I deploy nifi and gloo API Gateway on the same GKE cluster. The external IP exposed as LoadBalancer work well (open on Web browser or telnet). However, when I use telnet to connect gloo API Gateway on GKE cloud shell, my connection was refused.

Depends on relational causes and solutions, I have allow traffic to flow into cluster by creating firewall rule:

gcloud compute firewall-rules create my-rule --allow=all

How can I do for it?

kubectl get -n gloo-system service/gateway-proxy-v2 -o yaml

apiVersion: v1
kind: Service
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"gloo","gateway-proxy-id":"gateway-proxy-v2","gloo":"gateway-proxy"},"name":"gateway-proxy-v2","namespace":"gloo-system"},"spec":{"ports":[{"name":"http","port":80,"protocol":"TCP","targetPort":8080},{"name":"https","port":443,"protocol":"TCP","targetPort":8443}],"selector":{"gateway-proxy":"live","gateway-proxy-id":"gateway-proxy-v2"},"type":"LoadBalancer"}}
  labels:
    app: gloo
    gateway-proxy-id: gateway-proxy-v2
    gloo: gateway-proxy
  name: gateway-proxy-v2
  namespace: gloo-system
spec:
  clusterIP: 10.122.10.215
  externalTrafficPolicy: Cluster
  ports:
  - name: http
    nodePort: 30189
    port: 80
    protocol: TCP
    targetPort: 8080
  - name: https
    nodePort: 30741
    port: 443
    protocol: TCP
    targetPort: 8443
  selector:
    gateway-proxy: live
    gateway-proxy-id: gateway-proxy-v2
  sessionAffinity: None
  type: LoadBalancer
status:
  loadBalancer:
    ingress:
    - ip: 34.xx.xx.xx

kubectl get svc -n gloo-system

NAME               TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE
gateway-proxy-v2   LoadBalancer   10.122.10.215   34.xx.xx.xx   80:30189/TCP,443:30741/TCP   63m
gloo               ClusterIP      10.122.5.253    <none>        9977/TCP                     63m