Websocket connection fails for internal communication within a Kubernetes container - node.js

Question

I am using Kubernetes to deploy my React Application. Due to the database, I am using (RethinkDB). I have to initiate a WebSocket connection between my React Application and a Node.js server that proxies to the Database instance. The connection works as intended when I deploy the Database instance, backend Node server and the react application in my local machine. However when I deploy the application in Kubernetes I receive the error
WebSocket connection to 'ws://localhost:8015/' failed: Error in connection establishment: net::ERR_CONNECTION_REFUSED
within my react application.
For further debugging, I executed a terminal within the container and ran curl command to the Service that connects to the Database and received no errors. I also ran the backend node server to see whether it connects to the remote database and saw no issues there. Finally, I tested whether the Backend server initiates the WebSocket as intended using wscat and the WebSocket connection is working. And due to the fact that the application runs well on my local machine, leads me to believe that there the issue in the React Application connecting to the WebSocket could be caused by how Kubernetes handles Websocket connections. Any clarification on the issue is gladly appreciated.
P.S
I Have added the backend server code, the code within the React application that connects to the WebSocket and the YAML files of my React+Backend Deployment. If any more files are required please feel free to comment
backend node server
const http = require('http');
var rethinkdbWebsocketServer = require('rethinkdb-websocket-server');
const httpServer = http.createServer();
rethinkdbWebsocketServer.listen({
httpServer: httpServer,
httpPath: '/',
dbHost: remoteDB_IP,
dbPort: 28015,
unsafelyAllowAnyQuery: true
});
httpServer.listen(8015);
React code that connects to the Websocket
ReactRethinkdb.DefaultSession.connect({
host: 'localhost', // the websocket server
port: process.env.REACT_APP_WEBSOCKET_PORT,
path: '/',
secure: false,
autoReconnectDelayMs: 2000, // when disconnected, millis to wait before reconnect
});
deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: dashboard
labels:
app: dashboard
spec:
replicas: 1
selector:
matchLabels:
app: dashboard
template:
metadata:
labels:
app: dashboard
spec:
containers:
- name: dashboard
image: myrepor/dashbaord
imagePullPolicy: Always
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
ports:
- containerPort: 3000
---
apiVersion: v1
kind: Service
metadata:
name: dashboard
spec:
selector:
app: dashboard
ports:
- port: 3000
targetPort: 3000
type: LoadBalancer

Answer 1

so kubernetes ideas is all about running each application in separate pod.
And connecting them through services.
This way you can deploy each layer separately without down time - service routes to old pod(s) until new are up and running. (and even more important scale up the separately )
Kubernetes does some kind of name resolution inside of each k8s cluster. Not exactly sure if that is a full dns or not
thus I would recommend
separate your node server into one pod. and deploy service for it with your ws port (8015).
your react app separate pod with its own service and define node server service name as endpoint for WS.
The reason is simple - not even sure that localhost going to be resolved correctly with in the pod.