To load balance a WebSocket application with NGINX Ingress controllers, you need to add the nginx.org/websocket-services annotation to your Ingress resource definition. The annotation specifies which services are websocket services. The annotation syntax is as follows:

nginx.org/websocket-services: "service1[,service2,...]"

In the following example we load balance three applications, one of which is using WebSocket:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: cafe-ingress
  annotations:
    nginx.org/websocket-services: "ws-svc"
spec:
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /tea
        backend:
          serviceName: tea-svc
          servicePort: 80
      - path: /coffee
        backend:
          serviceName: coffee-svc
          servicePort: 80
      - path: /ws
        backend:
          serviceName: ws-svc
          servicePort: 8008

ws-svc is a service for the WebSocket application. The service becomes available at the /ws path. Note how we used the nginx.org/websocket-services annotation.