Cannot access the IP create by google kubernetes engine (GKE) after exposing it as service

Question

I have an app which will start a server at 127.0.0.1:8080 and using a Dockerfile to create an image for hosting it on GKE. I deployed this app on port 8080 on the kube.netes cluster. Then I EXPOSE the service as LoadBalancer for the same port 8080 but it is not allowing it to be accessed from outside. So I created an ingress for external access but still doesn't work. When I click at the IP provided by ingress, I get this Error:

Error: Server Error
The server encountered a temporary error and could not complete your request.
Please try again in 30 seconds.

I would like to ask is there something I have missed or done wrong in the implementation.

My YAML file:

---
apiVersion: "apps/v1"
kind: "Deployment"
metadata:
  name: "app"
  namespace: "default"
  labels:
    app: "app"
spec:
  replicas: 3
  selector:
    matchLabels:
      app: "app"
  template:
    metadata:
      labels:
        app: "app"
    spec:
      containers:
      - name: "app-sha256-1"
        image: "gcr.io/project-1234/github.com/user/app@sha256:b17b8159668d44fec3d"
---
apiVersion: "autoscaling/v2beta1"
kind: "HorizontalPodAutoscaler"
metadata:
  name: "app-hpa-y3ay"
  namespace: "default"
  labels:
    app: "app"
spec:
  scaleTargetRef:
    kind: "Deployment"
    name: "app"
    apiVersion: "apps/v1"
  minReplicas: 1
  maxReplicas: 5
  metrics:
  - type: "Resource"
    resource:
      name: "cpu"
      targetAverageUtilization: 80

---
apiVersion: "v1"
kind: "Service"
metadata:
  name: "app-service"
  namespace: "default"
  labels:
    app: "app"
spec:
  ports:
  - protocol: "TCP"
    port: 8080
  selector:
    app: "app"
  type: "LoadBalancer"
  loadBalancerIP: ""

---
apiVersion: "extensions/v1beta1"
kind: "Ingress"
metadata:
  name: "ingress"
  namespace: "default"
spec:
  backend:
    serviceName: "app-service"
    servicePort: 8080

Thanks. Look forward to the suggestions.

Answer 1

start a server at 127.0.0.1:8080 this would allow your app to accept connection within the pod only. Bind to 0.0.0.0 instead.

Also your Deployment:

...
containers:
  - name: "app-sha256-1"
    image: "gcr.io/project-1234/github.com/user/app@sha256:b17b8159668d44fec3d"
    ports:
    - containerPort: <the port# that your container serves>

And your Service:

...
ports:
- protocol: "TCP"
  port: 8080
  targetPort: <the port that your container serves>