Setup Instructions

This code sample demonstrates how setup a simple Flask application using application virtualization.

1) Install Python and a code editor.

Follow the directions for your operating system here https://www.python.org/

Personally I recommend Visual Studio Code as a editor but there are also many others. https://code.visualstudio.com/

2) Create a project directory.

mkdir MyWebApp (Mac/Linux) or md MyWebApp (Windows) cd MyWebApp

3) Create the virtual engironment.

pip3 install pipenv This will install the virtual environment package on your computer. pipenv install This will create a virtual environment. pipenv shell This will start the virtual environment. exit This will close (exit) the virtual environment. pipenv shell You can run this any time to restart the virtual environment.

If you get an error. It could be because you have multiple version of Python installed. If this applies to you try add "python3 -m" to the commands.

`python3 -m  pip3 install pipenv
python3 -m  pipenv install
python3 -m pipenv shell 

4) Install Flask

This will install the flask package to the virtual environment. pipenv install flask
Test the flask command to see if it installed properly.
flask

4) Build the application.

Create the app.py file and in this example the templates\hello.html file.

5) Run the application.

Use flask run at the command prompt to launch the application.

6) Enable debug mode and troubleshooting.

Flask uses a couple of command line environmental variables. The FLASK_APP variable sets the name of the python script to run. and FLASK_ENV can be used to put Flask into development mode which will provide better debug messages and enable auto-reload when you make file changes. Which means you don't need to stop and start Flask every time you make a change.

For Linux and Mac users you can set the variables like this.

    export FLASK_APP=app.py
    export FLASK_ENV=development
    flask run

In Windows Powershell

$env:FLASK_APP = "app.py"
$env:FLASK_ENV = "development"
flask run