Docker Compose port mapping: 127.0.0.1 refused to connect - docker

Question

I am currently working with Docker and a simple Flask website to which I want to send images. For this I'm working on port 8080, but the mapping from docker to host is not working properly as I am unable to connect. Could someone explain to me what I am doing wrong?
docker-compose.yml
version: "2.3"
services:
dev:
container_name: xvision-dev
build:
context: ./
dockerfile: docker/dev.dockerfile
working_dir: /app
volumes:
- .:/app
- /path/to/images:/app/images
ports:
- "127.0.0.1:8080:8080"
- "8080"
- "8080:8080"
dev.dockerfile
FROM tensorflow/tensorflow:latest
WORKDIR /app
COPY requirements.txt ./
RUN pip install -r requirements.txt
RUN apt update && apt install -y python-tk
EXPOSE 8080
CMD ["python", "-u", "app.py"]
app.py
#APP.route('/test', methods=['GET'])
def hello():
return "Hello world!"
def main():
"""Start the script"""
APP.json_encoder = Float32Encoder
APP.run(host="127.0.0.1", port=os.getenv('PORT', 8080))
I start my docker with docker-compose up, this gives the output: Running on http://127.0.0.1:8080/ (Press CTRL+C to quit).
But when I do a get request to 127.0.0.1:8080/test I get that there is no response.
I have also tried docker-compose run --service-port dev as some people have suggested online but this says that there is no service dev.
Can someone help me for what I am doing wrong?

Answer 1

Use:
APP.run(host="0.0.0.0", port=os.getenv('PORT', 8080))
Using only:
ports:
- "8080:8080"
is enough