LibvirtAsync

Libvirt event loop asynchronous implementation on Fibers. Based on libvirt-ruby and async. Allows to receive domain events. Allows to work with streams in asynchronous mode.

Installation

Add this line to your application's Gemfile:

gem 'libvirt_async'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install libvirt_async

Usage

LibvirtAsync.register_implementations! must be called once per process before connecting to hypervisor.

Receiving domain events

We can subscribe for event from all hypervisor's domains

require 'libvirt_async'

LibvirtAsync.register_implementations!

connection = Libvirt::open('qemu+tcp://127.0.0.1:16509')

some_object = Object.new

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_LIFECYCLE,
    ->(connection, domain, event, detail, opaque) { 
      puts "LIFECYCLE event #{domain.uuid} #{event} #{detail}" 
    },
    nil, # optional domain, can be omitted
    some_object # will be an opaque in callback, can be omitted
)

Or we can subscribe on particular domain

require 'libvirt_async'

LibvirtAsync.register_implementations!

connection = Libvirt::open('qemu+tcp://127.0.0.1:16509')
domain = connection.list_all_domains.first

some_object = Object.new

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_LIFECYCLE,
    ->(connection, domain, event, detail, opaque) { 
      puts "LIFECYCLE event #{domain.uuid} #{event} #{detail}" 
    },
    domain, 
    some_object # will be an opaque in callback, can be omitted
)

All available domain events:

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_REBOOT,
    ->(connection, domain, opaque) { 
      puts "REBOOT event #{domain.uuid}" 
    }
)

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_RTC_CHANGE,
    ->(connection, domain, utc_offset, opaque) { 
      puts "RTC_CHANGE event #{domain.uuid} #{utc_offset}" 
    }
)

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_WATCHDOG,
    ->(connection, domain, action, opaque) { 
      puts "WATCHDOG event #{domain.uuid} #{action}" 
    }
)

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_IO_ERROR,
    ->(connection, domain, src_path, dev_alias, action, opaque) { 
      puts "IO_ERROR event #{domain.uuid} #{src_path} #{dev_alias} #{action}" 
    }
)

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_IO_ERROR_REASON,
    ->(connection, domain, src_path, dev_alias, action, opaque) { 
      puts "IO_ERROR_REASON event #{domain.uuid} #{src_path} #{dev_alias} #{action}" 
    }
)

connection.domain_event_register_any(
    Libvirt::Connect::DOMAIN_EVENT_ID_GRAPHICS,
    ->(connection, domain, phase, local, remote, auth_scheme, subject, opaque) { 
      puts "GRAPHICS event #{domain.uuid} #{phase} #{local} #{remote} #{auth_scheme} #{subject}" 
    }
)

Taking screenshot

require 'libvirt_async'

LibvirtAsync.register_implementations!

connection = Libvirt::open('qemu+tcp://127.0.0.1:16509')
domain = connection.list_all_domains.first

file = File.new("/screenshots/#{domain.uuid}.pnm", 'wb')
stream = LibvirtAsync::StreamRead.new(connection, file)
mime_type = domain.screenshot(stream.stream, 0)
puts "screenshot saving initiated mime_type=#{mime_type}"

# will start screenshot saving
stream.call do |success, reason, io|
  # this block will be called asynchronously on complete or error
  io.close
  if success
   puts "screenshot saved at #{io.path}"
  else
   puts "screenshot was not saved: #{reason}"
  end
end

Logging.

require 'libvirt_async'

LibvirtAsync.use_logger!
LibvirtAsync.logger.level = Logger::Severity::DEBUG # for debugging
LibvirtAsync.start_debug_logging!(2) # will print implementations debug info to logger each 2 seconds.

Look at ruby-libvirt Documenation for further details.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/senid231/libvirt_async. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

Releasing

$ bundle exec rake release
$ gem push pkg/libvirt_async-X.Y.Z.gem

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the LibvirtAsync project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

libvirt_async

Runtime