Docker Create a Volume and Mount It Into a Container

arazzo: 1.0.1
info:
  title: Docker Create a Volume and Mount It Into a Container
  summary: Create a named volume, create a container that binds it to a mount path, start the container, and confirm the volume is in use.
  description: >-
    The persistence flow. A named volume is what survives a container being
    recreated, so this is the pattern behind any stateful workload — databases,
    uploads, caches. The workflow creates the volume, creates a container whose
    HostConfig mounts it at a target path, starts it, and inspects the volume to
    confirm the daemon has it mounted rather than dangling. 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: containerApi
  url: ../openapi/docker-container-api-openapi.yml
  type: openapi
- name: volumeApi
  url: ../openapi/docker-volume-api-openapi.yml
  type: openapi
workflows:
- workflowId: provision-volume-and-mount
  summary: Create a named volume and bring up a container with it mounted.
  description: >-
    Creates a named volume with the local driver, creates a container that mounts
    that volume at the supplied target path, starts the container, and reads the
    volume back to confirm it exists and is in use.
  inputs:
    type: object
    required:
    - volumeName
    - image
    - containerName
    - mountPath
    properties:
      volumeName:
        type: string
        description: Name for the volume to create (e.g. "pgdata").
      driver:
        type: string
        description: Volume driver to use. Defaults to "local".
      image:
        type: string
        description: Image to create the container from. It must already be present locally.
      containerName:
        type: string
        description: Name to assign to the created container.
      mountPath:
        type: string
        description: Path inside the container where the volume is mounted (e.g. "/var/lib/postgresql/data").
      env:
        type: array
        description: Environment variables for the container, in "KEY=value" form.
        items:
          type: string
  steps:
  - stepId: createVolume
    description: >-
      Create the named volume. Naming it explicitly is what separates it from an
      anonymous volume that would be swept away with the container.
    operationId: VolumeCreate
    requestBody:
      contentType: application/json
      payload:
        Name: $inputs.volumeName
        Driver: $inputs.driver
        Labels:
          com.apievangelist.workflow: provision-volume-and-mount
    successCriteria:
    - condition: $statusCode == 201
    outputs:
      volumeName: $response.body#/Name
      mountpoint: $response.body#/Mountpoint
      createdAt: $response.body#/CreatedAt
  - stepId: createContainer
    description: >-
      Create a container that mounts the named volume at the target path via a
      HostConfig volume mount, so data written there outlives the container.
    operationId: ContainerCreate
    parameters:
    - name: name
      in: query
      value: $inputs.containerName
    requestBody:
      contentType: application/json
      payload:
        Image: $inputs.image
        Env: $inputs.env
        AttachStdout: true
        AttachStderr: true
        Tty: false
        HostConfig:
          Mounts:
          - Type: volume
            Source: $inputs.volumeName
            Target: $inputs.mountPath
            ReadOnly: false
          RestartPolicy:
            Name: unless-stopped
    successCriteria:
    - condition: $statusCode == 201
    outputs:
      containerId: $response.body#/Id
      warnings: $response.body#/Warnings
  - stepId: startContainer
    description: >-
      Start the container so the volume is actually mounted and the workload can
      begin writing to it.
    operationId: ContainerStart
    parameters:
    - name: id
      in: path
      value: $steps.createContainer.outputs.containerId
    successCriteria:
    - condition: $statusCode == 204
  - stepId: verifyMount
    description: >-
      Inspect the container to confirm the daemon reports the named volume mounted
      at the expected target path.
    operationId: ContainerInspect
    parameters:
    - name: id
      in: path
      value: $steps.createContainer.outputs.containerId
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.State.Running == true
      type: jsonpath
    outputs:
      mounts: $response.body#/Mounts
  - stepId: inspectVolume
    description: >-
      Read the volume back to capture its host mountpoint and usage data, which is
      what tells you whether it is in use or dangling.
    operationId: VolumeInspect
    parameters:
    - name: name
      in: path
      value: $inputs.volumeName
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      mountpoint: $response.body#/Mountpoint
      scope: $response.body#/Scope
      usageData: $response.body#/UsageData
  outputs:
    volumeName: $steps.createVolume.outputs.volumeName
    containerId: $steps.createContainer.outputs.containerId
    mountpoint: $steps.inspectVolume.outputs.mountpoint
    mounts: $steps.verifyMount.outputs.mounts