Added new endpoint to paginate a Workflow Run task_logs (#177)

* Merge changes from develop

* Removed invalid attribute from openapi definition and aded nullable field instead

* Added explicit deprecation warning on the task_log property

Author: patmagee

openapi/workflow_execution_service.openapi.yaml

@@ -398,6 +398,85 @@ paths:
               schema:
                 $ref: '#/components/schemas/ErrorResponse'
       deprecated: false
+  '/runs/{run_id}/tasks':
+    get:
+      tags:
+        - Workflow Runs
+      summary: ListTasks
+      description: >-
+        This endpoint provides a paginated list of tasks that were executed as part of a given
+        workflow run. Task ordering should be the same as what would be returned in a
+        `RunLog` response body.
+      operationId: ListTasks
+      parameters:
+        - name: run_id
+          in: path
+          description: ''
+          required: true
+          style: simple
+          schema:
+            type: string
+        - name: page_size
+          in: query
+          description: >-
+            OPTIONAL
+            The preferred number of task logs to return in a page.
+            If not provided, the implementation should use a default page size.
+            The implementation must not return more items
+            than `page_size`, but it may return fewer.  Clients should
+            not assume that if fewer than `page_size` items are
+            returned that all items have been returned.  The
+            availability of additional pages is indicated by the value
+            of `next_page_token` in the response.
+          style: form
+          explode: true
+          schema:
+            type: integer
+            format: int64
+        - name: page_token
+          in: query
+          description: >-
+            OPTIONAL
+            Token to use to indicate where to start getting results. If unspecified, return the first
+            page of results.
+          style: form
+          explode: true
+          schema:
+            type: string
+
+      responses:
+        200:
+          description: ''
+          headers: {}
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TaskListResponse'
+        401:
+          description: The request is unauthorized.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+        403:
+          description: The requester is not authorized to perform this action.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+        404:
+          description: The requested workflow run wasn't found.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+        500:
+          description: An unexpected error occurred.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+      deprecated: false
   '/runs/{run_id}/cancel':
     post:
       tags:
@@ -632,11 +711,20 @@ components:
           $ref: '#/components/schemas/State'
         run_log:
           $ref: '#/components/schemas/Log'
+        task_logs_url:
+          type: string
+          description: A reference to the complete url which may be used to obtain a paginated list of task logs for this workflow
         task_logs:
           type: array
+          deprecated: true
+          nullable: true
           items:
             $ref: '#/components/schemas/Log'
-          description: The logs, and other key info like timing and exit code, for each step in the workflow run.
+          description:  >-
+              The logs, and other key info like timing and exit code, for each step in the workflow run.
+              This field is deprecated and the `task_logs_url` should be used to retrieve a paginated list
+              of steps from the workflow run. This field will be removed in the next major version of the 
+              specification (2.0.0)
         outputs:
           type: object
           description: The outputs from the workflow run.
@@ -693,6 +781,21 @@ components:
             type: string
           description: an array of one or more acceptable types for the `workflow_type`
       description: Available workflow types supported by a given instance of the service.
+    TaskListResponse:
+      title: TaskListResponse
+      type: object
+      properties:
+        task_logs:
+          type: array
+          items:
+            $ref: '#/components/schemas/Log'
+          description: The logs, and other key info like timing and exit code, for each step in the workflow run.
+        next_page_token:
+          type: string
+          description: >-
+            A token which may be supplied as `page_token` in workflow run task list request to get the next page
+            of results.  An empty string indicates there are no more items to return.
+      description: The service will return a TaskListResponse when receiving a successful TaskListRequest.
     WorkflowEngineVersion:
       title: WorkflowEngineVersion
       type: object