Class: Koch::SystemdTimerService

Inherits:
Resource
  • Object
show all
Defined in:
lib/koch/systemd_timer_service.rb

Overview

A systemd service that is triggered by a timer

Instance Attribute Summary

Attributes inherited from Resource

#changed, #name

Instance Method Summary collapse

Methods inherited from Resource

dsl_writer

Constructor Details

#initialize(name) ⇒ SystemdTimerService

Returns a new instance of SystemdTimerService.



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# File 'lib/koch/systemd_timer_service.rb', line 11

def initialize(name)
  super
  # Pick a pseudo-random time between 00:00 and 06:00 (360 minutes)
  hash = Zlib.crc32(name) % 360
  hour = hash / 60
  minute = hash % 60
  @timer = format("OnCalendar=%02d:%02d", hour, minute)
end

Instance Method Details

#apply! ⇒ Object

rubocop:disable Metrics/AbcSize rubocop:disable Metrics/MethodLength rubocop:disable Metrics/CyclomaticComplexity rubocop:disable Metrics/PerceivedComplexity



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# File 'lib/koch/systemd_timer_service.rb', line 24

def apply!
  fatal "Systemd services require contents." if contents.nil?

  name_prefix = "/etc/systemd/system/#{name}"
  old_contents = begin
    File.read("#{name_prefix}.service")
  rescue Errno::ENOENT
    nil
  end

  old_timer_contents = begin
    File.read("#{name_prefix}.timer")
  rescue Errno::ENOENT
    nil
  end

  new_timer_contents = <<~TIMER
    [Unit]
    Description=Run #{name} regularly

    [Timer]
    #{@timer}

    [Install]
    WantedBy=timers.target
  TIMER
  if old_contents == contents && old_timer_contents == new_timer_contents
    debug "Systemd #{name} service and timer unchanged"
    return
  end

  @changed = true

  if old_contents != contents
    info "Diff for Systemd service #{name}:"
    info diff(old_contents, contents)
    maybe("Changed Systemd service #{name}") do
      File.write("#{name_prefix}.service", contents)
    end
  end

  if old_timer_contents != new_timer_contents
    info "Diff for Systemd timer #{name}:"
    info diff(old_timer_contents, new_timer_contents)

    maybe("Changed Systemd timer #{name}") do
      File.write("#{name_prefix}.timer", new_timer_contents)
    end
  end

  if system("systemctl is-enabled --quiet #{name}.timer")
    maybe "systemctl daemon-reload"
  else
    maybe "systemctl enable --now #{name}.timer"
  end
end