This package provides an interface to the Amazon Kinesis Client Library's (KCL) MultiLangDaemon for the Ruby language. Developers can use the Amazon KCL to build distributed applications that process streaming data reliably at scale. The Amazon KCL takes care of many of the complex tasks associated with distributed computing, such as load-balancing across multiple instances, responding to instance failures, checkpointing processed records, and reacting to changes in stream volume. This package wraps and manages the interaction with the MultiLangDaemon which is part of the Amazon KCL for Java so that developers can focus on implementing their record processor executable. A record processor in Ruby typically looks something like:
#! /usr/bin/env ruby
require 'aws/kclrb'
class SampleRecordProcessor < Aws::KCLrb::V2::RecordProcessorBase
def init_processor(initialize_input)
# initialize
end
def process_records(process_records_input)
# process batch of records
end
def lease_lost(lease_lost_input)
# lease was lost, cleanup
end
def shard_ended(shard_ended_input)
# shard has ended, cleanup
end
def shutdown_requested(shutdown_requested_input)
# shutdown has been requested
end
end
if __FILE__ == $0
# Start the main processing loop
record_processor = SampleRecordProcessor.new
driver = Aws::KCLrb::KCLProcess.new(record_processor)
driver.run
endBefore running the samples, you'll want to make sure that your environment is configured to allow the samples to use your AWS Security Credentials.
By default the samples use the DefaultAWSCredentialsProviderChain
so you'll want to make your credentials available to one of the credentials providers in that
provider chain. There are several ways to do this such as providing a ~/.aws/credentials file,
or if you're running on Amazon EC2, you can associate an IAM role with your instance with appropriate
access.
For questions regarding Amazon Kinesis Service and the client libraries please check the official documentation as well as the Amazon Kinesis Forums.
Using the Amazon KCL for Ruby package requires the MultiLangDaemon which is provided by the Amazon KCL for Java. Rake tasks are provided to start the sample application(s) and download all the required dependencies.
The sample application consists of two components:
samples/sample_kcl_producer.rb): this script creates an Amazon Kinesis
stream and starts putting random records into it.samples/sample_kcl.rb): this script is invoked by the
MultiLangDaemon and consumes the data from the Amazon Kinesis
stream and stores it into files (1 file per shard).The following defaults are used in the sample application:
kclrbsampleus-east-1RubyKCLSampleRubyKCLSampleRubyKCLSampleTo run the data producer, run the following commands:
cd samples
rake run_producerThe AWS Ruby SDK gem for Kinesis needs to be installed as a pre-requisite. To install, run:
sudo gem install aws-sdk-kinesisThe script samples/sample_kcl_producer.rb takes several parameters that you can use
to customize its behavior. To see the available options, run:
samples/sample_kcl_producer.rb --helpTo run the data processor, run the following commands:
cd samples
rake run properties_file=sample.propertiesJAVA_HOME environment variable needs to point to a valid JVM.The rake task invokes the MultiLangDaemon passing to it the
properties file samples/sample.properties. This file contains the
information needed to bootstrap the sample application, e.g.
executableName = samples/sample_kcl.rbstreamName = kclrbsampleapplicationName = RubyKCLSampleregionName = us-east-1This sample application creates a real Amazon Kinesis stream and sends real data to it, and create a real DynamoDB table to track the Amazon KCL application state, thus potentially incurring AWS costs. Once done, you can log in to AWS management console and delete these resources. Specifically, the sample application will create in your default AWS region
kclrbsampleRubyKCLSampleRunning on Amazon EC2 is simple. Assuming you are already logged into an Amazon EC2
instance running Amazon Linux, the following steps will prepare your environment
for running the sample application. Note the version of Java that ships with
Amazon Linux can be found at /usr/bin/java and should be 1.7 or greater.
# install some prerequisites if missing
sudo yum install gcc patch git ruby rake rubygems ruby-devel
# install the AWS Ruby SDK (pre-requisuite for producer)
sudo gem install aws-sdk aws-kclrb
# clone the git repository to work with the samples
git clone https://github.com/awslabs/amazon-kinesis-client-ruby.git kclrb
# run the sample
cd kclrb/samples
rake run_producer
# ... and in another terminal
rake run properties_file=sample.propertiesAmazon KCL for Ruby uses Amazon KCL for Java internally. We have implemented a Java-based daemon, called the MultiLangDaemon that does all the heavy lifting. Our approach has the daemon spawn the user-defined record processor script/program as a sub-process. The MultiLangDaemon communicates with this sub-process over standard input/output using a simple protocol, and therefore the record processor script/program can be written in any language.
At runtime, there will always be a one-to-one correspondence between a record processor, a child process, and an Amazon Kinesis Shard. The MultiLangDaemon will make sure of that, without any need for the developer to intervene.
In this release, we have abstracted these implementation details away and exposed an interface that enables you to focus on writing record processing logic in Ruby. This approach enables Amazon KCL to be language agnostic, while providing identical features and similar parallel processing model across all languages.
pom.xml in the gemspecRegisterStreamConsumerSubscribeToShardDescribeStreamConsumerDescribeStreamSummaryRecordProcessorBase which supports the new ShardRecordProcessor interface
shutdown method from version 1 has been replaced by lease_lost and shard_ended.lease_lost method which is invoked when a lease is lost.lease_lost replaces shutdown(checkpointer, 'ZOMBIE').shard_ended method which is invoked when all records from a split or merge have been processed.shard_ended replaces shutdown(checkpointer, 'TERMINATE').shutdown_requested, which provides the record processor a last chance to checkpoint during the Amazon Kinesis Client Library shutdown process before the lease is canceled. timeoutInSeconds=<seconds to wait> to your properties file.log_configuration=<log configuration file> to the Rake command line.This library is licensed under the Apache 2.0 License.