Deploy flask application on Azure app service using your own domain

In this post I want to describe the 3 steps to make your flask app (hello world) and have it deployed on Azure and accessible via your own domain / website. Although it is a static hello world application that will be created, I think it is interesting as in a later stage this can be applied on machine learning or natural language processing apps. They will typically require an app engine.

Create a hello world app with Flask, locally

Of course, everything starts with having your Python and Flask installation right. The flask tutorial installation guide is clear and easy to do.

It is good to have discipline in respecting some ground rules: installing Flask in a virtual environment, work with a seperate project folder each time and upgrading to the required Python version. These best practices save some time and frustration afterwards. For Python I work with an Anaconda distribution.

Creating a hello world app following the flask tutorial, is again an easy game.

First hello world can be copy-pasted from above mentioned tutorial. Try to understand what it means.

Deploy it to Azure as an application

So you have a hello world running on localhost but want to make it publically accessible? On the flask website you will see a list of options for (cloud) deployment.

I chose for Azure for this post. Main reason is the ease of deployment. Azure offers an out of the box container with the recommended Python version for flask pre-installed (being 3.7 at the time of writing). Steps to be taken can be found here.

You should of course have an Azure login. You will be prompted to choose for an Azure cloud shell. In case you don't have a storage account yet, you will be required to create it here. There is a free trial for 12 months. The steps to do so are self-explanatory. The shell will startup once storage account is created.

Confirmation that the storage account is created

From here you need to create your deployment user, user group and app service plan. Simple copy pasting the code in above-mentioned tutorail in the Azure shell is sufficient.

Setup of a local git directory is required (so NOT in the azure shell but in your local cmd):

cd "localdirpath"

git --bare init (in case you are not storing the repository on github)

git add .

git commit -m 'message'

The app is now deployed and has a unique endpoint containing the name of your app you chose in the steps above.

Azure link in adress bar, body showing hello world

Link the app to your own domain

The minimal monthly cost of above Azure deployment is 32€ per month (European region). You will get by default one month free trial. Anyhow if you want to deploy to your own domainname - which I want towards www.nlpit.be/hello - you need a paying app service plan. The free tier is not supported. Again a clear tutorial will guide you through. You will need to link the unique app endpoint in the DNS configuration portal of the domain provider.

Printscreen of the DNS line in the portal of my provider

Whilst adding the domainname in Azure. The tutorial warns for a domain ownership issue as in the printscreen (right below - red exclamation mark). This can be due to a typo. On the other hand, DNS propagation takes a while. So if it doesn’t work immediately, don’t panic. Wait for some hours and try again to add the hostname.

Printscreen of Azure whilst adding the hostname

For me the propagation was done after 15 minutes.

Printscreen of domain in adress bar and hello world in body

The app is now deployed and coupled to your own domain name / website.