connecting scrapy container to mongo container

Question

I am trying to spin and connect two containers (mongo and scrapy spider) using docker-compose. Being new to Docker I've had a hard time troubleshooting networking ports (inside and outside the container). To respect your time I'll keep it short.

The problem:

Can't connect the spider to the mongo db container and get a timeout error. I think it has to with the IP address that I am trying to connect to from the container is incorrect. However, the spider works locally (non-dockerized version) and can pass data to a running mongo container.

small edit to remove name and email from code.

error:

pymongo.errors.ServerSelectionTimeoutError: 127.0.0.1:27017: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 5feb8bdcf912ec8797c25497, topology_type: Single

pipeline code:

from scrapy.exceptions import DropItem
# scrappy log is deprecated
#from scrapy.utils import log
import logging
import scrapy
from itemadapter import ItemAdapter
import pymongo

class xkcdMongoDBStorage:
    """
    Class that handles the connection of 
    Input:
        MongoDB
    Output
    """
    def __init__(self):
        # requires two arguments(address and port)
        #* connecting to the db
        self.conn = pymongo.MongoClient(
            '127.0.0.1',27017) # works with spider local and container running
            # '0.0.0.0',27017)
        # connecting to the db
        dbnames = self.conn.list_database_names()
        if 'randallMunroe' not in dbnames:
            # creating the database
            self.db = self.conn['randallMunroe']

        #if database already exists we want access
        else:
            self.db = self.conn.randallMunroe
        #* connecting to the table
        dbCollectionNames = self.db.list_collection_names()
        if 'webComic' not in dbCollectionNames:
            self.collection = self.db['webComic']
        
        else:
            # the table already exist so we access it
            self.collection = self.db.webComic

    def process_item(self, item, spider):
        valid = True
        for data in item:
            if not data:
                valid = False
                raise DropItem("Missing {0}!".format(data))
        if valid:
            self.collection.insert(dict(item))
            logging.info(f"Question added to MongoDB database!")
        return item

Dockerfile for the spider

# base image
FROM python:3
# metadata info
LABEL maintainer="first last name" email="something@gmail.com"
# exposing container port to be the same as scrapy default
EXPOSE 6023
# set work directly so that paths can be relative
WORKDIR /usr/src/app
# copy to make usage of caching
COPY requirements.txt ./
#install dependencies
RUN pip3 install --no-cache-dir -r requirements.txt
# copy code itself from local file to image
COPY . .
CMD scrapy crawl xkcdDocker

version: '3'
services:
  db:
    image: mongo:latest
    container_name: NoSQLDB
    restart: always
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: password
    volumes:
      - ./data/bin:/data/db
    ports:
      - 27017:27017
    expose:
      - 27017

  xkcd-scraper:
    build: ./scraperDocker
    container_name: xkcd-scraper-container
    volumes: 
      - ./scraperDocker:/usr/src/app/scraper
    ports:
      - 5000:6023
    expose:
      - 6023
    depends_on:
      - db

Thanks for the help

Answer 1

Try:

self.conn = pymongo.MongoClient('NoSQLDB',27017)

Within docker compose you reference other containers based on the service name.