kong router prefix matching different behavior due to regex_priority

[jiachinzhao]

there are 2 route rule.

route1:
{ "hosts": ["foo.com"], "paths": ["/"], "regex_priority": 1 }

route2:
{ "hosts": ["foo.com"] "paths": ["/v1"], "regex_priority": 0 }

the following request will route to route2, correct behavior due to prefix matching choosing longest length.

GET /v1/xxx   HTTP/1.1
Host: foo.com

however, after adding another route things changed.
route3:
{ "hosts": ["bar.com"], "paths": ["/.*"], "regex_priority": 0 }

the same request will route to route1, which is an unexpected route behavior.

when I remove regex_priority from route1 and route2, the behavior is corret。

I think regex_priority cannot be used for routing rule sorting when using prefix matching which will sometimes make a mistake.

tested on Kong version 2.1.4
the behavior still exists on the latest version

[kikito]

when I remove regex_priority from route1 and route2, the behavior is corret。

That ... doesn't seem to be correct. ´regex_priority´ is used to disambiguate between two requests that both have regexes. In your example only one of them (route3) has regexes, so regex_priority should play no role.

Could you please provide a full list of the calls you are using, so we can reproduce?

Related:

• kong proxy match order #4121
• https://discuss.konghq.com/t/a-few-words-on-regex-uris-usage-and-common-pitfalls/506

[jiachinzhao]

it can be easily reproduce on k8s
kong ingress controller 0.9.0
kong 2.1.4
apply 2 service and 3 ingress rules.

apiVersion: v1
kind: Service
metadata:
  name: my-service1
spec:
  selector:
    app: MyApp
  ports:
    - protocol: TCP
      port: 8080
      targetPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: my-service2
spec:
  selector:
    app: MyApp
  ports:
    - protocol: TCP
      port: 8080
      targetPort: 8080
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: route1
  annotations:
    kubernetes.io/ingress.class: kong-test
    konghq.com/regex-priority: "1"
spec:
  rules:
    - host: foo.com
      http:
        paths:
          - path: /
            backend:
              serviceName: my-service1
              servicePort: 8080
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: route2
  annotations:
    kubernetes.io/ingress.class: kong-test
    konghq.com/regex-priority: "0"
spec:
  rules:
    - host: foo.com
      http:
        paths:
          - path: /v1
            backend:
              serviceName: my-service1
              servicePort: 8080
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: route3
  annotations:
    kubernetes.io/ingress.class: kong-test
spec:
  rules:
    - host: bar.com
      http:
        paths:
          - path: /.*
            backend:
              serviceName: my-service2
              servicePort: 8080

http request with kong_debug

curl -I -H 'kong_debug: true'  -H 'host: foo.com'  ${kong_pod_ip}:8080/v1/pong 
the  route_id will be different in response_header  between ingress route3 apply or not。
ingress route3 apply:   route_id belong to route1
ingress route3 delete:  route_id belong to route2