Mongodb error [pymongo.errors.ServerSelectionTimeoutError] in flask web-service-CodePudding

So i made a flask web-service that connects to a mongodb , the web-service will be in a docker container and the mongodb will be in another container. When i run the web-service locally on my computer it connects to the mongodb container and everything works fine. When i have them in 2 separated containers as described before, i can use GET methods just fine but POST methods never works, every time i try to make a change in the db or insert something the programm just freezes for some seconds and then i get the timeout error image of the error. One of the endpoints of the web-service that has a problem is this (i will also add the beginning of the file so you can see the connection with the db ):

from flask import Flask, request, Response, jsonify
import json
from pymongo import MongoClient
from datetime import date

client = MongoClient("mongodb://localhost:27017")

db=client["DigitalNotes"]
users=db["Users"]
admins=db["Admins"]
notes=db["Notes"]

app=Flask(__name__)


@app.route("/sign_up",methods=["POST"])
def sign_up():
    try:
        data=json.loads(request.data)
    except Exception as e:
        return Response("Bad json content",status=500,mimetype='application/json')
    if data==None:
        return Response("Bad request",status=500,mimetype='application/json')
    if not "email" in data or not "username" in data or not "name" in data or not "password" in data:
        return Response("Information incompleted",status=500,mimetype='application/json')
    
    if users.count_documents({"email":data["email"]})==0 or users.count_documents({"username":data["username"]})==0:
        user = {"email":data["email"],"username":data["username"],"name":data["name"],"password":data["password"]}
        users.insert_one(user)
        return Response(data["username"] " was added to the DataBase",status=200,mimetype='application/json')
    else:
        return Response("A user with the given username or password already exists",status=200,mimetype='application/json')

and the Dockerfile that creates the container is this:

FROM ubuntu:20.04
RUN apt-get update
RUN apt-get install -y python3 python3-pip
RUN pip3 install flask pymongo
RUN pip3 install datetime
RUN mkdir /app
COPY app.py /app/app.py
EXPOSE 5000
WORKDIR /app
ENTRYPOINT ["python3","-u","app.py"]

The container of the mongodb is created in an docker-compose file which is this:

version: '2'
services:
  mongodb:
    image: mongo
    restart: always
    container_name: mongodb
    ports:
    - 27017:27027
    volumes:
    - ./mongodb/data:/data/db
  flask-service:
    build:
      context: ./flask-service
    restart: always
    container_name: flask
    depends_on:
      - mongodb
    ports:
      - 5000:5000
    environment:
      - "MONGO_HOSTNAME=mongodb"

I just don't understand why it works fine locally and not in the containers. Can anyone please help??

CodePudding user response：

The connection string of MongoDb in flask container should be mongodb://mongodb:27017 because between containers you should specify the service name.