Python development environment Setup (OSX only)

-install homebrew

$ ruby -e "$(curl -fsSL https-//raw.github.com/Homebrew/homebrew/go/install)"

-install python 2.7 and pip 2.7 with homebrew

$ brew install python

-install virtualenv with pip

$ pip install virtualenv

New Flask project setup (OSX and Linux)

-create the project directory

$ mkdir [projectname]

-move to project directory

$ cd [projectname]

-create virtual environment and venv subfolder - one time per project operation

$ virtualenv -p $(which python) venv

-activate (or re-activate) the virtual environment

$ . venv/bin/activate

-install the flask package - specifying the version is optional

(venv)$ pip install Flask==0.10.1

-create (or re-create) requirements.txt with installed packages.

(venv)$ pip freeze > requirements.txt

-create application

(venv)$ touch app.py

-run the appication

(venv)$ python app.py

-de-activate the virtual environment

(venv)$ deactivate

Cloned Flask Project Setup (OSX and Linux)

-clone project from Github

$ git clone [projectURL]

-move to project directory

$ cd [projectname]

-create virtual environment and venv subfolder - one time per project operation

$ virtualenv -p $(which python) venv

-activate (or re-activate) the virtual environment

$ . venv/bin/activate

-install (or re-install) python packages listed in requirements.txt file

(venv)$ pip install -r requirements.txt

-run the appication

(venv)$ python app.py

-deactivate the virtual environment

(venv)$ deactivate

Running the application using manage.py

-In some projects the code for running the application is moved to a separate manage.py file in the root directory of the project

-run the application

(venv)$ python manage.py

Using autoenv to automatically activate the virtual environment

and export environment variables

-install autoenv with pip

$ pip install autoenv

-configure autoenv

$ echo 'source /usr/local/bin/activate.sh' >> ~/.bash_profile

-add a .env file to project root

-add ". venv/bin/activate" without the quotes to the .env file

-add "export DEBUG=True" without the quotes to the .env file

-Now whenever you cd into the project directory the .env file is executed automatically activating the virtual envoronment and exporting any exported variables

Serving using production servers

-run the application locally using gunicorn

The general form of the command for running with gunicorn is:

gunicorn -b 127.0.0.1:4000 [flask application instance container]:[flask application instance name]

where [flask application instance container] is a file or directory inside the project root. If it is a file then it is the name of the file in which the app instance is created or the name of the file that imports the app instance. If it is a directory then it is the name of a python package directory where the app instance resides inside the [init.py] file

Example where the flask application instance named app is imported in a manage.py file.

(venv)$ gunicorn -b 127.0.0.1:4000 manage:app

Example where the flask application instance named app is created inside the app.py file or is created in the init.py file inside a directory named app.

(venv)$ gunicorn -b 127.0.0.1:4000 app:app

-run the application on Heroku using gunicorn

in Procfile add:

web: gunicorn manage:app

or

web: gunicorn app:app

Flask resources

the flask website http://flask.pocoo.org/

an online reference book that also coveres organising large flask apps with blueprints https://exploreflask.com/

the best step by step online tutorials for flask https://realpython.com/blog/

the realpython youtube channel: https://www.youtube.com/playlist?list=PLLjmbh6XPGK5e0IbpMccp7NmJHnN8O1ng

a compilation of flask resources http://www.fullstackpython.com/flask.html

The definitive flask book from oreilly http://flaskbook.com/

exellent blog from the author of the orielly flask book http://blog.miguelgrinberg.com/

this sets up a basic flask app including self hosting server configuration http://maximebf.com/blog/2012/10/building-websites-in-python-with-flask/#.VKxL7mTZln4

this covers the use of blueprints http://maximebf.com/blog/2012/11/getting-bigger-with-flask/#.VKxL0WTZln4

excellent intro to flask. Requires a subscription but has free trial period. http://www.pluralsight.com/courses/flask-micro-framework-introduction

flask approved extension list http://flask.pocoo.org/extensions/

Common Flask extensions

for running tasks from command line: http://flask-script.readthedocs.org/en/latest/

for html form handling and validation: https://flask-wtf.readthedocs.org/en/latest/

for data models and ORM: https://pythonhosted.org/Flask-SQLAlchemy/

for database schema migrations: https://flask-migrate.readthedocs.org/en/latest/

for user authentication: https://flask-login.readthedocs.org/en/latest/

for testing: https://pythonhosted.org/Flask-Testing/