Today we're going to look at how to deploy applications to the web so that others can view them. The goal here is not to create a production-ready system. While we'll incorporate some libraries that are highly performant, we won't be following the absolute best practices for industry use so that we can instead make things a bit easier to prototype.
Requirements: Python 3 | Flask | WhiteNoise | free Render account | GitHub account (recommended) (you can use pip to install "flask" and "whitenoise")
A number of cloud "platform as a service" tools exist for hosting web-based projects efficiently. In short, they allow you to upload web server code to a cloud backend which then does the hard part of making them web-accessible. While today we will make use of Render, there are many different providers. These include (in no particular order) Microsoft Azure, AWS, Railway, Fly.io, and Digital Ocean among many others. I encourage you to examine each and figure out which set of features and end-user agreement works best for you. For the purposes of this class, you should not need a paid account.
Important note: You may not need a full Render web service to host a basic homework project. While I am demoing a full web service today, check out Render's ability to serve static sites which will likely suffice for HW1, HW2, etc.
Our system will involve the following components:
At the conclusion of the class, you'll be able to find the files we used here. You can access the Render site we created here.
Commands used in the lecture:
# Go on GitHub and make a new project for your code
# (you can also add collaborators at this time)
# Clone your repository on your computer
git clone -REPOSITORY URL-
# Render needs a requirements file
# Use a text editor of your choice. I use Atom, which can run from the command line
atom requirements.txt
# It includes:
# gunicorn - library that runs our code as a web service, must include
# flask - imported in our .py
# whitenoise - imported in our .py
# Verify that you have installed all of the libraries you are requiring
pip install -r requirements.txt
# Make a Flask app (make sure Python 3, Flask, and WhiteNoise are installed)
atom app.py
# See the demo files for what we added to app.py
# At this point we also made a static directory and put some files in it for Whitenoise to serve
# Test Flask server to see if it works (command may just be python for your machine)
python app.py
# Commit the changes to your local git repository
git status
git add app.py
git add requirements.txt
# etc. to add all changed/added files
# Now commit the changes and push to Github
git commit -m "first commit"
git push 
# You now need to set up a project on Render. If is easiest if you connect your account
# Pick Web Services from the list and select your repository
# Render usually figures out what kind of service you need, but it may get settings wrong
# Make sure you have set:
# Python or Python 3.7 for Environment
# pip install -r requirements.txt in Build Command
# gunicorn app:app in Start Command
# Once you create your page, it will begin to build. Check the page for errors/logs
# If you want to modify your page, commit the changes to your repository
# Then just use the Render menu to pull from your latest commit to update and rebuild