Flask is a simplest and easy to use micro framework for web application development. It doesn’t require any special libraries to get started. You can create a basic application in a couple of minutes. Here we will create a basic flask web application.

Azure is a cloud platfrom by Microsoft for buliding, create, testing and deploying applications on cloud and has many other features such as databases and many more. It also has Azure App Service and VM services for application deployment. You can also use Kubernetes Engine for deploying application for a larger community. In our tutorial we will using Azure app service. So you need to enable billing on Azure to use azure app service. They also offer a one month trial to get started on account creation.

Docker is a set of platform as service products to help deploy application regardless of an operating system of given environment. We can deliver software using pakages called docker container. Docke container are isolated from one another and can communicate with each other. You can download and install docker for your operating system from docker hub. For this tutorial you need to create an account on Docker hub. https://www.docker.com/products/docker-desktop

Now after installing docker and creating account on Azure and docker hub. We get started with creating a basic flask application. For a flask application you need to install python on your operating system. And to use flask you can install it via command line.

pip install flask

Create a flask application

Open a text/code editor and write this code to create a basic flask application named “main.py”

from flask import Flask
app = Flask(__name__)


@app.route('/')
def hello():
    return "Hello World!"

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=80)

Now to run application on your system type “python main.py” by opening a terminal in current directory and navigate to http://localhost or http://0.0.0.0 to test your application.

Next we need to configure for docker with following configuration. Create a Dockerfile with no extension

FROM tiangolo/uwsgi-nginx-flask:python3.6

COPY ./requirements.txt .
RUN pip install -r requirements.txt

COPY ./app /app

Create another file requirments.txt in current folder and type flask in it. Now create a new folder in current directory named app and move main.py to it. Your file structure will look like follow.

.
|-app
	└─ main.py
|-Dockerfile
|-requirements.txt

Open terminal and type

docker build -t YOUR_DOCKERHUB_USERNAME/PROJECT_NAME .
# For example
docker build -t faizan170/test-app .

First it will download image and install libraries given in requirements.txt file. Then it will create a docker image. When process is complete, to check if application is working. Execute this command and navigate to http://localhost.

docker run -p 80:80 YOUR_REPO_NAME

Now if application is working, push image to docker hub using

docker push YOUR_REPO_NAME

Once you have pushed image to docker hub, navigate to Azure Portal for deployment. https://portal.azure.com. In app services section. Click on create a new app.

In application settings, follow these steps

• Create or select a resource group
• Write a unique name for your application
• In publish section select docker container
• Leave remaining step as default as move to select docker option

Now, in image source, select docker hub and type your docker image name in Image and tag section. Change other options as your requirements, if you want to otherwise click on Review + Create

Once validation is completed. Click on create to create your application. It will take, 2 to 3 minutes and your application will be live. Once this process is completed, navigate to your url to check if application is working.

You caan get complete code for this post from this github link.

https://github.com/ml-blog/flask-application-nginx-docker-demo