Connecting selenium grid to flask app error

app.py

from flask import Flask

app = Flask(__name__)


@app.route('/')
def hi():
    return 'hello'

conftest.py

import pytest
from app import app as a

@pytest.fixture
def app():
    app = a
    return app

docker-compose.yml

version: "3"

services:
  app:
    build:
      context: .
      dockerfile: deploy/app/Dockerfile
    depends_on:
      - selenium-hub
    environment:
      - FLASK_APP=api.py
      - FLASK_ENV=development
    volumes:
      - ./src:/src
      - ./tests:/tests
    ports:
      - "5000:5000"
    stdin_open: true
    command: bash -c "flask run --host 0.0.0.0"

  selenium-hub:
    image: selenium/hub:latest
    ports:
      - "4444:4444"

  selenium-chrome:
    image: selenium/node-chrome-debug
    stdin_open: true
    links:
      - selenium-hub
    environment:
      - HUB_HOST=selenium-hub

Dockerfile

FROM python:3.8-buster

COPY ./requirements.txt /tmp/

RUN pip install --upgrade pip

RUN pip install -r /tmp/requirements.txt

RUN mkdir -p /src
COPY /src /src
RUN pip install -e /src
RUN mkdir -p /tests
COPY /tests /tests

WORKDIR /src

requirements.txt

flask

# Testing
pytest
pytest-selenium
pytest-flask

test_end_to_end.py

import pytest

@pytest.fixture
def selenium(selenium, live_server):
    yield selenium
    selenium.close()

def test_opening_up_web_page(selenium):

    # GIVEN the web page
    selenium.get(f'http://localhost:5000')
# ->print(selenium.page_source)  --> Error here