Dockerize Simple Python App

Introduction :

In this blog, we will concentrate on writing Dockerfile to dockerize the simple hello world python flask app.

Prerequisite:

Docker
Linux Machine
Python 2.7 or above.

Step 1 | Creating Dockerfile for your app.

Application Folder Structure

Web

  ____ app.py
  ____ requirements.txt
  ____ Dockerfile

app.py

from flask import Flask
app = Flask(__name__)

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

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

requirements.txt

Flask==0.12

Dockerfile:

Dockerfile consists set of instructions which are used to create docker image of the application. A Dockerfile
contains all those commands that require starting the app.
We will build image with the latest version of ubuntu,

# Format: FROM    repository[:version]
FROM       ubuntu:latest

Copy the app in our remote container,

COPY . /app
WORKDIR /app

We will begin with the installing necessary dependencies to run the app,

RUN apt-get update -y
RUN apt-get install -y python-pip python-dev build-essential
RUN pip install -r requirements.txt

We will set the Entrypoint
which will tell docker to run python
inside the docker container.

ENTRYPOINT ["python"]

To run the app we will add command ,

CMD ["app.py"]

So finally we will get Dockerfile as ,

# Format: FROM    repository[:version]
FROM       ubuntu:latest
RUN apt-get update -y
RUN apt-get install -y python-pip python-dev build-essential
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
ENTRYPOINT ["python"]
CMD ["app.py"]

Step 2 | Build the docker image

Run the following command to create the docker image from web
directory,

$ docker build -t helloworldapp:latest .

Step 3 | Run the docker container

Run the docker container from a created image,

$ docker run -d -p 5000:5000 helloworldapp

You can access the app using hostname:5000 port. If you are running this on locally then you can access it by localhost:5000

You can check the running containers with docker ps command,

docker ps 
CONTAINER ID        IMAGE               COMMAND            
fb5ce111110d        helloworldapp       "python app.py" ...

Dockerize Simple Python App

Jakir Patel

Docker python