Class: Fluent::Plugin::PrometheusTailMonitorInput

Inherits:
Input
  • Object
show all
Includes:
PrometheusLabelParser
Defined in:
lib/fluent/plugin/in_prometheus_tail_monitor.rb

Constant Summary collapse

MONITOR_IVARS = 
[
  :tails,
]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from PrometheusLabelParser

#parse_labels_elements

Constructor Details

#initialize ⇒ PrometheusTailMonitorInput

Returns a new instance of PrometheusTailMonitorInput.



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 19

def initialize
  super
  @registry = ::Prometheus::Client.registry
end

Instance Attribute Details

#registry ⇒ Object (readonly)

Returns the value of attribute registry.



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 13

def registry
  @registry
end

Instance Method Details

#configure(conf) ⇒ Object 



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 28

def configure(conf)
  super
  hostname = Socket.gethostname
  expander_builder = Fluent::Plugin::Prometheus.placeholder_expander(log)
  expander = expander_builder.build({ 'hostname' => hostname, 'worker_id' => fluentd_worker_id })
  @base_labels = parse_labels_elements(conf)
  @base_labels.each do |key, value|
    unless value.is_a?(String)
      raise Fluent::ConfigError, "record accessor syntax is not available in prometheus_tail_monitor"
    end
    @base_labels[key] = expander.expand(value)
  end

  @monitor_agent = Fluent::Plugin::MonitorAgentInput.new
end

#get_gauge(name, docstring) ⇒ Object 



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 90

def get_gauge(name, docstring)
  if @registry.exist?(name)
    @registry.get(name)
  else
    @registry.gauge(name, docstring: docstring, labels: @base_labels.keys + [:plugin_id, :type, :path])
  end
end

#labels(plugin_info, path) ⇒ Object 



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 82

def labels(plugin_info, path)
  @base_labels.merge(
    plugin_id: plugin_info["plugin_id"],
    type: plugin_info["type"],
    path: path,
  )
end

#multi_workers_ready? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 24

def multi_workers_ready?
  true
end

#start ⇒ Object 



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 44

def start
  super

  @metrics = {
    position: get_gauge(
      :fluentd_tail_file_position,
      'Current position of file.'),
    inode: get_gauge(
      :fluentd_tail_file_inode,
      'Current inode of file.'),
  }
  timer_execute(:in_prometheus_tail_monitor, @interval, &method(:update_monitor_info))
end

#update_monitor_info ⇒ Object 



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# File 'lib/fluent/plugin/in_prometheus_tail_monitor.rb', line 58

def update_monitor_info
  opts = {
    ivars: MONITOR_IVARS,
  }

  agent_info = @monitor_agent.plugins_info_all(opts).select {|info|
    info['type'] == 'tail'.freeze
  }

  agent_info.each do |info|
    tails = info['instance_variables'][:tails]
    next if tails.nil?

    tails.clone.each do |_, watcher|
      # Access to internal variable of internal class...
      # Very fragile implementation
      pe = watcher.instance_variable_get(:@pe)
      label = labels(info, watcher.path)
      @metrics[:inode].set(pe.read_inode, labels: label)
      @metrics[:position].set(pe.read_pos, labels: label)
    end
  end
end