I have an applications Docker image which starts a mongodb instance on a random port. When I create a kubernetes Pod with application image; application gets successfully initialized and a mongodb instance gets up on a random port as localhost:port without any error.

However, when I create a Kubernetes Deployment; the same application initialization fails inside the container with error "mongodb can not be started as localhost:port can not be accessed".

If anyone can explain, why application initialization is failing with K8-Deployment but not with K-8Pod? And, How can I resolve this problem?

apiVersion: apps/v1
kind: Pod
metadata:
  name: my-app
spec:
  containers:
  - name: my-app
    image: my-app:v1
    ports:
    - containerPort: 8888 # Apps exposed port

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  labels:
    app: my-dep
spec:
  replicas: 2
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-app
        image: my-app:v1
        ports:
        - containerPort: 8888 # Apps exposed port

Thanks