Regex doesnt work after kong upgrade to version 3.x

Regex doesnt work after kong upgrade to version 3.x.

After upgrading from kong 2.7 to 3.2, regex stopped working.

Regex pattern used in 2.7: /payment/(docs|health)

Regex pattern used in 3.2: /~payment/(docs|health)

Also tried to use ~/payment/(docs|health), but it gives error as in screenshot

Pathtype is ImplementationSpecific

- apiVersion: networking.k8s.io/v1
  kind: Ingress
  metadata:
    labels:
      app.kubernetes.io/name: payment-svc
    name: payment-without-auth
    namespace: payment
  spec:
    ingressClassName: kong
    rules:
    - host: abc.example.com
      http:
        paths:
        - backend:
            service:
              name: payment-svc
              port:
                number: 80
          path: /payment/(docs|health)
          pathType: ImplementationSpecific

Tried couple if regex changes.

To complement @kranthiveer-dontineni's answer, you'll need the /~ prefix in kubernetes manifests to make this work

> Ingress paths that begin with /~ are now treated as regular
> expressions, and are translated into a Kong route path that begins
> with ~ instead of /~. To preserve the existing translation, set
> konghq.com/regex-prefix to some value. For example, if you set
> konghq.com/regex-prefix: /@, paths beginning with /~ will result in
> route paths beginning in /~, whereas paths beginning in /@ will result
> in route paths beginning in ~. #2956

https://github.com/Kong/kubernetes-ingress-controller/blob/main/CHANGELOG.md#breaking-changes-1

If you have upgraded your kong deployment from 2.8.X to 3.0 the prefix(~) will be added to the routes in the database automatically and results in a configuration drift between the routes database and config file, as per the official documentation.

Before using your state files to update the database, convert them into the 3.0 format using the deck convert command.

Important: Don’t use deck sync with Kong Gateway 3.x before converting paths into the 3.0 format. This will break all regex routing in 3.x.

Run deck-convert against your 2.x state file to turn it into a 3.x file:

deck convert --from kong-gateway-2.x --to kong-gateway-3.x --input-file kong.yaml --output-file new-kong.yaml

Note: This content is taken from official kong documentation. Refer to this link for more information.