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Custom Plugin Monitor

Configuration

Plugin Config

  • invoke_interval: Interval at which custom plugins will be invoked.
  • timeout: Time after which custom plugins invocation will be terminated and considered timeout.
  • max_output_length: The maximum standard output size from custom plugins that NPD will be cut and use for condition status message.
  • concurrency: The plugin worker number, i.e., how many custom plugins will be invoked concurrently.
  • enable_message_change_based_condition_update: Flag controls whether message change should result in a condition update.
  • skip_initial_status: Flag controls whether condition will be emitted during plugin initialization.

Rule Config

  • timeout: The execution timeout for one rule. A rule timeout greater than the global timeout fails validation at startup.
  • invoke_interval: The invoke interval for one rule. The rule uses the global invoke_interval when this field is absent. Rules with different effective intervals run on independent schedules. Their plugins can run at the same time, up to the global concurrency limit. A rule never runs concurrently with itself. The monitor runs at most one catch-up batch when a batch overruns its interval.

For example, this rule runs every seven seconds:

{
  "path": "./config/plugin/check_ntp.sh",
  "invoke_interval": "7s"
}

Annotated Plugin Configuration Example

{
  "plugin": "custom",
  "pluginConfig": {
    "invoke_interval": "30s",
    "timeout": "5s",
    "max_output_length": 80,
    "concurrency": 3,
    "enable_message_change_based_condition_update": false
  },
  "source": "ntp-custom-plugin-monitor",
  "metricsReporting": true,
  "conditions": [
    {
      "type": "NTPProblem",
      "reason": "NTPIsUp",              // This is the default reason shown when healthy
      "message": "ntp service is up"    // This is the default message shown when healthy
    }
  ],
  "rules": [
    {
      "type": "temporary",              // These are not shown unless there's an
                                        // event so they always relate to a problem.
                                        // There are no defaults since there is nothing
                                        // to show unless there's a problem.
      "reason": "NTPIsDown",            // This is the reason shown for this event
                                        // and the message shown comes from stdout.
      "path": "./config/plugin/check_ntp.sh",
      "invoke_interval": "7s",
      "timeout": "3s"
    },
    {
      "type": "permanent",              // These are permanent and are shown in the Conditions section
                                        // when running `kubectl describe node ...`
                                        // They have default values shown above in the conditions section
                                        // and also a reason for each specific trigger listed in this rules section.
                                        // Message will come from default for healthy times
                                        // and during unhealthy time message comes from stdout of the check.
 
      "condition": "NTPProblem",        // This is the key to connect to the corresponding condition listed above
      "reason": "NTPIsDown",            // and the reason shown for failures detected in this rule
                                        // and message will be from stdout of the check.
      "path": "./config/plugin/check_ntp.sh",
      "timeout": "3s"
    }
  ]
}