Unable to connect to mongo-express in Kubernetes cluster depending on the version tag

Question

I setup mongo-express in my local cluster and when connecting to it from localhost:8081 after successful authentication I see the message Turn on admin in config.js to view server statson the page. Searching for the issue I saw that it was related to the mongo-express:latest image I was using, and that mongo-express:0.54.0 should be used instead from SO question Turn on admin in config.js to view server stats, but with it it doesn't connect to it at all.

I also tried mongo-express:0.54 image but still not connecting, mongo-express:1.0.0-alpha.4 authorise fince but still shows the Turn on ... message.

mongo-express:latest logs

Welcome to mongo-express
------------------------


(node:7) [MONGODB DRIVER] Warning: Current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
Mongo Express server listening at http://0.0.0.0:8081
Server is open to allow connections from anyone (0.0.0.0)

mongo-express:0.54.0 logs

Waiting for mongo:27017...
/docker-entrypoint.sh: line 14: mongo: Name does not resolve
/docker-entrypoint.sh: line 14: /dev/tcp/mongo/27017: Invalid argument
Sun Jan 15 17:37:59 UTC 2023 retrying to connect to mongo:27017 (2/5)
/docker-entrypoint.sh: line 14: mongo: Name does not resolve
/docker-entrypoint.sh: line 14: /dev/tcp/mongo/27017: Invalid argument
Sun Jan 15 17:38:00 UTC 2023 retrying to connect to mongo:27017 (3/5)
/docker-entrypoint.sh: line 14: mongo: Name does not resolve
/docker-entrypoint.sh: line 14: /dev/tcp/mongo/27017: Invalid argument
Sun Jan 15 17:38:01 UTC 2023 retrying to connect to mongo:27017 (4/5)
/docker-entrypoint.sh: line 14: mongo: Name does not resolve
/docker-entrypoint.sh: line 14: /dev/tcp/mongo/27017: Invalid argument
Sun Jan 15 17:38:02 UTC 2023 retrying to connect to mongo:27017 (5/5)
/docker-entrypoint.sh: line 14: mongo: Name does not resolve
/docker-entrypoint.sh: line 14: /dev/tcp/mongo/27017: Invalid argument

I set ME_CONFIG_MONGODB_URL, ME_CONFIG_BASICAUTH_USERNAME and ME_CONFIG_BASICAUTH_PASSWORD mongo-express values getting them from the mongo-rs-fixit-admin-user secret that the operator creates by default which are correct as use them for connecting the node.js app to mongo. ME_CONFIG_MONGODB_ENABLE_ADMIN is set to true.

I deploy mongo db replica set with the community operator and by not specifying a service it will use the one that the operator creates by default. The operator also creates a secret containing the connection strings for mongo. Is there something I'm doing wrong? Many thanks for your time and help. Cheers

mongo service created by the operator

vincenzocalia@vincenzos-MacBook-Air kubernetes_yaml_files % kubectl describe svc mongo-rs-svc
Name:              mongo-rs-svc
Namespace:         default
Labels:            app=mongo-rs-svc
Annotations:       <none>
Selector:          app=mongo-rs-svc
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                None
IPs:               None
Port:              mongodb  27017/TCP
TargetPort:        27017/TCP
Endpoints:         10.1.0.79:27017,10.1.0.80:27017
Session Affinity:  None
Events:            <none>

mongo secret created by the operator

Name:         mongo-rs-fixit-admin-user
Namespace:    default
Labels:       <none>
Annotations:  <none>

Type:  Opaque

Data
====
connectionString.standardSrv:  108 bytes
password:                      8 bytes
username:                      10 bytes
connectionString.standard:     177 bytes

mongo deployment

apiVersion: mongodbcommunity.mongodb.com/v1
kind: MongoDBCommunity
metadata:
  name: mongo-rs
  namespace: default
spec:
  members: 2
  type: ReplicaSet
  # mongo version
  version: '5.0.5'
  security:
    authentication:
      modes:
        - SCRAM
  users:
    - name: admin-user

      db: fixit
      passwordSecretRef:
        name: mongo-secret
      roles:
        - name: clusterAdmin
          db: fixit
        - name: userAdminAnyDatabase
          db: fixit
      scramCredentialsSecretName: my-scram-mg-fixit
  additionalMongodConfig:
    storage.wiredTiger.engineConfig.journalCompressor: zlib
  statefulSet:
    spec:
      # You can specify a name for the service object created by the operator
      # if specified no connection strings are generated !!??
      # serviceName: mongo-rs-svc
      # get them with kubectl -n default get secret mongo-rs-fixit-admin-user -o json  and then decode them with echo "value" | base64 -d
      
      template:
        spec:
          affinity:
            podAntiAffinity:
              requiredDuringSchedulingIgnoredDuringExecution:
                - labelSelector:
                    matchExpressions:
                      - key: app
                        operator: In
                        values:
                          - mongo-replicaset
                  topologyKey: 'kubernetes.io/hostname'

      volumeClaimTemplates:
        - metadata:
            name: data-volume
          spec:
            accessModes:
              - ReadWriteOnce
              # - ReadWriteMany
            storageClassName: mongo-sc-data
            resources:
              requests:
                storage: 10Gi
        - metadata:
            name: logs-volume
          spec:
            accessModes:
              - ReadWriteOnce
              # - ReadWriteMany
            storageClassName: mongo-sc-logs
            resources:
              requests:
                storage: 2Gi

mongo-express deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: mongo-express
  name: mongo-express
  namespace: default
spec:
  selector:
    matchLabels:
      app: mongo-express
  template:
    metadata:
      labels:
        app: mongo-express
    spec:
      containers:
        - name: mongo-express
          # image: mongo-express # connects but Turn on admin in config.js to view server stats!
          # image: mongo-express:latest # connects but  Turn on admin in config.js to view server stats!
          image: mongo-express:0.54.0
          # image: mongo-express:0.54
          imagePullPolicy: 'Always'
          ports:
            - containerPort: 8081
              protocol: TCP

          resources:
            limits:
              memory: '1Gi'
              cpu: '100m'
          env:
            # - name: ME_CONFIG_MONGODB_SERVER
            # value: mongo-rs-0.mongo-rs-svc.default.svc.cluster.local
            - name: ME_CONFIG_MONGODB_URL
              valueFrom:
                secretKeyRef:
                  name: mongo-rs-fixit-admin-user
                  key: connectionString.standard
            - name: ME_CONFIG_MONGODB_ENABLE_ADMIN
              value: 'true'
            - name: ME_CONFIG_BASICAUTH_USERNAME
              valueFrom:
                secretKeyRef:
                  name: mongo-rs-fixit-admin-user
                  key: username
            - name: ME_CONFIG_BASICAUTH_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongo-rs-fixit-admin-user
                  key: password
      restartPolicy: 'Always'

mongo-express service

apiVersion: v1
kind: Service
metadata:
  labels:
    app: mongo-express
  name: mongo-express
  namespace: default
spec:
  ports:
    - name: http
      port: 8081
      targetPort: 8081
      protocol: TCP
  selector:
    app: mongo-express
  type: LoadBalancer
``