Amazon Elastic Load Balancing Add a Host-Based Routing Rule

arazzo: 1.0.1
info:
  title: Amazon Elastic Load Balancing Add a Host-Based Routing Rule
  summary: Create a target group and attach a host-header rule to an existing listener.
  description: >-
    Adds host-based routing to an existing Application Load Balancer listener.
    It creates a new HTTP target group for the backend that should serve a
    specific hostname, then creates a listener rule that forwards requests whose
    host header matches the supplied value to that target group, and finally
    reads the listener's rules back to confirm the new rule landed. Each step
    spells out its request inline so the flow can be read and executed without
    opening the underlying OpenAPI description. The Elastic Load Balancing v2
    API uses the AWS query protocol, so every operation is a GET whose inputs
    are carried as query parameters rather than a request body.
  version: 1.0.0
sourceDescriptions:
- name: rulesApi
  url: ../openapi/amazon-elastic-load-balancing-rules-api-openapi.yml
  type: openapi
- name: targetGroupsApi
  url: ../openapi/amazon-elastic-load-balancing-target-groups-api-openapi.yml
  type: openapi
workflows:
- workflowId: add-host-based-routing-rule
  summary: Create a target group and a host-header forwarding rule on a listener.
  description: >-
    Chains createTargetGroup, createRule, and describeRules so a hostname is
    routed to a dedicated backend and the resulting rule set is confirmed.
  inputs:
    type: object
    required:
    - listenerArn
    - targetGroupName
    - vpcId
    - hostHeader
    - priority
    properties:
      listenerArn:
        type: string
        description: The ARN of the existing listener to attach the rule to.
      targetGroupName:
        type: string
        description: The unique name for the new target group.
      vpcId:
        type: string
        description: The ID of the VPC for the target group.
      port:
        type: integer
        description: The port the targets receive traffic on.
        default: 80
      hostHeader:
        type: string
        description: The host header value to match (e.g. api.example.com).
      priority:
        type: integer
        description: The unique rule priority within the listener (1-50000).
  steps:
  - stepId: createTargetGroup
    description: Create the HTTP target group that the host-based rule will forward to.
    operationId: createTargetGroup
    parameters:
    - name: Name
      in: query
      value: $inputs.targetGroupName
    - name: Protocol
      in: query
      value: HTTP
    - name: Port
      in: query
      value: $inputs.port
    - name: VpcId
      in: query
      value: $inputs.vpcId
    - name: HealthCheckProtocol
      in: query
      value: HTTP
    - name: HealthCheckPath
      in: query
      value: /
    - name: TargetType
      in: query
      value: instance
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      targetGroupArn: $response.body#/targetGroups/0/targetGroupArn
  - stepId: createRule
    description: >-
      Create a host-header condition rule that forwards matching requests to the
      new target group at the supplied priority.
    operationId: createRule
    parameters:
    - name: ListenerArn
      in: query
      value: $inputs.listenerArn
    - name: Priority
      in: query
      value: $inputs.priority
    - name: Conditions.member.1.Field
      in: query
      value: host-header
    - name: Conditions.member.1.Values
      in: query
      value: $inputs.hostHeader
    - name: Actions.member.1.Type
      in: query
      value: forward
    - name: Actions.member.1.TargetGroupArn
      in: query
      value: $steps.createTargetGroup.outputs.targetGroupArn
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      ruleArn: $response.body#/rules/0/ruleArn
  - stepId: describeRules
    description: Read the listener's rules back to confirm the new rule is present.
    operationId: describeRules
    parameters:
    - name: ListenerArn
      in: query
      value: $inputs.listenerArn
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      rules: $response.body#/rules
  outputs:
    targetGroupArn: $steps.createTargetGroup.outputs.targetGroupArn
    ruleArn: $steps.createRule.outputs.ruleArn
    rules: $steps.describeRules.outputs.rules