When I released bull as an open source project, it was in quite a state. Everything was in a single file, there was inline HTML (ew), and both tests and documentation were non-existent. Over the past week, I've spent some time "productionizing" bull , and recounting the steps I took will likely be helpful to others looking to deploy a Flask app to production. In this article, you'll learn how to organize a Flask application, add testing and documentation, and even how to enable authentication for "admin-only" content.

bull looks like a pile of...

The first git push of bull was a crazy mess, but it worked, and that's all I was concerned with at the time. I knew I would clean everything up "later", so I wasn't worried about the quality at that time. Besides, anyone capable of using bull in that state was certainly capable of cleaning it up a bit on their own, if they so desired.

To make it more accessible, however, it needed an overhaul. By focusing on a few key areas, I was able to make bull a solid, production-ready application. Those areas included:

Project layout An "admin" work flow with restricted pages Automated testing Automated documentation generation

I'll discuss each of these sections in detail, as I'm convinced that, if you get these areas right, you're 90% of the way to having a production-ready application.

Everything in its place

bull was comprised of a single app.py file with all code, templates, and database models. The first step was simple: organize the code along MVC lines. That meant the models got their own file ( models.py ), the controllers/application logic got a file (it became bull.py ), and the views/templates were moved into a separate directory and implemented as proper Jinja2 templates (in the templates directory, the default location Flask looks for template files).

Here was the contents of models.py :

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 """Database models for the Bull application.""" import datetime from flask.ext.sqlalchemy import SQLAlchemy db = SQLAlchemy () class Product ( db . Model ): """A digital product for sale on our site. :param int id: Unique id for this product :param str name: Human-readable name of this product :param str file_name: Path to file this digital product represents :param str version: Optional version to track updates to products :param bool is_active: Used to denote if a product should be considered for-sale :param float price: Price of product """ __tablename__ = 'product' id = db . Column ( db . Integer , primary_key = True , autoincrement = True ) name = db . Column ( db . String ) file_name = db . Column ( db . String ) version = db . Column ( db . String , default = None , nullable = True ) is_active = db . Column ( db . Boolean , default = True , nullable = True ) price = db . Column ( db . Float ) def __str__ ( self ): """Return the string representation of a product.""" if self . version is not None : return '{} (v{})' . format ( self . name , self . version ) return self . name class Purchase ( db . Model ): """Contains information about the sale of a product. :param str uuid: Unique ID (and URL) generated for the customer unique to this purchase :param str email: Customer's email address :param int product_id: ID of the product associated with this sale :param product: The associated product :param downloads_left int: Number of downloads remaining using this URL """ __tablename__ = 'purchase' uuid = db . Column ( db . String , primary_key = True ) email = db . Column ( db . String ) product_id = db . Column ( db . Integer , db . ForeignKey ( 'product.id' )) product = db . relationship ( Product ) downloads_left = db . Column ( db . Integer , default = 5 ) sold_at = db . Column ( db . DateTime , default = datetime . datetime . now ) def sell_date ( self ): return self . sold_at . date () def __str__ ( self ): """Return the string representation of the purchase.""" return '{} bought by {}' . format ( self . product . name , self . email )

You'll notice that there's a lot of documentation/docstrings in there, and that's another part of the production-puzzle. Adding documentation that Sphinx will be able to make sense of and use to generate pretty HTML/PDF output is key. Obviously, writing the documentation as you go is easier and more productive than retro-fitting existing code with documentation, but I had to do a bit of the latter here.

bull.py contained all of the "controller" logic for the application. It looked like this:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 """Bull is a library used to sell digital products on your website. It's meant to be run on the same domain as your sales page, making analytics tracking trivially easy. """ import logging import sys import uuid from collections import defaultdict from flask import ( Blueprint , send_from_directory , abort , request , render_template , current_app , render_template , redirect , url_for ) from flask.ext.sqlalchemy import SQLAlchemy from flask.ext.mail import Mail , Message import stripe from .models import Product , Purchase , User , db logger = logging . getLogger ( __name__ ) bull = Blueprint ( 'bull' , __name__ ) mail = Mail () @bull.route ( '/<purchase_uuid>' ) def download_file ( purchase_uuid ): """Serve the file associated with the purchase whose ID is *purchase_uuid*. :param str purchase_uuid: Primary key of the purchase whose file we need to serve """ purchase = Purchase . query . get ( purchase_uuid ) if purchase : purchase . downloads_left -= 1 if purchase . downloads_left <= 0 : return render_template ( 'downloads_exceeded.html' ) db . session . commit () return send_from_directory ( directory = current_app . config [ 'FILE_DIRECTORY' ], filename = purchase . product . file_name , as_attachment = True ) else : abort ( 404 ) @bull.route ( '/buy' , methods = [ 'POST' ]) def buy (): """Facilitate the purchase of a product.""" stripe_token = request . form [ 'stripeToken' ] email = request . form [ 'stripeEmail' ] product_id = request . form [ 'product_id' ] product = Product . query . get ( product_id ) amount = int ( product . price * 100 ) try : charge = stripe . Charge . create ( amount = amount , currency = 'usd' , card = stripe_token , description = email ) except stripe . CardError : return render_template ( 'charge_error.html' ) current_app . logger . info ( charge ) purchase = Purchase ( uuid = str ( uuid . uuid4 ()), email = email , product = product ) db . session . add ( purchase ) db . session . commit () mail_html = render_template ( 'email.html' , url = purchase . uuid , ) message = Message ( html = mail_html , subject = current_app . config [ 'MAIL_SUBJECT' ], sender = current_app . config [ 'MAIL_FROM' ], recipients = [ email ]) with mail . connect () as conn : conn . send ( message ) return render_template ( 'success.html' , url = str ( purchase . uuid ), purchase = purchase , product = product , amount = amount ) @bull.route ( '/reports' ) def reports (): """Run and display various analytics reports.""" products = Product . query . all () purchases = Purchase . query . all () purchases_by_day = defaultdict ( lambda : { 'units' : 0 , 'sales' : 0.0 }) for purchase in purchases : purchase_date = purchase . sold_at . date () . strftime ( '%m- %d ' ) purchases_by_day [ purchase_date ][ 'units' ] += 1 purchases_by_day [ purchase_date ][ 'sales' ] += purchase . product . price purchase_days = sorted ( purchases_by_day . keys ()) units = len ( purchases ) total_sales = sum ([ p . product . price for p in purchases ]) return render_template ( 'reports.html' , products = products , purchase_days = purchase_days , purchases = purchases , purchases_by_day = purchases_by_day , units = units , total_sales = total_sales ) @bull.route ( '/test/<product_id>' ) def test ( product_id ): """Return a test page for live testing the "purchase" button. :param int product_id: id (primary key) of product to test. """ test_product = Product . query . get ( product_id ) return render_template ( 'test.html' , test_product = test_product )

You'll notice that bull is a Blueprint rather than a "normal" Flask application. This allows bull to be added to existing Flask applications without disruption (a Blueprint in Flask is a "pattern" for creating mini, application-like things like bull ). You may also notice that there's an endpoint that wasn't present in the original version: /reports . I wanted to enable simple analytics in bull , and that's what the /reports endpoint represents.

Lock-down

At this point, you may be thinking, "but can't anyone go to the /reports endpoint and see your sales numbers?" Yep. And that obviously won't do. What we need is a way to allow only authorized users to hit that endpoint. This means we'll need to create a user model and deal with all sorts of nasty things like a sign-up work-flow, password generation and storage (easy to get wrong), and forms. In the interest of me doing as little work as possible, I made use of some of Flask's great extensions.

I decided to use Flask-Login for authorization. It gives you a @login_required decorator you can toss in front of sensitive endpoints. It doesn't handle, however, registration.

Knowing that registration can be a bit of a rabbit hole (and, again, wanting to minimize the amount of effort I put into this), I decided that, rather than have a web-based registration work-flow, I would simply include a script to create an admin user, since in almost all cases a single admin user would suffice. That meant, however, creating a User model and making some changes to the application logic. The final models.py became the following:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 """Database models for the Bull application.""" import datetime from flask.ext.sqlalchemy import SQLAlchemy db = SQLAlchemy () class Product ( db . Model ): """A digital product for sale on our site. :param int id: Unique id for this product :param str name: Human-readable name of this product :param str file_name: Path to file this digital product represents :param str version: Optional version to track updates to products :param bool is_active: Used to denote if a product should be considered for-sale :param float price: Price of product """ __tablename__ = 'product' id = db . Column ( db . Integer , primary_key = True , autoincrement = True ) name = db . Column ( db . String ) file_name = db . Column ( db . String ) version = db . Column ( db . String , default = None , nullable = True ) is_active = db . Column ( db . Boolean , default = True , nullable = True ) price = db . Column ( db . Float ) def __str__ ( self ): """Return the string representation of a product.""" if self . version is not None : return '{} (v{})' . format ( self . name , self . version ) return self . name class Purchase ( db . Model ): """Contains information about the sale of a product. :param str uuid: Unique ID (and URL) generated for the customer unique to this purchase :param str email: Customer's email address :param int product_id: ID of the product associated with this sale :param product: The associated product :param downloads_left int: Number of downloads remaining using this URL """ __tablename__ = 'purchase' uuid = db . Column ( db . String , primary_key = True ) email = db . Column ( db . String ) product_id = db . Column ( db . Integer , db . ForeignKey ( 'product.id' )) product = db . relationship ( Product ) downloads_left = db . Column ( db . Integer , default = 5 ) sold_at = db . Column ( db . DateTime , default = datetime . datetime . now ) def sell_date ( self ): return self . sold_at . date () def __str__ ( self ): """Return the string representation of the purchase.""" return '{} bought by {}' . format ( self . product . name , self . email ) class User ( db . Model ): """An admin user capable of viewing reports. :param str email: email address of user :param str password: encrypted password for the user """ __tablename__ = 'user' email = db . Column ( db . String , primary_key = True ) password = db . Column ( db . String ) authenticated = db . Column ( db . Boolean , default = False ) def is_active ( self ): """True, as all users are active.""" return True def get_id ( self ): """Return the email address to satisfy Flask-Login's requirements.""" return self . email def is_authenticated ( self ): """Return True if the user is authenticated.""" return self . authenticated def is_anonymous ( self ): """False, as anonymous users aren't supported.""" return False

The methods is_active , get_id , is_authenticated , and is_anonymous are required by Flask-login and are quite straightforward for our purposes. User.authenticated represents whether or not the user is currently authenticated (and thus changes after login/logout).

The changes to bull.py were a bit more involved, but still quite simple. Here's the final version of that file:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 """Bull is a library used to sell digital products on your website. It's meant to be run on the same domain as your sales page, making analytics tracking trivially easy. """ import logging import sys import uuid from collections import defaultdict from flask import ( Blueprint , send_from_directory , abort , request , render_template , current_app , render_template , redirect , url_for ) from flaskext.bcrypt import Bcrypt from flask.ext.sqlalchemy import SQLAlchemy from flask.ext.login import LoginManager , login_required , login_user , logout_user , current_user from flask.ext.mail import Mail , Message from flask_wtf import Form from wtforms import TextField , PasswordField from wtforms.validators import DataRequired import stripe from .models import Product , Purchase , User , db logger = logging . getLogger ( __name__ ) bull = Blueprint ( 'bull' , __name__ ) mail = Mail () login_manager = LoginManager () bcrypt = Bcrypt () class LoginForm ( Form ): """Form class for user login.""" email = TextField ( 'email' , validators = [ DataRequired ()]) password = PasswordField ( 'password' , validators = [ DataRequired ()]) @login_manager.user_loader def user_loader ( user_id ): """Given *user_id*, return the associated User object. :param unicode user_id: user_id (email) user to retrieve """ return User . query . get ( user_id ) @bull.route ( "/login" , methods = [ "GET" , "POST" ]) def login (): """For GET requests, display the login form. For POSTS, login the current user by processing the form.""" form = LoginForm () if form . validate_on_submit (): user = User . query . get ( form . email . data ) if user and bcrypt . check_password_hash ( user . password , form . password . data ): user . authenticated = True db . session . add ( user ) db . session . commit () login_user ( user , remember = True ) return redirect ( url_for ( "bull.reports" )) return render_template ( "login.html" , form = form ) @bull.route ( "/logout" , methods = [ "GET" ]) @login_required def logout (): """Logout the current user.""" user = current_user user . authenticated = False db . session . add ( user ) db . session . commit () logout_user () return render_template ( "logout.html" ) @bull.route ( '/<purchase_uuid>' ) def download_file ( purchase_uuid ): """Serve the file associated with the purchase whose ID is *purchase_uuid*. :param str purchase_uuid: Primary key of the purchase whose file we need to serve """ purchase = Purchase . query . get ( purchase_uuid ) if purchase : purchase . downloads_left -= 1 if purchase . downloads_left <= 0 : return render_template ( 'downloads_exceeded.html' ) db . session . commit () return send_from_directory ( directory = current_app . config [ 'FILE_DIRECTORY' ], filename = purchase . product . file_name , as_attachment = True ) else : abort ( 404 ) @bull.route ( '/buy' , methods = [ 'POST' ]) def buy (): """Facilitate the purchase of a product.""" stripe_token = request . form [ 'stripeToken' ] email = request . form [ 'stripeEmail' ] product_id = request . form [ 'product_id' ] product = Product . query . get ( product_id ) amount = int ( product . price * 100 ) try : charge = stripe . Charge . create ( amount = amount , currency = 'usd' , card = stripe_token , description = email ) except stripe . CardError : return render_template ( 'charge_error.html' ) current_app . logger . info ( charge ) purchase = Purchase ( uuid = str ( uuid . uuid4 ()), email = email , product = product ) db . session . add ( purchase ) db . session . commit () mail_html = render_template ( 'email.html' , url = purchase . uuid , ) message = Message ( html = mail_html , subject = current_app . config [ 'MAIL_SUBJECT' ], sender = current_app . config [ 'MAIL_FROM' ], recipients = [ email ]) with mail . connect () as conn : conn . send ( message ) return render_template ( 'success.html' , url = str ( purchase . uuid ), purchase = purchase , product = product , amount = amount ) @bull.route ( '/reports' ) @login_required def reports (): """Run and display various analytics reports.""" products = Product . query . all () purchases = Purchase . query . all () purchases_by_day = defaultdict ( lambda : { 'units' : 0 , 'sales' : 0.0 }) for purchase in purchases : purchase_date = purchase . sold_at . date () . strftime ( '%m- %d ' ) purchases_by_day [ purchase_date ][ 'units' ] += 1 purchases_by_day [ purchase_date ][ 'sales' ] += purchase . product . price purchase_days = sorted ( purchases_by_day . keys ()) units = len ( purchases ) total_sales = sum ([ p . product . price for p in purchases ]) return render_template ( 'reports.html' , products = products , purchase_days = purchase_days , purchases = purchases , purchases_by_day = purchases_by_day , units = units , total_sales = total_sales ) @bull.route ( '/test/<product_id>' ) def test ( product_id ): """Return a test page for live testing the "purchase" button. :param int product_id: id (primary key) of product to test. """ test_product = Product . query . get ( product_id ) return render_template ( 'test.html' , test_product = test_product )

Helpfully, Flask-login gives you access to the current user as current_user , allowing easy manipulation of the user's login status. The user_loader function is again required by Flask-login as a way to find a user based on their ID. In our case, that's a simple operation.

For the lone form required (the login form) I used the excellent Flask-WTF (a wrapper around WTForms). It gives you a programmatic interface to forms, much the same as Django provides. Our form is trivial, but more complex form-based work-flows are possible.

"I don't test often, but when I do, I test in production"

The above quote (which I stole from a T-Shirt I saw a co-worker wearing) was bull 's previous testing strategy. No more. Flask goes out of it's way to make testing easy, so we may as well make use of it. The primary way that we test an application in Flask is to import the Flask app instance and use the included test_client . The test_client allows us to make HTTP requests against our application easily, as shown in the file below. The following is taken from the file test_bull.py that lives in a tests directory at the top level of our project:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 """Tests for the Bull digital goods sales application.""" import datetime import unittest import uuid import os from flask import current_app from flask.ext.login import LoginManager , login_required , login_user from bull import app , mail , bcrypt from bull.models import db , User , Product , Purchase class BullTestCase ( unittest . TestCase ): """Main test cases for Bull.""" def setUp ( self ): """Pre-test activities.""" app . testing = True app . config [ 'STRIPE_SECRET_KEY' ] = 'foo' app . config [ 'STRIPE_PUBLIC_KEY' ] = 'bar' app . config [ 'SITE_NAME' ] = 'www.foo.com' app . config [ 'STRIPE_SECRET_KEY' ] = 'foo' app . config [ 'SQLALCHEMY_DATABASE_URI' ] = 'sqlite:///:memory:' app . config [ 'WTF_CSRF_ENABLED' ] = False app . config [ 'FILE_DIRECTORY' ] = os . path . abspath ( os . path . join ( os . path . split ( os . path . abspath ( __file__ ))[ 0 ], 'files' )) with app . app_context (): db . init_app ( current_app ) db . metadata . create_all ( db . engine ) mail . init_app ( current_app ) bcrypt . init_app ( current_app ) self . db = db self . app = app . test_client () self . purchase_uuid = str ( uuid . uuid4 ()) product = Product ( name = 'Test Product' , file_name = 'test.txt' , price = 5.01 ) purchase = Purchase ( product = product , email = 'foo@bar.com' , uuid = self . purchase_uuid , sold_at = datetime . datetime ( 2014 , 1 , 1 , 12 , 12 , 12 )) user = User ( email = 'admin@foo.com' , password = bcrypt . generate_password_hash ( 'password' )) db . session . add ( product ) db . session . add ( purchase ) db . session . add ( user ) db . session . commit () def test_get_test ( self ): """Does hitting the /test endpoint return the proper HTTP code?""" response = self . app . get ( '/test/1' ) assert response . status_code == 200 assert app . config [ 'STRIPE_PUBLIC_KEY' ] in response . data def test_get_user ( self ): """Can we retrieve the User instance created in setUp?""" with app . app_context (): user = User . query . get ( 'admin@foo.com' ) assert bcrypt . check_password_hash ( user . password , 'password' ) def test_get_product ( self ): """Can we retrieve the Product instance created in setUp?""" with app . app_context (): product = Product . query . get ( 1 ) assert product is not None assert product . name == 'Test Product' def test_get_purchase ( self ): """Can we retrieve the Purchase instance created in setUp?""" with app . app_context (): purchase = Purchase . query . get ( self . purchase_uuid ) assert purchase is not None assert purchase . product . price == 5.01 assert purchase . email == 'foo@bar.com' def test_download_file ( self ): """Given an existing purchase, does visiting the purchase's url allow us to download the file?.""" purchase_url = '/' + self . purchase_uuid response = self . app . get ( purchase_url ) assert response . data == 'Test content

' assert response . status_code == 200 def test_product_no_version_as_string ( self ): """Is the string representation of the Product model what we expect?""" with app . app_context (): product = Product . query . get ( 1 ) assert str ( product ) == 'Test Product' def test_product_with_version_as_string ( self ): """Is the string representation of the Product model what we expect?""" with app . app_context (): product = Product . query . get ( 1 ) product . version = '1.0' assert str ( product ) == 'Test Product (v1.0)' def test_get_purchase_date ( self ): """Can we retrieve the date of the Purchase instance created in setUp?""" with app . app_context (): purchase = Purchase . query . get ( self . purchase_uuid ) assert purchase . sell_date () == datetime . datetime ( 2014 , 1 , 1 ) . date () def test_get_purchase_string ( self ): """Is the string representation of the Purchase model what we expect?""" with app . app_context (): purchase = Purchase . query . get ( self . purchase_uuid ) assert str ( purchase ) == 'Test Product bought by foo@bar.com' def login ( self , username , password ): """Login user.""" return self . app . post ( '/login' , data = { 'email' : username , 'password' : password }, follow_redirects = True ) def test_user_authentication ( self ): """Do the authentication methods for the User model work as expected?""" with app . app_context (): user = User . query . get ( 'admin@foo.com' ) response = self . app . get ( '/reports' ) assert response . status_code == 401 assert self . login ( user . email , 'password' ) . status_code == 200 response = self . app . get ( '/reports' ) assert response . status_code == 200 assert 'drawSalesChart' in response . data response = self . app . get ( '/logout' ) assert response . status_code == 200 response = self . app . get ( '/reports' ) assert response . status_code == 401

The tests are short but rather exhaustive. We set up the test to use an in-memory SQLite database and add a Product , Purchase , and User object. The tests cover the major functionality of the application, with the most complex being the authentication test (though even that test is simple compared to the tests of other applications). Notice that most test cases check both the status_code and the data . Checking one or the other usually is not sufficient. Notice that, in the login method, we're even able to instruct the test_client to follow redirects to emulate our login flow. Testing Flask applications is well covered in the official Flask documentation, so head there if any of this is confusing.

You may notice I'm using assert statements rather than the unittest module's assertTrue and friends. That's because I exercise my tests using py.test rather than the unittest test-runner. I much prefer the former, but I usually write my tests in a way that is as compatible with unittest as possible in case I decide later to switch to another testing framework. One last thing to note is the docstrings in my test methods. I've lately been writing test docstrings in the form of a question. I've found that when a test fails, having the docstring represent the question we're trying to answer makes understanding what the purpose of an individual test is much more clear.

Sphinx on steroids

You're probably familiar with Sphinx and its apidoc capabilities. By running sphinx-apidoc , Sphinx generates the appropriate rst files with automodule directives, essentially generating all of the documentation for you project automatically (without you needing to hand-write rst files). Planning to use this in advance is crucial, as it means you'll be formatting your docstrings in a way that Sphinx recognizes.

What you may not be aware of is the existence of a third-party package, sphinxcontrib-httpdomain , that automatically documents your HTTP endpoints. This is a huge win, since for Flask applications, documentation on the functions that implement the endpoints is usually not what the user is looking for. Rather, they want to see how to use the endpoints themselves. By adding sphinxcontrib-httpdomain to your conf.py file and adding the following directive, you'll get exactly that:

1 2 .. autoflask :: bull:app :undoc-static:

This adds nice looking, JSON parameter-aware documentation generation to your project and is something your users will love you for using.

Automate all the things

As outlined in my article Open Sourcing a Python Project the Right Way, I set up TravisCI and coveralls.io integration with bull , as well as git-flow for the branching model. I also added a script, located at scripts/bull , that is installed along with the package and supports a single command, setup . Running bull setup creates the requisite app.py and config.py files as well as the files directory. Previously, the user would have to do this manually, going into their site-packages folder and copying the included versions into a new workspace. That was a silly and error-prone work-flow, so automating it makes sense. The last piece of the puzzle is the create_user.py script that populates the database with a single User object. The code for that file is as follows:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 #!/usr/bin/env python """Create a new admin user able to view the /reports endpoint.""" from getpass import getpass import sys from flask import current_app from bull import app , Product , Purchase , bcrypt from bull.models import User , db def main (): """Main entry point for script.""" with app . app_context (): db . metadata . create_all ( db . engine ) if User . query . all (): print 'A user already exists! Create another? (y/n):' , create = raw_input () if create == 'n' : return print 'Enter email address: ' , email = raw_input () password = getpass () assert password == getpass ( 'Password (again):' ) user = User ( email = email , password = bcrypt . generate_password_hash ( password )) db . session . add ( user ) db . session . commit () print 'User added.' if __name__ == '__main__' : sys . exit ( main ())

It's straightforward and does only what it needs to create a new user. Since it only needs to be run once per installation, I'm not too worried about adding bells and whistles.

One other nice piece of automation is a script I wrote for sandman: update_version.sh . It automatically does the following:

starts a release in git-flow updates the __version__ string in the package's __init__.py file deletes and re-generates the documentation commits the __init__.py change finishes the git-flow release uploads the new package to PyPI uploads the new documentation to pythonhosted.org

For those interested, here are the contents of the script, though you can probably guess them from the list above:

1 2 3 4 5 6 7 8 9 git flow release start v $1 sed -i -e "s/__version__ = '.*'/__version__ = ' $1 '/g" bull/__init__.py rm -rf docs/generated python setup.py develop make docs git commit docs bull/__init__.py -m "Update to version v $1 " git flow release finish v $1 python setup.py sdist upload -r pypi python setup.py upload_docs -r pypi

Wrapping up

So that's about it. From the mess of an application that the original bull release was, I've gotten bull to a place I'm happy with. The work-flow is all automated and includes sufficient testing and documentation. Using bull is simply a matter of pip install ing it, running bull setup , adding your configuration values, then configuring your web server to run it. That's all that's required to have a self-hosted digital goods payment solution with integrated analytics, and I'm pretty happy about that.