Tuesday, October 1, 2013

Setup: Python/Flask dev environment on windows using virtualenv and pip

Chacolateyis a sudo apt-get for the windows crowd and its awesome! Chacolatey makes it incredibly easy to setup multiple dev environments for Python/flask/django which is otherwise a multi-step process (installing setuptools, pip, virtualenv etc). Here are the steps.

Install Chacolatey

Launch a powershell prompt using "Run As Admin" and set execution policy to unrestricted.

Set-ExecutionPolicy Unrestricted

And run the following command in the same window to install chacolatey

iex ((new-object net.webclient).DownloadString('https://chocolatey.org/install.ps1'))

Once its installed, you'll have csint added to your path and it is the equivalent of apt-get.

Install Python

If you don't already have Python installed, run the following in a powershell/cmd

cinst Python

This will install Python 2.7 at C:\Python27. We need a few more things to setup a proper dev environment. Instead of installing flask package directly to the main Python installation, it can be separated using virtualenv. If you are developing an app on django and another using flask and would like to keep these environments separate, virtualenv is the way to go.

Install Pip

cinst pip

pip install virtualenvwrapper
pip install virtualenvwrapper-powershell

This will add virtualenv.exe to your system path and you can create multiple Python dev environments using this. Lets call our flask app FlaskApp. Lets create a directory for this app on D drive. Create a virtual env in that folder.

virtualenv FlaskApp

This will create a Python instance in FlaskApp folder. Now activate the virtual environment we just created. cd to FlaskApp/Scripts and run activate

cd FlaskApp\Scripts\
#your command line should change to (FlaskApp) D:\FlaskApp\Scripts. 
pip install flask
# To come out of (FlaskApp), simply type 'deactivate'

Now you are all set. We created a virtual environment called FlaskApp and installed flask package. Lets see if it works. Create a sample app. Create a hello.py with below

-- the above line is to let the computer run python.exe from our VirtualEnv not the system wide Python
from flask import Flask
app = Flask(__name__)

def hello_world():
    return 'Hello World!'

if __name__ == '__main__':


Python hello.py

It should run the web server on