api: add endpoint to retrieve output files

* Removes REANAFS singleton since it was making tests complicated.

Signed-off-by: Diego Rodriguez <diego.rodriguez@cern.ch>

docs/openapi.json

@@ -262,6 +262,73 @@
         "summary": "Adds a file to the workflow workspace."
       }
     },
+    "/api/workflows/{workflow_id}/workspace/outputs/{file_name}": {
+      "get": {
+        "description": "This resource is expecting a workflow UUID and a filename to return its content.",
+        "operationId": "get_workflow_outputs_file",
+        "parameters": [
+          {
+            "description": "Required. Organization which the worklow belongs to.",
+            "in": "query",
+            "name": "organization",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. UUID of workflow owner.",
+            "in": "query",
+            "name": "user",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. Workflow UUID.",
+            "in": "path",
+            "name": "workflow_id",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. Name of the file to be downloaded.",
+            "in": "path",
+            "name": "file_name",
+            "required": true,
+            "type": "string"
+          }
+        ],
+        "produces": [
+          "multipart/form-data"
+        ],
+        "responses": {
+          "200": {
+            "description": "Requests succeeded. The file has been downloaded.",
+            "schema": {
+              "type": "file"
+            }
+          },
+          "400": {
+            "description": "Request failed. The incoming data specification seems malformed."
+          },
+          "404": {
+            "description": "Request failed. User doesn't exist.",
+            "examples": {
+              "application/json": {
+                "message": "User 00000000-0000-0000-0000-000000000000 doesn't exist"
+              }
+            }
+          },
+          "500": {
+            "description": "Request failed. Internal controller error.",
+            "examples": {
+              "application/json": {
+                "message": "Either organization or user doesn't exist."
+              }
+            }
+          }
+        },
+        "summary": "Returns all workflows."
+      }
+    },
     "/api/yadage/remote": {
       "post": {
         "consumes": [

reana_workflow_controller/fsdb.py

@@ -25,19 +25,6 @@
 from fs import open_fs, path
 
 
-class REANAFS(object):
-    """REANA file system object."""
-
-    __instance = None
-
-    def __new__(cls):
-        """REANA file system object creation."""
-        if REANAFS.__instance is None:
-            with app.app_context():
-                REANAFS.__instance = open_fs(app.config['SHARED_VOLUME_PATH'])
-        return REANAFS.__instance
-
-
 def get_user_analyses_dir(org, user):
     """Build the analyses directory path for certain user and organization.
 
@@ -50,7 +37,7 @@ def get_user_analyses_dir(org, user):
 
 def create_user_space(user_id, org):
     """Create analyses directory for `user_id`."""
-    reana_fs = REANAFS()
+    reana_fs = open_fs(app.config['SHARED_VOLUME_PATH'])
     user_analyses_dir = get_user_analyses_dir(org, user_id)
     if not reana_fs.exists(user_analyses_dir):
         reana_fs.makedirs(user_analyses_dir)
@@ -68,7 +55,7 @@ def create_workflow_workspace(org, user, workflow_uuid):
     :param workflow_uuid: Analysis UUID.
     :return: Workflow and analysis workspace path.
     """
-    reana_fs = REANAFS()
+    reana_fs = open_fs(app.config['SHARED_VOLUME_PATH'])
     analysis_workspace = path.join(get_user_analyses_dir(org, user),
                                    workflow_uuid)
 

reana_workflow_controller/rest.py

@@ -26,7 +26,8 @@
 import traceback
 from uuid import uuid4
 
-from flask import Blueprint, abort, jsonify, request
+from flask import (Blueprint, abort, current_app, jsonify, request,
+                   send_from_directory)
 from werkzeug.utils import secure_filename
 
 from .factory import db
@@ -360,6 +361,94 @@ def seed_workflow_workspace(workflow_id):
         return jsonify({"message": str(e)}), 500
 
 
+@restapi_blueprint.route(
+    '/workflows/<workflow_id>/workspace/outputs/<file_name>', methods=['GET'])
+def get_workflow_outputs_file(workflow_id, file_name):  # noqa
+    r"""Get all workflows.
+
+    ---
+    get:
+      summary: Returns all workflows.
+      description: >-
+        This resource is expecting a workflow UUID and a filename to return
+        its content.
+      operationId: get_workflow_outputs_file
+      produces:
+        - multipart/form-data
+      parameters:
+        - name: organization
+          in: query
+          description: Required. Organization which the worklow belongs to.
+          required: true
+          type: string
+        - name: user
+          in: query
+          description: Required. UUID of workflow owner.
+          required: true
+          type: string
+        - name: workflow_id
+          in: path
+          description: Required. Workflow UUID.
+          required: true
+          type: string
+        - name: file_name
+          in: path
+          description: Required. Name of the file to be downloaded.
+          required: true
+          type: string
+      responses:
+        200:
+          description: >-
+            Requests succeeded. The file has been downloaded.
+          schema:
+            type: file
+        400:
+          description: >-
+            Request failed. The incoming data specification seems malformed.
+        404:
+          description: >-
+            Request failed. User doesn't exist.
+          examples:
+            application/json:
+              {
+                "message": "User 00000000-0000-0000-0000-000000000000 doesn't
+                            exist"
+              }
+        500:
+          description: >-
+            Request failed. Internal controller error.
+          examples:
+            application/json:
+              {
+                "message": "Either organization or user doesn't exist."
+              }
+    """
+    try:
+        user_uuid = request.args['user']
+        user = User.query.filter(User.id_ == user_uuid).first()
+        if not user:
+            return jsonify(
+                {'message': 'User {} does not exist'.format(user)}), 404
+
+        workflow = Workflow.query.filter(Workflow.id_ == workflow_id).first()
+        outputs_directory = os.path.join(
+            current_app.config['SHARED_VOLUME_PATH'],
+            workflow.workspace_path,
+            'outputs')
+        # fix, we don't know wich encoding is being used
+        # check how to add it to HTTP headers with `send_from_directory`
+        # or `send_file`
+        return send_from_directory(outputs_directory,
+                                   secure_filename(file_name),
+                                   mimetype='multipart/form-data',
+                                   as_attachment=True), 200
+
+    except KeyError:
+        return jsonify({"message": "Malformed request."}), 400
+    except Exception as e:
+        return jsonify({"message": str(e)}), 500
+
+
 @restapi_blueprint.route('/yadage/remote', methods=['POST'])
 def run_yadage_workflow_from_remote_endpoint():  # noqa
     r"""Create a new yadage workflow from a remote repository.

tests/test_views.py

@@ -28,6 +28,7 @@
 import uuid
 
 from flask import url_for
+from werkzeug.utils import secure_filename
 
 from reana_workflow_controller.fsdb import get_user_analyses_dir
 from reana_workflow_controller.models import Workflow, WorkflowStatus
@@ -173,3 +174,52 @@ def test_create_workflow_wrong_user(app, db_session, tmp_shared_volume_path):
             tmp_shared_volume_path,
             user_analyses_workspace)
         assert not os.path.exists(workflow_workspace)
+
+
+def test_get_workflow_outputs_file(app, db_session, default_user,
+                                   tmp_shared_volume_path):
+    """Test download output file."""
+    with app.test_client() as client:
+        # create workflow
+        organization = 'default'
+        data = {'parameters': {'min_year': '1991',
+                               'max_year': '2001'},
+                'specification': {'first': 'do this',
+                                  'second': 'do that'},
+                'type': 'cwl'}
+        res = client.post(url_for('api.create_workflow'),
+                          query_string={
+                              "user": default_user.id_,
+                              "organization": organization},
+                          content_type='application/json',
+                          data=json.dumps(data))
+
+        response_data = json.loads(res.get_data(as_text=True))
+        workflow_uuid = response_data.get('workflow_id')
+        workflow = Workflow.query.filter(
+            Workflow.id_ == workflow_uuid).first()
+        # create file
+        file_name = 'output name.csv'
+        file_binary_content = b'1,2,3,4\n5,6,7,8'
+        absolute_path_workflow_workspace = \
+            os.path.join(tmp_shared_volume_path,
+                         workflow.workspace_path)
+        # write file in the workflow workspace under `outputs` directory
+        file_path = os.path.join(absolute_path_workflow_workspace,
+                                 'outputs',
+                                 # we use `secure_filename` here because
+                                 # we use it in server side when adding
+                                 # files
+                                 secure_filename(file_name))
+        # because outputs directory doesn't exist by default
+        os.makedirs(os.path.dirname(file_path), exist_ok=True)
+        with open(file_path, 'wb+') as f:
+            f.write(file_binary_content)
+        res = client.get(
+            url_for('api.get_workflow_outputs_file', workflow_id=workflow_uuid,
+                    file_name=file_name),
+            query_string={"user": default_user.id_,
+                          "organization": organization},
+            content_type='application/json',
+            data=json.dumps(data))
+        assert res.data == file_binary_content