initial student commit

.dockerignore

+*
+
+!main.py
+
+!app
+!util
+
+!application.cfg
+!requirements.txt
+!uwsgi.ini

.gitignore

+
+# Created by https://www.gitignore.io/api/pycharm,python
+
+### PyCharm ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and Webstorm
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff:
+Pipfile
+.idea/
+
+# ignore data directory for local development
+data
+somedb.sqlite
+tests/somedb.sqlite
+
+# Gradle:
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Mongo Explorer plugin:
+.idea/**/mongoSettings.xml
+
+## File-based project format:
+*.iws
+
+## Plugin-specific files:
+
+# IntelliJ
+/out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+### PyCharm Patch ###
+# Comment Reason: https://github.com/joeblau/gitignore.io/issues/186#issuecomment-215987721
+
+# *.iml
+# modules.xml
+# .idea/misc.xml
+# *.ipr
+
+### Python ###
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+env/
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*,cover
+.hypothesis/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# dotenv
+.env
+
+# virtualenv
+.venv
+venv/
+ENV/
+
+# Spyder project settings
+.spyderproject
+
+# Rope project settings
+.ropeproject
+
+# End of https://www.gitignore.io/api/pycharm,python
+
+/coverage/

.gitlab-ci.yml

+image: lmmdock/build-environment
+
+stages:
+  - test
+  - build
+  - deploy
+
+before_script:
+  - mkdir -p build
+
+python-style:
+  stage: test
+  script:
+    - wget https://sre18.pages.rechenknecht.net/misc/pylintrc -O .pylintrc
+    - pip3 install -r requirements.txt
+    - pip3 install pylint
+    - pylint main.py app tests util
+
+python-test:
+  stage: test
+  script:
+    - pip3 install -r requirements.txt
+    - pip3 install coverage
+    - coverage run --branch --omit='tests/*','*/site-packages/*','*/dist-packages/*' -m unittest discover -p 'Test*.py'
+    - coverage html -d build/coverage
+    - coverage report
+  coverage: '/^TOTAL.*?(\d{1,3})%$/'
+  artifacts:
+    paths:
+      - build/coverage
+    expire_in: 1 week
+
+build-api-definition:
+  stage: build
+  image: node:10
+  script:
+    - yarn global add api2html
+    - mkdir -p build/api
+    - api2html docs/api-definition.yml -o build/api/index.html
+  artifacts:
+    paths:
+      - build/api
+    expire_in: 1 week
+
+pages:
+  stage: deploy
+  script:
+    - mkdir -p public
+    - cp -av build/api public/api
+  only:
+    - master
+  artifacts:
+    paths:
+      - public
+    expire_in: 1 week

Dockerfile

+FROM lmmdock/flask-webserver
+
+COPY ./ /app
+
+RUN pip3 install -r requirements.txt

README.md

+# Flask Training REST API
+This project contains a simple [Flask](http://flask.pocoo.org/) application.
+Flask is a Python based microframework to build small to mid sized applications and APIs.
+
+We wrote an OpenAPI v3 definition that defines the endpoint that should be implemented in this exercise.
+You can find the definition file in this repository at [docs/api-definition.yml](docs/api-definition.yml).
+We recommend to view the definition [here](https://www-technologien.pages.rechenknecht.net/flask-training-api-reference/api).
+
+## Quickstart
+We put a very basic implementation at [app/views_v1.py](app/views_v1.py). 
+Please clone this repository on your machine and complete the tasks given in the comments.
+Please have a look at [docs/api-definition.yml](docs/api-definition.yml) for a definition of the endpoints that should be implemented.
+
+## Tasks
+In this assignment we will build a REST API which serves pictures with metadata from a DB.
+These pictures we feed into the DB by ourself by allowing clients to call `v1/images/fetch` method.
+
+To have some data to play with, we are using a freely available image set normally used for Deep Learning you can find [here](https://image-annotations.marschke.me/NAACL/).
+
+You are supposed to perform the following tasks:
+
+1. Read this README and make sure you understand it
+1. Look into the code, understand what it is doing in general
+1. Answer questions stated in `get_answers` in [app/views_v1.py](app/views_v1.py)
+1. Implement the API itself by looking at https://www-technologien.pages.rechenknecht.net/flask-training-api-reference/api or using the API definition directly: [docs/api-definition.yml](docs/api-definition.yml)
+    1. Make sure you understood the concept of routes and Blueprints / API-Versioning by Paths
+    1. Try to run the API and test it with a simple request (such as the curl request below)
+    1. We suggest you to start with the `/images/fetch` route because it will get the data into your DB
+    1. Implement other get requests, most simple one is the request for one image. To get image data from database check out the Peewee documentation.
+1. Hand in your solution as stated in the route `/v1/answers` 
+
+## Getting started
+This repository contains a generic Flask REST API framework, which contains mainly the Flask library itself and some other helpful tools.
+One of these tools is the Flask wrapper, which takes care of helpful error messages in case of a program failure (500 Server Error) and provides some cool additional features to deal with new web security stuff such as CORS (check it out ;) ).
+
+**Please check out [this guide](https://blog.philipphauer.de/restful-api-design-best-practices/) for best practices in RESTful API design.**
+
+You will also find an Object to Relational Mapping (ORM) library named [Peewee](http://docs.peewee-orm.com/en/latest/) to handle connections to our database. If you are not familiar with an ORM you should check out [this neat guide](https://stackoverflow.com/questions/1279613/what-is-an-orm-and-where-can-i-learn-more-about-it#answer-1279678).
+Because we were lazy people we created a little wrapper for Peewee as well, which makes some integration into Flask a little bit easier.
+Therefore to access the database object you have to import the `database_holder` from `app` to access the database object itself.
+You need this for doing cool things like
+```python
+with database_holder.database.transaction():
+    image_object = Image(someProp='someValue').save()
+    
+    # Here could arise an Exception in case of program failure
+    # If it is breaking here, all actions done in the transaction will be reverted by the DBMS.
+    # So you will not get a state, which is invalid. 
+    
+    Caption(someOtherProp='someValue', image=image_object)
+```
+
+We recommend you to use an IDE like PyCharm for developing this piece of software.
+If you are not familiar with IDEs in general you should use this project as a starting point.
+Trust us, you will have many (Python) projects where a nice IDE is a real gamechanger.
+
+## Development setup
+You have to set the correct PythonPath when executing the tests to the base directory of this project.
+The PythonPath is the base path for the Python interpreter, which is used for resolving imports.
+When you are executing the `run.py` file from the project root, you most likely will not have to modify your PythonPath.
+
+In order to execute this project, you have to have a recent Python Interpreter (we recommend at least Python 3.6, 3.5 should work as well, Python 2 is not working) with pip (normally installed along).
+Also you have to install all the project requirements stated in `requirements.txt`.
+You can do so by executing `pip3 install -r requirements.txt` in your project folder.
+
+Please take note that you will use `lxml` later on in the project.
+`lxml` is a Python wrapper for `libxml`, which allows you to parse XML files easily.
+Therefore you may have to install the `lxml` library on your system (on Linux and Mac, Windows is using a static build provided by pip).
+Check out [this](https://lxml.de/installation.html) website how to install `lxml` on your system (Mac and Linux).
+
+This project contains a lot of stub code, so you will not have to understand all code in it.
+For your assignments a good starting point should be the file `app/views_v1.py`, which contains the route definitions.
+Also you should check out the directory `app/models` where you can find all of the Database models we use.
+Because we are no Database lecture we defined the models for you.
+But probably it is important to you to understand how foreign keys work and why they exist.
+
+In our case you can navigate through the foreign keys from one side by accessing `image` and from the other through the `backref` `captions`.
+
+Pro tip: We recommend you to use a Python venv (check this out), but it should work "native" as well.
+
+## Run the API
+To run the API simply execute `python3 run.py` in project root.
+
+After successful starting (you should see something like this in your terminal):
+
+```
+* Serving Flask app "app" (lazy loading)
+* Environment: production
+WARNING: Do not use the development server in a production environment.
+Use a production WSGI server instead.
+* Debug mode: off
+```
+
+you can access your API for example by the following command:
+
+```bash
+curl http://localhost:5000/v1/tasks
+```
+
+### Manual testing
+You can access your API with almost every HTTP client on your PC.
+For an easy way to test different operations (POST, GET, PUT, PATCH) we recommend to use [Postman](https://www.getpostman.com/) (or simply write tests ;) ),
+
+### Executing tests
+Try `python3 -m unittest discover -p 'Test*.py'` after setting up your development environment.
+
+If you are using PyCharm you can use the built in test environment as well.
+Just add a new run config `Python tests` -> `unittest` pointing to the test directory of this project.
+As a pattern please provide `Test*.py` because we do not use the standard pattern for our tests.
+
+## Writing tests
+We do not require you but encourage you to write tests for your application. You can do so by adding methods beginning with `test_` in `tests/TestBlueprintV1.py`.
+
+We are using the `flask_testing` [framework](https://github.com/jarus/flask-testing) to execute our tests - just in case you want a reference.
+
+### Linter
+If you are really ambitious you can run `pylint` with our own flavour.
+Because you are so ambitious you can pick up the command right from our `.gitlab-ci.yml`, which we are using normally for all our projects.
+
+### GitLab
+Just in case you want to use the automated test and linter feature you have to upload the code simply to a GitLab instance with a configured worker on it.
+
+## Docker
+The following section is just for your information. You do not have to use Docker or understand it at all (at this moment).
+
+We provide a simple Docker file for you, which should have all features you need.
+If you think it would be better to use another Docker base you can surely do it as long as you ensure that you expose your web server on port `8080`.
+
+You can build the Docker container by executing `docker build .` (you should define `--tag=someTag` to use the image later on).
+
+If you are new to Docker, please check out [this](https://docs.docker.com/get-started/) little guide which explains the core concepts (you only need part 1 and 2).
+Also you should get information about how to build a Docker container.
+
+Please make sure you can build the Docker container before handing in your solution.
+We will grade the software in the container and because you want to get some credits for this assignment you should make sure that we can build the container right off.
+
+## Ok, I really do not know what I am supposed to do
+If you have any questions left or found a bug in our stub code, please mail us at `www-coding@lists.myhpi.de`.
+We will be happy to help you.

app/__init__.py

+from flask_common.flask import Flask
+from flask_common.util import register_cors_headers
+from peewee_common.Database import Holder
+
+
+flask = Flask(__name__)
+flask.config.from_pyfile("../application.cfg")
+
+database_holder = Holder(flask)
+
+from app.models import Image, Caption
+
+database_holder.database.create_tables([Image, Caption])
+
+from app.views_v1 import BASE
+from app.views_v1 import V1
+
+flask.register_blueprint(BASE)
+flask.register_blueprint(V1)
+
+register_cors_headers(flask, allowOrigin=lambda _: True, allowCredentials=False,
+                      allowedHeaders='Content-Type,cache-control,x-requested-with')

app/models/Caption.py

+import datetime
+
+from peewee import CharField, DateTimeField, ForeignKeyField
+
+from app import database_holder
+from app.models import Image
+
+
+class Caption(database_holder.Model):
+    creation_date = DateTimeField(default=datetime.datetime.now)
+
+    # Anticipating that a caption is not longer than 255 chars
+    text = CharField()
+
+    # Be careful: on_delete is not working for SQLite, which we are using
+    image = ForeignKeyField(Image, backref="captions", on_delete='CASCADE')

app/models/Image.py

+import datetime
+
+from peewee import CharField, DateTimeField
+
+from app import database_holder
+
+
+class Image(database_holder.Model):
+    # time received on api
+    creation_date = DateTimeField(default=datetime.datetime.now)
+
+    # be cautious when storing large strings in here, they probably get shortened
+    src = CharField()
+
+    category = CharField()

app/models/__init__.py

+from .Image import Image
+from .Caption import Caption

app/views_v1.py

+# Remove for testing with pylint ;)
+# pylint: disable=fixme
+
+# **It took me ? hours to solve this assignment.**
+# Solved by (Matrikelnummern): Person 1, Person 2
+
+
+import json
+import re
+
+from lxml import html
+
+import requests
+from flask import Blueprint, request, Response
+
+from app import database_holder
+
+from app.models import Image, Caption
+
+BASE = Blueprint('', __name__, url_prefix='')
+V1 = Blueprint('v1', __name__, url_prefix='/v1')
+
+BASE_URL_DATASET = 'https://image-annotations.marschke.me/NAACL/'
+
+
+@V1.route('/health', methods=['GET'])
+@BASE.route('/health', methods=['GET'])  # This route exists for the health check of the docker container
+def check_health():
+    return json.dumps({
+        "status": "up",
+        "message": "operational",
+    }), 200
+
+
+def get_image_json_object(image):
+    caption_list = []
+
+    for caption in image.captions:
+        caption_list.append({
+            'text': caption.text
+        })
+    return {
+        'id': image.id,
+        'category': image.category,
+        'captions': caption_list,
+    }
+
+
+@V1.route('/tasks', methods=['GET'])
+def get_tasks():
+    return json.dumps({
+        'taskList': [
+            'Answer questions stated in get_answers() (5 Points)',
+            'Build API defined in docs/api-definition.yml (precise as possible) (23 Points)',
+        ]
+    })
+
+
+# 2 Points code style:
+#   Linter (each "real" error -0.5)
+#   Readability (up to -2 if very "obfuscated")
+#
+# Bonus points for really nice solutions and approaches, which aren't covered by our solution / in our opinion nicer
+# than in our solution
+
+@V1.route('/answers', methods=['GET'])
+def get_answers():
+    return json.dumps({
+        'Is a REST API bound to a single exchange format like JSON? How can multiple formats be used? (1 Point)':
+            '',
+        'Are all operations on this REST APIs idempotent? Explain why! (1 Point)':
+            '',
+        'Why could it be problematic to work with full URLs as links? Name and explain two reasons (2 Points)': [
+            '',
+        ],
+        'Hand in requirements (1 Point)': [
+            'ZIP the complete source code directly from the root directory (so no useless subdirs in ZIP please)',
+            'Make an own solution, show us that this is your solution by adding comments where they are needed to '
+            'understand your source code',
+            'Do not change any file names if not really needed (and then please document).',
+            'Do not alter return definitions from functions get_tasks and get_answers.',
+            'Write your answers in German or English, in code please write all English.',
+            'Please write down your matriculation number at top of this file.',
+            'Please add a comment at top of this file how much time you needed for this assignment (please be honest).',
+        ]
+    })
+
+
+# TODO implement missing routes
+# You can request images from the database by executing something like
+# for image in Image.select().limit(limit).offset(offset):
+#     do something with the image
+#
+# To access captions, you need to access image.captions for a list of all caption object (more precisely a generator)
+#
+# For counting all images in DB you can use this command: Image.select().count()
+# If using pylint please add # pylint: disable=no-value-for-parameter to the end of the line.
+#
+# You can access GET arguments by request.args.get('key', 'default') where request is a global object defined by Flask
+
+
+@V1.route('/images/fetch', methods=['POST'])
+def update_image_storage():
+    """This operation should clear DB if run multiple times on the same DB
+
+    8 Points: 3 for xpath (1 each), 1 for correct resource GET, 1 for correct DB cleaning, 1 for correct DB saving,
+              2 for correct regex, 2 for Transaction explanation
+    -0.5 for small mistakes (return value...)
+
+    :return: json if successful or not
+    """
+
+    # TODO get BASE_URL_DATASET, we would suggest requests for it (already installed) Think about error handling.
+    answer = requests.get(BASE_URL_DATASET)
+    # Error handling
+
+    # TODO Please explain what this line is doing. Why is it needed? In which case? (directly here as comment)
+    with database_holder.database.transaction():
+        # Empty databases
+        Image.delete().execute()  # pylint: disable=no-value-for-parameter
+        Caption.delete().execute()  # pylint: disable=no-value-for-parameter
+
+        # TODO We encourage you to use the html.fromstring method provided by the lxml package (already installed).
+        tree = None
+
+        # TODO After parsing the XML tree, please use the xpath method to iterate over all elements
+        for pictureTree in tree.xpath(''):
+
+            # TODO get image src by xpath method, you can check lxml documentation or use a debugger to find attributes
+            src = None
+
+            # TODO parse category by appling a regex to src, probably check out regex101.com
+            # check out re docs of Python3
+            category = None
+
+            # save Image in DB, nothing magical here
+            imageDb = Image(src=src, category=category)
+            imageDb.save()
+
+            # TODO iterate over all captions by using xpath method. Try to make the xpath expression as short as
+            # possible
+            for captionTree in []:
+                caption_text = ''
+                Caption(text=caption_text, image=imageDb).save()
+
+    return json.dumps({'status': 'finished'}), 200

application.cfg

+DATABASE = {
+    'name': "somedb.sqlite",
+    'engine': 'peewee.SqliteDatabase',
+}
+
+COOKIE_AES_KEY = 'CHANGEME'

docs/api-definition.yml

+openapi: "3.0.0"
+info:
+  description: "This is the API definition for the Flask Training API."
+  version: "1.0.0"
+  title: "Flask Training API"
+  contact:
+    email: "leonard@marschke.me"
+servers:
+  - url: "https://someserver/v1"
+
+paths:
+  /health:
+    get:
+      summary: Gets service health
+      responses:
+        200:
+          description: Service operational
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/HealthResponse'
+        503:
+          description: Service not operational
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/HealthResponse'
+        default:
+          $ref: '#/components/responses/Error'
+
+  /images:
+    get:
+      summary: Get saved images
+      description: To use pagination check out query parameters.
+      parameters:
+        - name: limit
+          in: query
+          description: Limits the response size, defaults to 100, minimum 1, maximum 500
+          schema:
+            type: integer
+            minimum: 1
+            default: 100
+            maximum: 500
+            description: Maximal number of images
+        - name: offset
+          in: query
+          description: Skips the beginning of the sorted response
+          schema:
+            type: integer
+            minimum: 0
+            default: 0
+            description: Number of images to skip
+      responses:
+        200:
+          description: Mail content
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  images:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Image'
+                  count:
+                    type: number
+                    format: uint
+                    description: Count of all images available
+        400:
+          $ref: '#/components/responses/InvalidArgument'
+        default:
+          $ref: '#/components/responses/Error'
+
+  /images/{imageId}:
+    get:
+      summary: Get metadata of image
+      parameters:
+        - $ref: '#/components/parameters/ImageId'
+      responses:
+        200:
+          description: Mail metadata
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  image:
+                    $ref: '#/components/schemas/Image'
+        404:
+          $ref: '#/components/responses/NotFound'
+        default:
+          $ref: '#/components/responses/Error'
+
+  /images/{imageId}/bitmap:
+    get:
+      summary: Get bitmap of image
+      parameters:
+        - $ref: '#/components/parameters/ImageId'
+      responses:
+        200:
+          description: Bitmap
+          content:
+            image:
+              schema:
+                type: string
+                format: binary
+                description: Image bitmap
+        404:
+          $ref: '#/components/responses/NotFound'
+        default:
+          $ref: '#/components/responses/Error'
+
+  /images/fetch:
+    post:
+      summary: Fetches image DB
+      description: Should fetch images from https://image-annotations.marschke.me/NAACL/. Operation must be idempotent.
+      responses:
+        200:
+          description: Mail successfully saved
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  status:
+                    type: string
+                    description: Finish status
+                    example: 'finished'
+        default:
+          $ref: '#/components/responses/Error'
+
+
+
+components:
+  schemas:
+    HealthResponse:
+      type: object
+      properties:
+        status:
+          type: string
+          description: Current status of the service
+        message:
+          type: string
+          description: Explaining the current status
+    Error:
+      type: object
+      properties:
+        message:
+          type: string
+          description: the error message
+    Image:
+      type: object
+      properties:
+        id:
+          type: number
+          format: uint
+          example: 30
+        category:
+          type: string
+          description: Category of image
+          example: 'somecategory'
+        captions:
+          type: array
+          description: Captions for this image
+          items:
+            type: object
+            properties:
+              text:
+                type: string
+                description: Caption text
+
+  responses:
+    Error:
+      description: Unknown Error
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+    InvalidArgument:
+      description: Invalid argument passed, see message field for more information.
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+    NotFound:
+      description: Not found
+      content: