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

Create an .env file:

SECRET_KEY=46-2346-24986-2384632-2039845-24
SERVER_NAME=$HOST:5000

Let docker do the rest of the work:

$ docker-compose up -d

Here's a sneak peak at the different services:

$ docker-compose ps
Name                        Command               State                       Ports
------------------------------------------------------------------------------------------------------------------
flaskbones_app_1           make server                      Up      0.0.0.0:5000->5000/tcp
flaskbones_celery_1        make celery                      Up
flaskbones_db_1            /docker-entrypoint.sh postgres   Up      0.0.0.0:5432->5432/tcp
flaskbones_mailcatcher_1   mailcatcher --smtp-ip=0.0. ...   Up      0.0.0.0:1025->1025/tcp, 0.0.0.0:1080->1080/tcp
flaskbones_memcached_1     /entrypoint.sh memcached         Up      0.0.0.0:11211->11211/tcp
flaskbones_redis_1         /entrypoint.sh redis-server      Up      0.0.0.0:6379->6379/tcp

1. Install required services:

   $ brew install memcached
   $ brew install redis
   $ brew install postgresql
   $ gem install mailcatcher
   

2. Install Python packages:

   $ make init
   

3. Set necessary environment variables:

   $ export SECRET_KEY=46-2346-24986-2384632-2039845-24
   $ export DATABASE_URL=postgresql://$USER@localhost/flask_bones
   $ export SERVER_NAME=$HOST:5000
   

4. Install Javascript dependencies:

   $ make assets
   

5. Setup database and seed with test data:

   $ make db
   

6. Run a local SMTP server:

   $ mailcatcher
   

7. Run the celery worker:

   $ make celery
   

8. Run local server:

   $ make server
   

1. Caching with Memcached

   from app.extensions import cache
   
   # cache something
   cache.set('some_key', 'some_value')
   
   # fetch it later
   cache.get('some_key')

2. Email delivery

   from app.extensions import mail
   from flask.ext.mail import Message
   
   # build an email
   msg = Message('User Registration', sender='admin@flask-bones.com', recipients=[user.email])
   msg.body = render_template('mail/registration.mail', user=user, token=token)
   
   # send
   mail.send(msg)

3. Asynchronous job scheduling with Celery & Redis

   from app.extensions import celery
   
   # define a job
   @celery.task                                                                     
   def send_email(msg):                                                             
       mail.send(msg) 
   
   # queue job
   send_email.delay(msg)

4. 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()

5. 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')

6. 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)

7. Form validation & CSRF protection with WTForms

   # place a csrf token on a form
   {{ form.csrf_token }}
   
   # then validate
   form.validate_on_submit()

8. Scale with Blueprints

   # app/user/__init__.py
   user = Blueprint('user', __name__, template_folder='templates')
   
   # app/__init__.py
   app = Flask(__name__)
   app.register_blueprint(user, url_prefix='/user')

9. Automated tests

   # run the test suite
   python tests.py

10. Use any relational database using the SQLAlchemy ORM

```bash
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)
```

11. Merge and compress your javascripts and stylesheets

    # create a bundle of assets
    js = Bundle(
        'js/jquery.js',
        'js/bootstrap.min.js',
        filters='jsmin',
        output='gen/packed.js'
    )

    # serve up a single minified file
    {% assets "js_all" %}
        <script type="text/javascript" src="{{ ASSET_URL }}"></script>
    {% endassets %}

12. Version your database schema

    # Display the current revision
    $ dcr app python manage.py db current
    1fb7c6da302 (head)
    
    # Create a new migration
    $ dcr app python manage.py db revision
    
    # Upgrade the database to a later version
    $ dcr app python manage.py db upgrade

13. 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 i81n/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