Plugin Helper: Metrics

The metrics plugin helper manages the metrics values in plugins.

Here is an example:

require 'fluent/plugin/input'

module Fluent::Plugin
  class ExampleInput < Input
    Fluent::Plugin.register_input('example', self)

    # 1. Load metrics helper
    helpers :metrics

    def configure(conf)
      super

      # 2. Create parser plugin instance
      @metrics = metrics_create(namespace: "fluentd", subsystem: "input", name: "example", help_text: "Example metrics")
    end

    def start
      super

      # 3. Increase metrics value
      @metrics.inc

    end

    def statistics
      stats = super

      # 4. Retrieve metrics value
      stats = {
        'input' => stats["input"].merge({ 'example' => @metrics.get })
      }
      stats
    end
end

For more details, see the following articles:

• Metrics Plugins Overview

Methods

metrics_create(namespace: "fluentd", subsystem: "metrics", name:, help_text:, labels: {}, prefer_gauge: false)

This method creates a metrics instance.

• namespace: The namespace for the metrics.

• subsystem: The names that represent specific functions or components.

• name: The metrics name.

• help_text: The description for metrics.

• labels: The key/value pair for metrics labels.

• prefer_gauge: Use gauge instead of counter for the metrics if true.

Since 1.19.0, metrics_create method generates a getter method with the specified name on the calling instance.

Plugins using metrics

• buffer

• filter

• input

• output

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.