Can't run client-server application with docker

Question

Good day! I wrote client and server applications, I run them via docker, but client app couldn't connect to server.

Client's code:

import requests
import json

class Client:
    def attach_comp_to_employee(self, employee_id, company):
        try:
            res = requests.get('http://0.0.0.0:8080/',
                               data=json.dumps({"action": "comp_to_employee",
                                                "id": employee_id,
                                                "company": company,
                                                "owner_name": self.user,
                                                "dbname": self.dbname,
                                                "password": self.password}),
                               timeout=3)
        except requests.exceptions.ConnectionError:
            res = "Can't connect to server."
        except requests.exceptions.Timeout:
            res = "Time for connection expired."
        finally:
            return res

cl = Client("test_user1", "shop", "password1")
print("Send...")
res = cl.attach_comp_to_employee(6, "ABCD")
print(res)

Server's code:

from aiohttp import web

class Service:
    def __init__(self):
        self.app = web.Application()
        self.app.add_routes([web.get('/', self.handler)])

    async def handler(self, request):
        return web.json_response({"response": "Hi"})

print("Start...")
ser = Service()
web.run_app(ser.app)

I created two dockerfiles for them.

Dockerfile for client:

FROM python:3
WORKDIR /app
ADD . /app
RUN pip3 install requests
CMD ["python3", "client.py"]

Dockerfile for server:

FROM python:3
WORKDIR /app
ADD . /app
RUN pip3 install aiohttp
CMD ["python3", "server.py"]

Then I created docker-compose.yml:

version: '3'
services:
  server:
    build: ./server
  client:
    build: ./client
    links:
      - "server:localhost"

After all my directory looks like:

project
|___server
|      |__Dockerfile
|      |__server.py
|__client
|      |__Dockerfile
|      |__client.py
|__docker_compose.yml

When I run docker-compose up I see this:

docker-compose up

If I interrupt it with Cntr+ C I will see this:

interrupt

So the server is running and is waiting for requests.

Help me please. What is wrong in my code? What should I do to connect this two scripts?

Answer 1

your backend container is the server - therefore it needs to listen on specific ports to accept the client requests.

expose ports in your Dockerfile:

FROM python:3
WORKDIR /app
ADD . /app
RUN pip3 install aiohttp
EXPOSE 8080
CMD ["python3", "server.py"]

now, as a side note, as @Klaus D. commented out, -the docker-compose links option shouldn't be in use any more. instead, in your code, refer directly to the server container name.

good luck!