Simplerubysteps

Simplerubysteps makes it easy to manage AWS Step Functions with ruby (this is an early alpha version and should not really be used by anyone).

Installation and Usage

Prerequisites

• AWS CLI installed (mainly for debugging privileges)
• Configured AWS CLI profile with sufficient permissions to create IAM roles and policies, create Lambda functions, create and run Step Functions state machines, run CloudWatch log queries, etc.

Install the gem and the srs CLI

gem install simplerubysteps

Create an AWS Step Function State Machine with the simplerubysteps Ruby DSL

mkdir -p samples/hello-world
cd samples/hello-world

vi workflow.rb

Hello World State Machine (workflow.rb)

require "simplerubysteps"
include Simplerubysteps

kind "EXPRESS"

task :start do
  transition_to :even do |data|
    data["number"] % 2 == 0
  end

  default_transition_to :odd
end

task :even do
  action do |data|
    number = data["number"]

    puts "Just for the record, I've discovered an even number: #{number}"

    {
      result: "#{number} is even",
    }
  end
end

task :odd do
  action do |data|
    {
      result: "#{data["number"]} is odd",
    }
  end
end

Deploy the Step Functions State Machine and the Lambda function that implements the Task Actions.

export AWS_PROFILE=<AWS CLI profile name with sufficient privileges>
cd samples/hello-world

srs deploy

Trigger State Machine executions

export AWS_PROFILE=<AWS CLI profile name with sufficient privileges>
cd samples/hello-world

echo "Enter a number"
read NUMBER

echo "{\"number\":$NUMBER}" | srs start | jq -r ".output" | jq -r ".result"
# Above: will print "123 is odd" for input "123"

Delete CloudFormation stack

export AWS_PROFILE=<AWS CLI profile name with sufficient privileges>

srs destroy

Development

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

TODOs

• Custom IAM policies per Lambda task (e.g. to allow a task to send a message to an SQS queue)
• Workflow action unit test support
• Better error handling and reporting
• ...

Contributing

Bug reports and pull requests are (soon - after alpha phase) welcome on GitHub at https://github.com/chtz/simplerubysteps

License

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