Kubernetes Scale a Deployment and Verify Replicas

arazzo: 1.0.1
info:
  title: Kubernetes Scale a Deployment and Verify Replicas
  summary: Read the current scale of a deployment, set a new replica count, and confirm the pods landed.
  description: >-
    Scaling through the scale subresource rather than replacing the whole
    deployment avoids clobbering concurrent template changes. The workflow
    confirms the deployment exists, reads the current scale, writes the new
    desired replica count, and then lists the deployment's pods to observe the
    result. Every step spells out its request inline so the flow can be read and
    executed without opening the underlying OpenAPI description.
  version: 1.0.0
sourceDescriptions:
- name: workloadsApi
  url: ../openapi/kubernetes-workloads-api-openapi.yml
  type: openapi
workflows:
- workflowId: scale-deployment
  summary: Change a deployment's replica count via the scale subresource and verify.
  description: >-
    Resolves the deployment, reads its current scale for a before value,
    replaces the scale with the desired replica count, and lists the pods
    matching the deployment's label to confirm the change took effect.
  inputs:
    type: object
    required:
    - namespace
    - deploymentName
    - replicas
    properties:
      namespace:
        type: string
        description: The namespace containing the deployment.
      deploymentName:
        type: string
        description: The name of the deployment to scale.
      replicas:
        type: integer
        description: The desired number of replicas to scale to.
      labelSelector:
        type: string
        description: Label selector matching the deployment's pods (e.g. app=nginx).
  steps:
  - stepId: resolveDeployment
    description: >-
      Confirm the deployment exists and capture its current status before
      changing the replica count.
    operationId: getNamespacedDeployment
    parameters:
    - name: namespace
      in: path
      value: $inputs.namespace
    - name: name
      in: path
      value: $inputs.deploymentName
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      deploymentName: $response.body#/metadata/name
      resourceVersion: $response.body#/metadata/resourceVersion
      currentReplicas: $response.body#/status/replicas
  - stepId: readScale
    description: >-
      Read the scale subresource to record the replica count the cluster
      currently considers desired, before this workflow changes it.
    operationId: getNamespacedDeploymentScale
    parameters:
    - name: namespace
      in: path
      value: $inputs.namespace
    - name: name
      in: path
      value: $steps.resolveDeployment.outputs.deploymentName
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      previousDesiredReplicas: $response.body#/spec/replicas
      previousActualReplicas: $response.body#/status/replicas
      scaleResourceVersion: $response.body#/metadata/resourceVersion
  - stepId: applyScale
    description: >-
      Replace the scale subresource with the new desired replica count. The
      deployment controller adds or removes pods to converge on the new value.
    operationId: replaceNamespacedDeploymentScale
    parameters:
    - name: namespace
      in: path
      value: $inputs.namespace
    - name: name
      in: path
      value: $steps.resolveDeployment.outputs.deploymentName
    requestBody:
      contentType: application/json
      payload:
        apiVersion: autoscaling/v1
        kind: Scale
        metadata:
          name: $inputs.deploymentName
          namespace: $inputs.namespace
          resourceVersion: $steps.readScale.outputs.scaleResourceVersion
        spec:
          replicas: $inputs.replicas
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      desiredReplicas: $response.body#/spec/replicas
      actualReplicas: $response.body#/status/replicas
  - stepId: verifyPods
    description: >-
      List the pods carrying the deployment's label to observe the scaling
      result. Pods may still be Pending immediately after scaling up.
    operationId: listNamespacedPods
    parameters:
    - name: namespace
      in: path
      value: $inputs.namespace
    - name: labelSelector
      in: query
      value: $inputs.labelSelector
    - name: limit
      in: query
      value: 500
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      pods: $response.body#/items
      firstPodPhase: $response.body#/items/0/status/phase
  outputs:
    previousDesiredReplicas: $steps.readScale.outputs.previousDesiredReplicas
    desiredReplicas: $steps.applyScale.outputs.desiredReplicas
    pods: $steps.verifyPods.outputs.pods