In this article, we will see how to create a Flask app, run the containerized Flask app using Docker and finally push the Docker images into DockerHub.

Create a Flask app

1. Create a Flask app directory

    mkdir flask-app
    cd flask-app
   

2. Create a Python virtual environment and activate it.

    python3 -m venv venv
    source venv/bin/activate
   

3. Install Flask app

    pip install flask
   

4. Create the requirements.txt file with the installed packages under the current environment.

    pip freeze > requirements.txt
   

5. Create the app.py file

    # Import flask module
    from flask import Flask
   
    app = Flask(__name__)
   
    @app.route('/')
    def index():
        return "<h1> This is a flask app containerized with Docker. </h1>"
   
    # main driver function
    if __name__ == "__main__":
       app.run()
   

6. The Flask app is ready. Now run using this script with Python

    flask run --host 0.0.0.0 --port 5000
   

Create a docker file for the Flask app

1. Create a Dockerfile under the project directory.

   vim Dockerfile

    FROM python:3.10-slim-buster
   
    MAINTAINER Anjali
   
    # Create app directory
    WORKDIR /flask-app
   
    # Bundle app source
    COPY . .
   
    # Install the required dependencies
    RUN pip install -r requirements.txt
   
    EXPOSE 5000
   
    CMD [ "flask", "run","--host","0.0.0.0","--port","5000"]
   

2. Create a docker image from this file. It will be created in the local image registry.

    docker build -t flask-app .
   

3. Run the docker container

    sudo docker run -d -p 5000:5000 --name flask-app flask-app
   

4. Now verify your container

    docker containers ls
   

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Push the docker image to Dockerhub

1. Login to docker hub with the username and password.

docker login

1. Tag the local docker image with the docker hub username

    docker tag flask-app:latest <your_dockerhub_username>/flask-docker-app-img:latest
   

2. Push the tagged image to docker hub

    docker push <your_dockerhub_username>/flask-docker-app-img:latest
   

We have seen how to create a simple flask app then create a docker image using Dockerfile and finally push the docker image to docker hub.

Keep Learning :)