flask-bones

An example of a large scale Flask application using blueprints and extensions.

Setup

Quickly run the project using docker and docker-compose:

docker-compose up -d

Create the database and seed it with some data:

docker-compose run --rm app flask create-db
docker-compose run --rm app flask populate-db --num_users 5

Download front-end dependencies with yarn:

yarn install --modules-folder ./app/static/node_modules

Configuration

The following environment variables are optional:

Name	Purpose
APP_NAME	The name of the application. i.e Flask Bones
MAIL_PORT	The port number of an SMTP server.
MAIL_SERVER	The hostname of an SMTP server.
MEMCACHED_HOST	The hostname of a memcached server.
MEMCACHED_PORT	The port number of a memcached server.
POSTGRES_HOST	The hostname of a postgres database server.
POSTGRES_PASS	The password of a postgres database user.
POSTGRES_PORT	The port number of a postgres database server.
POSTGRES_USER	The name of a postgres database user.
REDIS_HOST	The hostname of a redis database server.
REDIS_PORT	The port number of a redis database server.
SECRET_KEY	A secret key required to provide authentication.
SERVER_NAME	The hostname and port number of the server.

Features

Caching with Memcached

from app.extensions import cache

# Cache something
cache.set('some_key', 'some_value')

# Fetch it later
cache.get('some_key')

Email delivery

from app.extensions import mail
from flask_mail import Message

# Build an email
msg = Message('User Registration', sender='[email protected]', recipients=[user.email])
msg.body = render_template('mail/registration.mail', user=user, token=token)

# Send
mail.send(msg)

Asynchronous job scheduling with RQ

RQ is a simple job queue for python backed by redis.

Define a job:

@rq.job
def send_email(msg):
    mail.send(msg)

Start a worker:

flask rq worker

Queue the job for processing:

send_email.queue(msg)

Monitor the status of the queue:

flask rq info --interval 3

For help on all available commands:

flask rq --help

Stupid simple user management

from app.extensions import login_user, logout_user, login_required

# Login user
login_user(user)

# You now have a global proxy for the user
current_user.is_authenticated

# Secure endpoints with a decorator
@login_required

# Log out user
logout_user()

Password security that can keep up with Moores Law

from app.extensions import bcrypt

# Hash password
pw_hash = bcrypt.generate_password_hash('password')

# Validate password
bcrypt.check_password_hash(pw_hash, 'password')

Easily swap between multiple application configurations

from app.config import dev_config, test_config

app = Flask(__name__)

class dev_config():
    DEBUG = True

class test_config():
    TESTING = True

# Configure for testing
app.config.from_object(test_config)

# Configure for development
app.config.from_object(dev_config)

Form validation & CSRF protection with WTForms

Place a csrf token on a form:

{{ form.csrf_token }}

Validate it:

form.validate_on_submit()

Rate-limit routes

from app.extensions import limiter

@limiter.limit("5 per minute")
@auth.route('/login', methods=['GET', 'POST'])
def login():
    # ...
    return 'your_login_page_contents'

Automated tests

Run the test suite:

pytest

Use any relational database using the SQLAlchemy ORM

from app.user.models import User

# Fetch user by id
user = User.get_by_id(id)

# Save current state of user
user.update()

# Fetch a paginated set of users
users = User.query.paginate(page, 50)

Front-end asset management

Download front-end dependencies with yarn:

yarn install --modules-folder ./app/static/node_modules

Merge and compress them together with Flask-Assets:

flask assets build

Version your database schema

Display the current revision:

flask db current

Create a new migration:

flask db revision

Upgrade the database to a later version:

flask db upgrade

Internationalize the application for other languages (i18n)

Extract strings from source and compile a catalog (.pot):

pybabel extract -F babel.cfg -o i18n/messages.pot .

Create a new resource (.po) for German translators:

pybabel init -i i18n/messages.pot -d i18n -l de

Compile translations (.mo):

pybabel compile -d i18n

Merge changes into resource files:

pybabel update -i i18n/messages.pot -d i18n