check-mysql is a check plugin for monitoring MySQL. It can perform check monitoring based on the conditions of the subcommands used.
Subcommand
The available subcommands are as follows.
| Command | Monitoring | Monitoring Target | Note |
|---|---|---|---|
| uptime | MySQL Server uptime | uptime value of SHOW GLOBAL STATUS |
|
| readonly | Whether MySQL server is set to read-only | read_only value of SHOW GLOBAL VARIABLES |
|
| replication | Replication status of MySQL server | - Whether IO_Running and SQL_Running in SHOW REPLICA STATUS are both set to Yes- Whether the value of Seconds_Behind over the threshold |
- REPLICATION CLIENT privilege is required for the connecting user - In version before MySQL 8.0.22, use SHOW SLAVE STATUS. |
| connection | Number of MySQL server connections | Threads_connected value of SHOW GLOBAL STATUS |
Configurable options
The following options can be specified for all subcommands.
| Option | Short | Description | Default |
|---|---|---|---|
| --host | -H | Target host | localhost |
| --port | -p | Connection port | 3306 |
| --socket | -S | Socket file | |
| --user | -u | User name | root |
| --password | -P | Password | |
| --tls | Enable TLS connection | ||
| --tls-root-cert | Specify the root certificate to be used for the TLS connection | ||
| --tls-skip-verify | Do not validate certificates during TLS connections | ||
| --help | -h | Show help ex. check-mysql connection -h |
Threshold Option
The following options for threshold values have different conditions depending on the subcommand. If you don't specify the option, it defaults to the threshold.
| Subcommand | Option | Short | Description | Default |
|---|---|---|---|---|
| uptime | --critical --warning |
-c -w |
If Uptime is less than the specified number of seconds | 0 critical 0 warning |
| readonly | none | |||
| replication | --critical --warning |
-c -w |
If Seconds_Behind exceeds the specified number of seconds | 250 critical 200 warning |
| connection | --critical --warning |
-c -w |
If Threads_Connected exceeds the specified number | 250 critical 200 warning |
Example configurations
The following configuration will generate a Warning alert when the number of MYSQL connections exceeds 250 and a Critical alert when the number exceeds 280.
[plugin.checks.check-mysql-sample] command = ["check-mysql", "connection", "--host", "127.0.0.1", "--port", "3306", "--user", "USER", "--password", "PASSWORD", "--warning", "250", "--critical", "280"]
To check the above settings directly from a terminal, execute as follows.
check-mysql connection --host 127.0.0.1 --port 3306 --user USER --password PASSWORD --warning 250 --critical280
Tips
How to write MySQL connection information
If you want to avoid putting the connection information needed to run check-mysql directly in the --password option, you can take the following approaches. Note that these approaches require that the contents of command be written as a string, not an array.
Use the command
If you specify a string, the contents of command will be executed via the shell, so you can use the command to output the password.
mackerel-agent.conf
command = "check-mysql ... --password "<Command to output password>"
Using Environment Variables
You can define environment variables in the configuration file and optionally specify variables.
mackerel-agent.conf
command = "check-mysql ... --password $MYSQL_PASSWORD ..."
env = { "MYSQL_PASSWORD" = "xxxxx" }
You can also use environment variables applied to mackerel-agent processes. For details, please refer to Applying Environment Variables.
Troubleshooting
"Couldn't..." error message was output
There are following possibility.
- Connection information is incorrect
- The user being connected does not have permission to view MySQL information
Run check-mysql manually on the host and see if you can get any information.
Repository
https://github.com/mackerelio/go-check-plugins/tree/master/check-mysql
