Flask app not running in docker container

Question

I am learning docker using flask application.Here is the below code I am using

app.py

from flask import Flask



app = Flask(__name__)


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

if __name__ == "__main__":
    app.run(debug=True)

Dockerfile

FROM python:3

WORKDIR /app
COPY requirements.txt requirements.txt
RUN pip3 install -r requirements.txt

COPY . .

ENTRYPOINT ["python3", "app.py"]

docker-compose.yml

version: '3.9'
services:
  flask:
    build: .
    image: myapp:latest

When I tried to run the above flask app through python3 app.py it works on the port 5000 correctly.But when I tried to dockerize it docker compose up --build shows that the app is started no error or warning logs but localhost is not getting connected

[![localhost not connected][1]][1]

In Dockerfile I tried specifying the host also.Nothing worked. Can someone tell me how to resolve this issue?

I have tried all the solutions mentioned in this link Deploying a minimal flask app in docker - server connection issues

But still having the same issue. I have created a virtual env for this flask app and trying to run the docker container. After changing

app.run()

to

app.run(host='0.0.0.0')

and tried docker run <container_id> got the following console response

Kindly look all the attached image for clear reference

I could see that the app is running in my localhost as well as in some other ip.Attaching the below screenshot for the reference. Can some one address this issue? [1]: https://i.stack.imgur.com/1yboh.png

score 1 · Answer 1 · answered Mar 24 '23 at 06:41

1

Change docker-compose to this

version: '3.9'
services:
  flask:
    build: .
    image: myapp:latest
    ports:
     - "5000"

answered Mar 24 '23 at 06:41

Abhishek

423
6
12

I tried with the above changes.Still the same issue. Localhost is unknown – Sowmya Ravichandran Mar 24 '23 at 06:48
1

try `ports: - "5000:5000"` – Abhishek Mar 24 '23 at 06:53

score 1 · Answer 2 · answered Mar 24 '23 at 06:46

You need to map a port in docker. To do that, add a ports field to your docker-compose.yml file. For example:

version: '3.9'
services:
  flask:
    build: .
    image: myapp:latest
    ports:
      - "81:80"

The Flask server will listen on port 80. You can now access the application using port 81 on your machine. More detail

Flask app not running in docker container

2 Answers2