Moleculer

Moleculer is a fast, modern and powerful microservices framework for originally written for Node.js. It helps you to build efficient, reliable & scalable services. Moleculer provides many features for building and managing your microservices.

Getting Started

Install the Gem

gem install "moleculer-ruby"

or add to your Gemfile:

gem "moleculer-ruby", "~>0.3"

Create a Simple Service

class SimpleService < Moleculer::Service::Base
  action :get_user, :get_user
  
  
  def get_user
    # .. usery getting stuff
  end
end


Moleculer.config do |c|
  c.services << SimpleService
end

Moleculer.start

Configuration

Moleculer is configured through the Moleculer::config method. Example:

Moleculer.configure do |c|
  c.log_level = :debug
end

Some Moleculer configuration values can also be set through environment variables.

Configuration Options

rescue_from

Sets an error handler that ties into the infrastructure of Moleculer instructing it how to handle errors of the specified class. This allows things like Airbrake to easily tie in to exception handling. By default Moleculer rescues from StandardError and simply logs it out.

log_file (default: STDOUT)

Sets the moleculer log_file. This value can also be set by setting the MOLECULER_LOG_FILE environment variable.

logger

Sets the moleculer logger. The logger must be an instance of Moleculer::Support::LogProxy. The log proxy supports any ruby logger that supports the ruby Logger interface.

Example:

c.logger = Moleculer::Support::Logger.new(Rails.logger)

In the case that the logger is set to something other than the default, the log level set for moleculer is ignored, and the level of the passed logger is used.

log_level (default: debug)

Sets the log level of the node. defaults to :debug. Can be one of :trace, :debug, :info, :warn, :error, :fatal. This value can also be set by setting the MOLECULER_LOG_LEVEL environment variable.

heartbeat_interval (default: 5)

The interval in which to send heartbeats. This value can also be set by setting the MOLECULER_HEARTBEAT environment variable.

node_id (default: <hostname>-<pid>)

The node id. Node IDs are required to be unique. In Moleculer-ruby all node ids are suffixed with the PID of the running process, allowing multiple copies of the same node to be run on the same machine. When using a containerized environment (i.e. Docker), it is suggested that the node_id also include a random set of characters as there is a chance that does running in separate containers can have the same PID.

serializer (default: :json)

Which serializer to use. For more information serializers see Serialization

service_prefix (default: nil)

The service prefix. This will be prefixed to all services. For example if service_prefix were to be foo then a service whose service_name is set to users would get the full service_name of foo.users.

timeout (default: 5)

The Moleculer system timeout. This is used to determine how long a moleculer call will wait for a response until it times out and throws an error. This value can also be set by setting the MOLECULER_TIMEOUT environment variable.

transporter (default: redis://localhost)

The transporter Moleculer should use. For more information on transporters see Transporters This value can also be set by setting the MOLECULER_TRANSPORTER environment variable.

Roadmap

0.1 (COMPLETE)

Initial release

• Redis transporter
• Round robin load balancing
• Service registry & dynamic service discovery
• JSON serializer

0.2 (COMPLETE)

• Fake transporter (for testing)
• Error handling, (ability to use Airbrake, etc.)

0.3 (COMPLETE)

• Service versioning
• Environment variable based configuration

0.4 (IN PROGRESS)

• Protobuf serializer
• Add MessagePack serializer
• Circuit Breaker support
• Retry support

0.5 (PLANNED)

• Bulkhead support
• Fallback support
• Nested call support