Aws-load-balancer-controller: websockets support

[rmrbest]

I would like to know if we have support for websockets. Which steps to do it? Any annotations?

[tomhughesnice]

The AWS ALB supported websockets from the beginning. https://aws.amazon.com/blogs/aws/new-aws-application-load-balancer/

[rmrbest]

Yes, but when you have N replicas deployed, i've a problem, because i receive a 400 error handshake some times.

[rmrbest]

I fixed adding sessionAffinity on my service definition as ClientIP.

It works now, without session id unknown message error in the polling requests.

[ricardohsd]

Hi @rmrbest I'm curious in how you fixed it. I've checked and ingress doesn't provide sessionAffinity option.

[sohan]

@ricardohsd you define sessionAffinity on your service's spec:

apiVersion: v1
kind: Service
metadata:
  ...
spec:
  type: NodePort
  sessionAffinity: ClientIP

[sohan]

Actually I'm also seeing handshake errors even with sessionAffinity: ClientIP. The error happens when socketio tries to upgrade its transport from polling to websockets.

If I enable stickiness in the ALB the errors mostly go away. However, I still get the handshake 400 errors, just less frequently/reproducibly.

Would anyone have ideas for how to debug this? I'm not sure I understand why sessionAffinity: ClientIP is not enough and stickiness needs to be enabled at all.

cc @rmrbest would you be able to share your exact set up and manifests? Thanks!

[vrathore18]

@sohan : are you able to solve the issue?? could someone provide the solution.

[sohan]

@vrathore18 I wasn't able to solve this issue. We worked around it instead by disabling the polling transport for socket.io. I.e. on our clients, we use:

const io = require('socket.io-client');
const socket = io(path, { transports: ['websocket'] });

I also removed the sessionAffinity setting from our service.

[M00nF1sh]

@sohan I have posted instructions on how to use websocket/socket.io in https://github.com/kubernetes-sigs/aws-alb-ingress-controller/issues/1090, socket.io is not websocket