On a GKE cluster, I have client and server pods, with a client service and a server service.
My server service is:
apiVersion: v1
kind: Service
metadata:
name: server-cluster-ip-service
spec:
type: ClusterIP
selector:
app: server-deployment
ports:
- port: 5000
targetPort: 5000
When I access the client pod shell and run
nslookup server-cluster-ip-service
I get
Server: server-IP
Address: server-IP-Address
Name: server-cluster-ip-service.default.svc.cluster.local
Address: IPAddress
** server can't find server-cluster-ip-service.svc.cluster.local: NXDOMAIN
** server can't find server-cluster-ip-service.cluster.local: NXDOMAIN
** server can't find server-cluster-ip-service.svc.cluster.local: NXDOMAIN
** server can't find server-cluster-ip-service.cluster.local: NXDOMAIN
** server can't find server-cluster-ip-service.us-central1-c.c.my-cluster.internal: NXDOMAIN
** server can't find server-cluster-ip-service.google.internal: NXDOMAIN
** server can't find server-cluster-ip-service.us-central1-c.c.my-cluster: NXDOMAIN
** server can't find server-cluster-ip-service.google.internal: NXDOMAIN
** server can't find server-cluster-ip-service.c.my-cluster.internal: NXDOMAIN
** server can't find server-cluster-ip-service.c.my-cluster.internal: NXDOMAIN
The service is running on port 5000, because when I set up a pod with busybox, I can curl from that pod like so:
curl server-cluster-ip-service:5000
And it returns json from my server.
After experimenting with what address to put in the fetch request in my client code, the only way I can get a 200 response is with this:
const getAllUsers = async () => {
console.log("GETTING ALL USERS");
const response = await fetch("server-cluster-ip-service.default.svc.cluster.local", {
mode: 'cors',
headers: {
'Access-Control-Allow-Origin':'*'
}
});
const resp = await response
console.log("RESPONSE", resp)
const json = await response.json();
setUsers(json);
};
which returns not json and not apparently on port 5000,
whereas all attempts to query the service at port 5000 fail.
I have this running locally and it works fine. I have ruled out arm processor issues with my mac by building and pushing docker images in GKE from the cloud console. I am fairly confident this is a GKE issue, because the dns works locally, but why would it not work with GKE? I don't have any network policies I've set myself - could there be a node security group blocking access? I read about "shielding" as a node security policy configured at setup, but I don't know how to check if that's been configured?
Complete code below:
My server code is:
const express = require("express");
const bodyParser = require("body-parser");
var cors = require("cors");
const PORT = 5000;
const app = express();
app.use(cors());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(express.static("public"));
app.listen(PORT, function () {
console.log("listening on 5000");
});
app.get("/", (req, res) => {
console.log("PROCESSING GET USERS REQUEST");
const list = ["item1", "item2", "item3"];
res.json(list);
});
My client code is:
import { useState, useEffect } from "react";
import "./editUser.css";
function EditUser() {
const [users, setUsers] = useState([]);
const getAllUsers = async () => {
console.log("GETTING ALL USERS");
const response = await fetch("http://server-cluster-ip-service:5000");
const json = await response.json();
setUsers(json);
};
useEffect(() => {
getAllUsers();
}, []);
return (
<div className="App">
<h1 data-position="header">Merr k8s testbed</h1>
<section data-position="quotes">
<h2>Console</h2>
<ul>
{users &&
users.map((user) => (
<li>
<h3>{user}</h3>
</li>
))}
</ul>
</section>
</div>
);
}
export default EditUser;
My client-deployment.yaml is:
kind: Deployment
metadata:
name: client-deployment
labels:
app: client-deployment
component: web
spec:
replicas: 3
selector:
matchLabels:
app: client-deployment
template:
metadata:
labels:
app: client-deployment
component: web
spec:
containers:
- name: client
image: myDocker/k8s-client:latest
ports:
- containerPort: 3000
My server-deployment.yaml is:
apiVersion: apps/v1
kind: Deployment
metadata:
name: server-deployment
labels:
app: server-deployment
spec:
replicas: 3
selector:
matchLabels:
app: server-deployment
template:
metadata:
labels:
app: server-deployment
spec:
containers:
- name: server
image: myDocker/k8s-server:latest
ports:
- containerPort: 5000
My client-cluster-ip-service.yaml is:
apiVersion: apps/v1
kind: Deployment
metadata:
name: server-deployment
labels:
app: server-deployment
spec:
replicas: 3
selector:
matchLabels:
app: server-deployment
template:
metadata:
labels:
app: server-deployment
spec:
containers:
- name: server
image: myDocker/k8s-server:latest
ports:
- containerPort: 5000
My server-cluster-ip-service.yaml is:
apiVersion: v1
kind: Service
metadata:
name: server-cluster-ip-service
spec:
type: ClusterIP
selector:
app: server-deployment
ports:
- port: 5000
targetPort: 5000
