Timeout Mongodb with Docker

Question

I'm having trouble working my code in docker. Could you please help me?

I'm putting my application in docker together with mongo in docker, but when I run the file inside docker it doesn't connect with the mongo of the other docker and accuses Timeout.

My Docker:

version: "3.4"

services:

  mongo_db:
    image: mongo:6.0
    ports:
      - "27017:27017"
    volumes:
      - ./mongo_db:/data/db
    container_name: mongo_db

  mongo_app:
    image: mongo_img_db:latest
    links:
      - mongo_db
    command: python3 /app/main.py
    container_name: mongo_app

Error:

@@@ Connection: Database(MongoClient(host=['localhost:27017'], document_class=dict, tz_aware=False, connect=True), 'app')
Traceback (most recent call last):
  File "/app/main.py", line 216, in <module>
    db_calc.update_storage_stats(db_calc.calculate_artifacts_size())
  File "/app/main.py", line 43, in calculate_artifacts_size
    artifacts_size = self.db_client.builds.aggregate(
  File "/usr/local/lib/python3.9/site-packages/pymongo/collection.py", line 2428, in aggregate
    with self.__database.client._tmp_session(session, close=False) as s:
  File "/usr/local/lib/python3.9/contextlib.py", line 119, in __enter__
    return next(self.gen)
  File "/usr/local/lib/python3.9/site-packages/pymongo/mongo_client.py", line 1757, in _tmp_session
    s = self._ensure_session(session)
  File "/usr/local/lib/python3.9/site-packages/pymongo/mongo_client.py", line 1740, in _ensure_session
    return self.__start_session(True, causal_consistency=False)
  File "/usr/local/lib/python3.9/site-packages/pymongo/mongo_client.py", line 1685, in __start_session
    self._topology._check_implicit_session_support()
  File "/usr/local/lib/python3.9/site-packages/pymongo/topology.py", line 538, in _check_implicit_session_support
    self._check_session_support()
  File "/usr/local/lib/python3.9/site-packages/pymongo/topology.py", line 554, in _check_session_support
    self._select_servers_loop(
  File "/usr/local/lib/python3.9/site-packages/pymongo/topology.py", line 238, in _select_servers_loop
    raise ServerSelectionTimeoutError(
pymongo.errors.ServerSelectionTimeoutError: localhost:27017: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 63542415a868649d12f2a966, topology_type: Unknown, servers: [<ServerDescription ('localhost', 27017) server_type: Unknown, rtt: None, error=AutoReconnect('localhost:27017: [Errno 111] Connection refused')>]>