Flask-Python3-Starter-Kit

by © djengineer 2022

Date updated: 18 OCTOBER 2022

Purpose:

This starter kit includes a starting bootstrap jumbotron template using bootstrap-4.0.0, python3.9 in the virtual environment. You can check the items installed in the requirements.txt.

This is a basic template to jumpstart lightweight python webapps using the base Flask, or Flask-RESTful if you are creating an api backend.

This doc includes:

• pip packages
• other files
• venv details
• Setting up system environment in linux OSes
• How to start the local server

How connect to the applications

flask_app.py

This is for the normal flask application.

http://localhost:8080
http://localhost:8080/form
http://localhost:8080/page1

flask_restful_app.py

This is a RESTFUL flask API application

http://localhost:8081/example/url/hey%20there

Getting Started (Linux)

Set up the environment

Install python and python virtual environment packages. You may install the packages for the latest python instead.

sudo apt install python3.9 python3.9-venv -y

Create a new venv folder. This will create a new folder called "venv" with the virtual environment.

# the terminal should be in the python project folder.
python3.9 -m venv venv

Have the terminal use the virtual environment

source ./venv/bin/activate

You should see a (venv) in the terminal.

Starting the servers

Using the new (venv) environment, go to the project folder. We will install the dependencies.

# install the required packages if it is the first time starting up.
pip install -r requirements.txt

To start the servers, use the following commands.

# to start flask
python flask_app.py

# to start flask
python flask_restful_app.py

Deploying

When deploying a flask app, the main script should be called flask_app.py. If you are running two servers, then split the two into separate project folders.

pip packages include:

• Pandas
• Numpy
• flask
• flask-restful
• flask-mongoengine
• flask-mqtt

Package explanations

• https://www.w3schools.com/python/python_mongodb_getstarted.asp: PyMongo is needed for MongoDB non-relational database.
• https://flask.palletsprojects.com/en/2.2.x/patterns/mongoengine/ : MongoEngine is needed to connect with the MongoDB.
• https://mqtt.org/ : MQTT is an IoT messaging standard
• https://www.redhat.com/en/topics/api/what-is-a-rest-api: REST/RESTFUL is a api standard definition. Uses HTTP for req and response.

Others files:

• Bootstrap 4.0.0-dist
• Proc file
• requirements.txt

Venv:

Python 3.9 as per the apt-get python3.9 below

Setting up the system environment to run the virtual environment

If you have python3.9 in your system already, you may skip this part. However, you may need to install python3.9-venv before you can use the venv that is included in this kit.

For users with using linux os, use the bash script to install python3.6 and python3.6-venv

Use the following command to activate the venv

source venv/bin/activate

For windows or other OSes, make sure you have python3.9

You may want to consider using Anaconda to manage virtual environments in windows.

https://www.anaconda.com/

To run the flask server

If you have a local terminal:

python flask_app.py

If you want to run the flask-restful, it is best-practice to change the file name to flask_app.py

Different hosts have different way of starting the app. Please refer to their respective docs for more information.

Upgrading dependencies(requirements.txt) in the future

https://stackoverflow.com/questions/24764549/upgrade-python-packages-from-requirements-txt-using-pip-command

pip install pip-upgrader
pip-upgrade ./requirements.txt