Using Mongo Express connect to Mongodb via a service in Kubernetes does not require authentication?

[tdtu98]

In my project, I create a local k8s cluster using minikube. In this cluster, I deployed mongodb and mongo express with the configurations:

# mongo.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  labels:
    app: mongo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo
  template:
    metadata:
      labels:
        app: mongo
    spec:
      containers:
      - name: mongo
        image: arm64v8/mongo:latest
        ports:
        - containerPort: 27017
        env:
        - name: MONGO_INIT_ROOT_USERNAME
          value: admin
        - name: MONGO_INIT_ROOT_PASSWORD
          value: secret
---
apiVersion: v1
kind: Service
metadata: 
  name: mongodb-service
  labels:
    app: mongo
spec:
  selector:
    app: mongo
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

# mongo-express.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongo-express
  labels:
    app: mongo-express
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo-express
  template:
    metadata:
      labels:
        app: mongo-express
    spec:
      containers:
      - name: mongo-express
        image: arm64v8/mongo-express:latest
        ports:
        - containerPort: 8081
        env:
        - name: ME_CONFIG_MONGODB_URL
          value: "mongodb://mongodb-service:27017/"
---
apiVersion: v1
kind: Service
metadata: 
  name: mongo-express-service
spec:
  selector:
    app: mongo-express
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 8081
      targetPort: 8081
      nodePort: 30000

The next commands are:

kubectl apply -f mongo.yaml
kubectl apply -f mongo-express.yaml
minikube service [mongo-express-service]

I successfully connected to the mongodb deployment via mongodb-service using ME_CONFIG_MONGODB_URL:

- name: ME_CONFIG_MONGODB_URL
          value: "mongodb://mongodb-service:27017/"

The problem is even though I do not set any environment variable for username and password related to mongodb in mongo-express config, I can still connect to it.

[xTudoS]

but isn't it the default ?

screenshot from readme.md