I've created a cluster with minikube

minikube start 

Applied this yaml manifest:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: gateway-deployment
spec:
  selector:
    matchLabels:
      app: gateway
  replicas: 1
  template:
    metadata:
      labels:
        app: gateway
    spec:
      containers:
      - name: gateway
        image: docker_gateway
        imagePullPolicy: Never
        ports:
        - containerPort: 4001
          protocol: TCP
---
apiVersion: v1
kind: Service
metadata:
  name: gateway
spec:
  selector:
    app: gateway
  ports:
  - protocol: TCP
    port: 4001

And my GO app in the container docker_gateway is just a gin http server with one route

package main
import "github.com/gin-gonic/gin"

func main() {
    r := gin.Default()
    r.GET("/hello", func(c *gin.Context) {
        c.JSON(200, gin.H{
            "message": "hello",
        })
    })

    server = &http.Server{
        Addr:    ":4001",
        Handler: r,
    }

    server.ListenAndServe()
}

In Postman I make requests to 192.168.252.130:4001/hello and get a responses

But Kubernetes Pod's logs in Kubernetes don't print those requests. I expect to get this:

[GIN] 2019/10/25 - 14:17:20 | 200 |       1.115µs |      192.168.252.1| GET      /hello

But an interesting thing is when I add Ingress

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: ingress
spec:
  backend:
    serviceName: gateway
    servicePort: 4001

I am able to make requests to 192.168.252.130/hello and 192.168.252.130:4001/hello And without the port Pod's logs print requests, but with the port - they don't.

[GIN] 2019/10/25 - 14:19:13 | 200 |       2.433µs |      192.168.252.1| GET      /hello