This is an example documentation, you don't need to use the exact values provided in it.

You can set it up to any value you want, however setting up max-age and expires to too short periods of time, backend will be rebalanced too often. This the answer to another question - yes, ingress will rebalance the client.

There are two optional attributes you can use related to its age:

• Expires=<date>

Indicates the maximum lifetime of the cookie as an HTTP-date timestamp. In case of ingress, it's set up as a number.

• Max-Age=<number>

Indicates the number of seconds until the cookie expires. A zero or negative number will expire the cookie immediately.

Important! If both Expires and Max-Age are set, Max-Age has precedence.

Below is a working example with cookie max-age and expires set to 30 minutes:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-cookie-test
  annotations:
    nginx.ingress.kubernetes.io/affinity: "cookie"
    nginx.ingress.kubernetes.io/session-cookie-name: "test-cookie"
    nginx.ingress.kubernetes.io/session-cookie-expires: "1800"
    nginx.ingress.kubernetes.io/session-cookie-max-age: "1800"
spec:
  ingressClassName: nginx
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: service-name
            port:
              number: 80

And checking that it works performing a curl request (removed unnecessary details):

$ curl -I example.com
HTTP/1.1 200 OK
Date: Mon, 14 Mar 2022 13:14:42 GMT
Set-Cookie: test-cookie=1647263683.046.104.525797|ad50b946deebe30052b8573dcb9a2339; Expires=Mon, 14-Mar-22 13:44:42 GMT; Max-Age=1800; Path=/; HttpOnly