Mongodb Authentication failed in Kubernetes (minikube)

Creating a mongodb from the below minikube deployment, I am not able to authenticate from the command line.

Basically I'd just want to list all databases because I suspect there is an issue with the connectivity to mongo-express.

I exec into the pod using kubectl exec -it mongodb-deployment-6b46455744-gfkzw -- /bin/bash,

mongo to start up the cli

db.auth("username", "password") gives MongoServerError: Authentication failed.

even though printenv gives

MONGO_INITDB_ROOT_PASSWORD=password
MONGO_INITDB_ROOT_USERNAME=username

any help?

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
      - name: mongodb
        image: mongo
        ports:
        - containerPort: 27017
        env:
        - name: MONGO_INITDB_ROOT_USERNAME
          valueFrom:
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-username
        - name: MONGO_INITDB_ROOT_PASSWORD
          valueFrom: 
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-password
        - name: ME_CONFIG_MONGODB_ENABLE_ADMIN
          value: "true"
---
apiVersion: v1
kind: Service
metadata:
  name: mongodb-service
spec:
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017