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.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)
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 valuesub_process_name: sub process name valueinterval: Second unitinteger/floatvalue.immediate:true/false. Default isfalse.parallel:true/false. Default isfalse.mode: [:read,:write]. Default is [:read,:write].stderr: Connect stderr or not. Default is:discard.env: Environment valuables. Default is {}.unsetenv:true/false. Default isfalsechdir: Working directory. Default isnil.internal_encoding: Internal character encoding. Default isutf-8.external_encoding: External character encoding. Default isascii-8bit'scrub:true/false. Default istrue.replace_string: Replace the invalid code point with the specified character.Default isnil.wait_timeout: Set timeout seconds. Default isnil.on_exit_callback: Set callback function. Default isnil
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
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.
Last modified 1yr ago