AI Deploy - Tutorial - Deploy a simple app with Flask

Last updated 31st January, 2023.

Objective

Flask is an open-source micro framework for web development in Python.

The purpose of this tutorial is to show you how to build and use a custom Docker image for a Flask application.

Requirements

• Access to the OVHcloud Control Panel;
• An AI Deploy project created inside a Public Cloud project in your OVHcloud account;
• A user for AI Deploy;
• Docker installed on your local computer;
• Some knowledge about building image and Dockerfile.

Instructions

Write a simple Flask application

Create a simple Python file with name app.py.

Inside that file, import your required modules:

from flask import Flask

Create Flask app:

app = Flask(__name__)

Define a simple function:

@app.route('/')
def index():
    return 'Web App with Python Flask using AI Deploy!'

Start your app:

if __name__ == '__main__':
    # starting app
    app.run(debug=True,host='0.0.0.0')

• More information about Flask can be found here.
• Direct link to the full python file can be found here here.

Write the requirements.txt for your applications

The requirements.txt file will allow us to write all the modules needed to make our application work. This file will be useful when writing the Dockerfile.

Flask==1.1.2

Write the Dockerfile for your application

Your Dockerfile should start with the the FROM instruction indicating the parent image to use. In our case we choose to start from a classic Python image.

FROM python

Install the requirements.txt file which contains your needed Python modules using a pip install ... command:

RUN pip install -r requirements.txt

Define your default launching command to start the application.

CMD [ "python" , "/workspace/app.py" ]

Give correct access rights to ovhcloud user (42420:42420):

RUN chown -R 42420:42420 /workspace
ENV HOME=/workspace

• More information about Dockerfiles can be found here.
• Direct link to the full Dockerfile can be found here here.

Build the Docker image from the Dockerfile

Launch the following command from the Dockerfile directory to build your application image:

docker build . -t flask-app:latest

Test it locally (optional)

Launch the following docker command to launch your application locally on your computer:

docker run --rm -it -p 5000:5000 --user=42420:42420 flask-app:latest

Once started, your application should be available on http://localhost:5000.

Push the image into the shared registry

Find the address of your shared registry by launching this command:

ovhai registry list

Log in on the shared registry with your usual OpenStack credentials:

docker login -u <user> -p <password> <shared-registry-address>

Push the compiled image into the shared registry:

docker tag flask-app:latest <shared-registry-address>/flask-app:latest
docker push <shared-registry-address>/flask-app:latest

Launch the AI Deploy app

The following command starts a new app running your Flask application:

ovhai app run --default-http-port 5000 --cpu 1 <shared-registry-address>/flask-app:latest

Once the app is running you can access your Flask application directly from the app's URL.

Go further

• To go further with Flask, imagine creating an app to deploy an Object Detection model. Refer to this tutorial.
• Flask allows you to do sentiment classification on texts using Hugging Face models. Here it is.

Feedback

Please send us your questions, feedback and suggestions to improve the service:

• On the OVHcloud Discord server

Potrebbero interessarti anche...