Fluentd
1.0
1.0
  • Introduction
  • Overview
    • Life of a Fluentd event
    • Support
    • FAQ
    • Logo
    • fluent-package v5 vs td-agent v4
  • Installation
    • Before Installation
    • Install fluent-package
      • RPM Package (Red Hat Linux)
      • DEB Package (Debian/Ubuntu)
      • .dmg Package (macOS)
      • .msi Installer (Windows)
    • Install calyptia-fluentd
      • RPM Package (Red Hat Linux)
      • DEB Package (Debian/Ubuntu)
      • .dmg Package (macOS)
      • .msi Installer (Windows)
    • Install by Ruby Gem
    • Install from Source
    • Post Installation Guide
    • Obsolete Installation
      • Treasure Agent v4 (EOL) Installation
        • Install by RPM Package v4 (Red Hat Linux)
        • Install by DEB Package v4 (Debian/Ubuntu)
        • Install by .dmg Package v4 (macOS)
        • Install by .msi Installer v4 (Windows)
      • Treasure Agent v3 (EOL) Installation
        • Install by RPM Package v3 (Red Hat Linux)
        • Install by DEB Package v3 (Debian/Ubuntu)
        • Install by .dmg Package v3 (macOS)
        • Install by .msi Installer v3 (Windows)
  • Configuration
    • Config File Syntax
    • Config File Syntax (YAML)
    • Routing Examples
    • Config: Common Parameters
    • Config: Parse Section
    • Config: Buffer Section
    • Config: Format Section
    • Config: Extract Section
    • Config: Inject Section
    • Config: Transport Section
    • Config: Storage Section
    • Config: Service Discovery Section
  • Deployment
    • System Configuration
    • Logging
    • Signals
    • RPC
    • High Availability Config
    • Performance Tuning
    • Multi Process Workers
    • Failure Scenarios
    • Plugin Management
    • Trouble Shooting
    • Fluentd UI
    • Linux Capability
    • Command Line Option
    • Source Only Mode
    • Zero-downtime restart
  • Container Deployment
    • Docker Image
    • Docker Logging Driver
    • Docker Compose
    • Kubernetes
  • Monitoring Fluentd
    • Overview
    • Monitoring by Prometheus
    • Monitoring by REST API
  • Input Plugins
    • tail
    • forward
    • udp
    • tcp
    • unix
    • http
    • syslog
    • exec
    • sample
    • monitor_agent
    • windows_eventlog
  • Output Plugins
    • file
    • forward
    • http
    • exec
    • exec_filter
    • secondary_file
    • copy
    • relabel
    • roundrobin
    • stdout
    • null
    • s3
    • kafka
    • elasticsearch
    • opensearch
    • mongo
    • mongo_replset
    • rewrite_tag_filter
    • webhdfs
    • buffer
  • Filter Plugins
    • record_transformer
    • grep
    • parser
    • geoip
    • stdout
  • Parser Plugins
    • regexp
    • apache2
    • apache_error
    • nginx
    • syslog
    • ltsv
    • csv
    • tsv
    • json
    • msgpack
    • multiline
    • none
  • Formatter Plugins
    • out_file
    • json
    • ltsv
    • csv
    • msgpack
    • hash
    • single_value
    • stdout
    • tsv
  • Buffer Plugins
    • memory
    • file
    • file_single
  • Storage Plugins
    • local
  • Service Discovery Plugins
    • static
    • file
    • srv
  • Metrics Plugins
    • local
  • How-to Guides
    • Stream Analytics with Materialize
    • Send Apache Logs to S3
    • Send Apache Logs to Minio
    • Send Apache Logs to Mongodb
    • Send Syslog Data to Graylog
    • Send Syslog Data to InfluxDB
    • Send Syslog Data to Sematext
    • Data Analytics with Treasure Data
    • Data Collection with Hadoop (HDFS)
    • Simple Stream Processing with Fluentd
    • Stream Processing with Norikra
    • Stream Processing with Kinesis
    • Free Alternative To Splunk
    • Email Alerting like Splunk
    • How to Parse Syslog Messages
    • Cloud Data Logging with Raspberry Pi
  • Language Bindings
    • Java
    • Ruby
    • Python
    • Perl
    • PHP
    • Nodejs
    • Scala
  • Plugin Development
    • How to Write Input Plugin
    • How to Write Base Plugin
    • How to Write Buffer Plugin
    • How to Write Filter Plugin
    • How to Write Formatter Plugin
    • How to Write Output Plugin
    • How to Write Parser Plugin
    • How to Write Storage Plugin
    • How to Write Service Discovery Plugin
    • How to Write Tests for Plugin
    • Configuration Parameter Types
    • Upgrade Plugin from v0.12
  • Plugin Helper API
    • Plugin Helper: Child Process
    • Plugin Helper: Compat Parameters
    • Plugin Helper: Event Emitter
    • Plugin Helper: Event Loop
    • Plugin Helper: Extract
    • Plugin Helper: Formatter
    • Plugin Helper: Inject
    • Plugin Helper: Parser
    • Plugin Helper: Record Accessor
    • Plugin Helper: Server
    • Plugin Helper: Socket
    • Plugin Helper: Storage
    • Plugin Helper: Thread
    • Plugin Helper: Timer
    • Plugin Helper: Http Server
    • Plugin Helper: Service Discovery
  • Troubleshooting Guide
  • Appendix
    • Update from v0.12 to v1
    • td-agent v2 vs v3 vs v4
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  • Methods
  • child_process_execute(title, sub_process_name, arguments: nil, subprocess_name: nil, interval: nil, immediate: false, parallel: false, mode: [:read, :write], stderr: :discard, env: {}, unsetenv: false, chdir: nil, internal_encoding: 'utf-8', external_encoding: 'ascii-8bit', scrub: true, replace_string: nil, wait_timeout: nil, on_exit_callback: nil, &block)
  • Plugins using child_process

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  1. Plugin Helper API

Plugin Helper: Child Process

The child_process helper manages the child processes' lifecycle.

Here is an example:

require 'fluent/plugin/output'

module Fluent::Plugin
  class ExampleOutput < Output
    Fluent::Plugin.register_output('example', self)

    # 1. Load child_process helper
    helpers :child_process

    # Omit configure, shutdown and other plugin API

    def start
      super
      # 2. Execute child process with unique name
      child_process_execute(:exec_external_command, 'external_command', immediate: true, mode: [:read]) do
        # ...
      end
    end
  end
end

The launched child process is managed by the plugin helper which automatically shutdowns it.

Methods

child_process_execute(title, sub_process_name, arguments: nil, subprocess_name: nil, interval: nil, immediate: false, parallel: false, mode: [:read, :write], stderr: :discard, env: {}, unsetenv: false, chdir: nil, internal_encoding: 'utf-8', external_encoding: 'ascii-8bit', scrub: true, replace_string: nil, wait_timeout: nil, on_exit_callback: nil, &block)

This method executes child_process with the given parameters and routine.

  • title: unique symbol value

  • sub_process_name: sub process name value

  • interval: Second unit integer/float value.

  • immediate: true/false. Default is false.

  • parallel: true/false. Default is false.

  • mode: [:read, :write]. Default is [:read, :write].

  • stderr: Connect stderr or not. Default is :discard.

  • env: Environment valuables. Default is {}.

  • unsetenv: true/false. Default is false

  • chdir: Working directory. Default is nil.

  • internal_encoding: Internal character encoding. Default is utf-8.

  • external_encoding: External character encoding. Default is ascii-8bit'

  • scrub: true/false. Default is true.

  • replace_string: Replace the invalid code point with the specified character.

    Default is nil.

  • wait_timeout: Set timeout seconds. Default is nil.

  • on_exit_callback: Set callback function. Default is nil

Code examples:

# Pass block directly. block is executed with 10 second interval.
child_process_execute(:exec_awesome_command, @command, interval: 10, mode: [:read]) do |io|
  # ...
end

# Pass block with existing method. block is executed once.
child_process_execute(:exec_awesome_command, @command, immediate: true, mode: [:read], &method(:run))

def run(io)
  # ...
end

Plugins using child_process

PreviousPlugin Helper APINextPlugin Helper: Compat Parameters

Last updated 3 years ago

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If this article is incorrect or outdated, or omits critical information, please . is an open-source project under . All components are available under the Apache 2 License.

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