Docker Compose Network Interaction Example

app.py

import requests
from flask import Flask, request

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello from {}".format(request.host)

@app.route("/request/<int:port>")
def doPing(port):
    ret = None
    try:
        location = "http://localhost:{}/".format(port)
        ret = requests.get(location, timeout=5).content
    except Exception as e:
        ret = "Unable to retrieve: {}".format(e)
    return ret

docker-compose.yaml

version: '3'
services:
    receiver:
        build: ./app
        expose:
            - 3000
        ports:
            - 3000:3000
        command: "--host 0.0.0.0 --port 3000"
    requester:
        build: ./app
        expose:
            - 4000
        ports:
            - 4000:4000
        command: "--host 0.0.0.0 --port 4000"

Dockerfile

FROM python:3

COPY . /app

WORKDIR /app

RUN pip install -r requirements.txt

ENV FLASK_APP=/app/app.py

ENTRYPOINT ["flask", "run"]

requirements.txt

requests
flask