flask app containerized using docker

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

Create a Flask app directory
```
 mkdir flask-app
 cd flask-app
```

Create a Python virtual environment and activate it.

 python3 -m venv venv
 source venv/bin/activate

Install Flask app
```
 pip install flask
```
Create the requirements.txt file with the installed packages under the current environment.
```
 pip freeze > requirements.txt
```

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()

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

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"]

Create a docker image from this file. It will be created in the local image registry.
```
 docker build -t flask-app .
```

Run the docker container

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

Now verify your container
```
 docker containers ls
```

Push the docker image to Dockerhub

docker login

Tag the local docker image with the docker hub username

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

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 :)

Create and run a Flask app using Docker

Create a Flask app

Create a docker file for the Flask app

Push the docker image to Dockerhub