1. Problem Description

I'm trying to run a MongoDB Deployment + Service on Kubernetes where other Pods/Jobs or Containers could access it. So far I have apparently been successful at deploying it, however whenever I try to access it from within a Job, Pod or Container, I get (note that I'm using 0.0.0.0 instead of localhost in order to access the host machine; and that my timeout is 30 seconds):

pymongo.errors.ServerSelectionTimeoutError: 0.0.0.0:30001: [Errno 111] Connection refused

2. Locally, it seems to work...

If I try to access it through a Python CLI, it does look like it works though:

>>> import pymongo
>>> client = pymongo.MongoClient(host='0.0.0.0', port=30001) # 'localhost' also works
>>> client.list_database_names()
['admin', 'config', 'local', 'test_db'] # 'test_db' is a db I had previously created

Should I use another host address when trying to access the MongoDB service? (If so, where does it show on kubectl describe svc <service_name>?)

3. Deployment and Service Configurations

My MongoDB deployment (adapted from Nigel Poulton's Kubernetes Book) is:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mymongodb-dep
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hello-mongo
  minReadySeconds: 10
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  template:
    metadata:
      labels:
        app: hello-mongo
    spec:
      containers:
      - name: mongo
        image: mongo
        imagePullPolicy: IfNotPresent
        ports:
            - containerPort: 27017

And its service is:

apiVersion: v1
kind: Service
metadata:
  name: hello-svc
  labels:
    app: hello-mongo
spec:
  type: NodePort
  ports:
  - port: 27017
    nodePort: 30001
    protocol: TCP
  selector:
    app: hello-mongo