name resolution is active. Default:
                        False
  --timeout TIMEOUT     Network timeout in seconds. Default: 3 (seconds)

Usage Examples

./mysql-connections --defaults-file=/var/spool/icinga2/.my.cnf

Output:

36.4% used (4/11); 0.0% aborted connections (0.0/1.3K); Name resolution is active: A reverse name resolution is made for each new connection and can reduce performance [WARNING]. Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=ON.

States

  • WARN if the number of connections is more than 85% of the maximum possible number of simultaneous client connections (setting max_connections).

  • WARN if the number of aborted connections is more than 3% of all client connections.

  • WARN if name resolution is active (if –ignore-name-resolution is ommitted).

Perfdata / Metrics

Name

Type

Description

mysql_aborted_connects

Continous Counter

Number of failed server connection attempts. This can be due to a client using an incorrect password, a client not having privileges to connect to a database, a connection packet not containing the correct information, or if it takes more than connect_timeout seconds to get a connect packet.

mysql_connections

Continous Counter

Number of all connection attempts (both successful and unsuccessful).

mysql_interactive_timeout

Seconds

Time in seconds that the server waits for an interactive connection (one that connects with the mysql_real_connect() CLIENT_INTERACTIVE option) to become active before closing it.

mysql_max_connections

Number

The maximum number of simultaneous client connections.

mysql_max_used_connections

Number

Max number of connections ever open at the same time.

mysql_pct_connections_aborted

Percentage

Aborted_connects / Connections * 100

mysql_pct_connections_used

Percentage

Max_used_connections / max_connections * 100

mysql_wait_timeout

Seconds

Time in seconds that the server waits for a connection to become active before closing it.

Credits, License