Amazon EC2 Launch and Await Running

arazzo: 1.0.1
info:
  title: Amazon EC2 Launch and Await Running
  summary: Launch an instance, then poll DescribeInstances until it reaches the running state.
  description: >-
    Launches a single EC2 instance and then polls its state until it transitions
    out of pending into running. The poll step branches on the reported instance
    state name: while pending it loops back to describe again, and once running
    it ends the workflow. Every step spells out its request inline using the
    Amazon EC2 query protocol (Action and Version parameters) so the flow can be
    read and executed without opening the underlying OpenAPI description.
  version: 1.0.0
sourceDescriptions:
- name: amazonEc2Api
  url: ../openapi/amazon-ec2-openapi.yml
  type: openapi
workflows:
- workflowId: launch-and-await-running
  summary: Launch one instance and wait for it to become running before returning.
  description: >-
    Chains RunInstances with a DescribeInstances poll loop that branches on the
    instance state name, looping while pending and ending once running.
  inputs:
    type: object
    required:
    - imageId
    - instanceType
    properties:
      imageId:
        type: string
        description: The AMI ID to launch the instance from.
      instanceType:
        type: string
        description: The EC2 instance type (e.g. t3.micro).
      keyName:
        type: string
        description: Optional name of the key pair to use for SSH access.
  steps:
  - stepId: runInstance
    description: Launch a single instance from the supplied AMI.
    operationId: runInstances
    parameters:
    - name: Action
      in: query
      value: RunInstances
    - name: Version
      in: query
      value: '2016-11-15'
    - name: ImageId
      in: query
      value: $inputs.imageId
    - name: InstanceType
      in: query
      value: $inputs.instanceType
    - name: MinCount
      in: query
      value: 1
    - name: MaxCount
      in: query
      value: 1
    - name: KeyName
      in: query
      value: $inputs.keyName
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      instanceId: $response.body#/instances/0/instanceId
  - stepId: pollState
    description: >-
      Describe the launched instance and branch on its state, looping while
      pending and ending once it reports running.
    operationId: describeInstances
    parameters:
    - name: Action
      in: query
      value: DescribeInstances
    - name: Version
      in: query
      value: '2016-11-15'
    - name: InstanceId
      in: query
      value: $steps.runInstance.outputs.instanceId
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      state: $response.body#/reservationSet/0/instancesSet/0/instanceState/name
      instanceId: $response.body#/reservationSet/0/instancesSet/0/instanceId
    onSuccess:
    - name: stillPending
      type: goto
      stepId: pollState
      criteria:
      - context: $response.body
        condition: $.reservationSet[0].instancesSet[0].instanceState.name == 'pending'
        type: jsonpath
    - name: nowRunning
      type: end
      criteria:
      - context: $response.body
        condition: $.reservationSet[0].instancesSet[0].instanceState.name == 'running'
        type: jsonpath
  outputs:
    instanceId: $steps.pollState.outputs.instanceId
    finalState: $steps.pollState.outputs.state