Release 0.34.0 Break Regex Paths

[jzhang046]

NGINX Ingress controller version: 0.34.0

Kubernetes version (use kubectl version): v1.9.6

What happened:
With #5691 merged and released in 0.34.0, following issues have occurred:

• The behaviour is not consistent with the documentation, in which it says that

If the use-regex OR rewrite-target annotation is used on any Ingress for a given host, then the case insensitive regular expression location modifier will be enforced on ALL paths for a given host regardless of what Ingress they are defined on.

• Regex path does not work with only nginx.ingress.kubernetes.io/rewrite-target annotation. Seems like additional nginx.ingress.kubernetes.io/use-regex annotation has to be applied in order for regex path to work.
• @zrdaley has made a great example of why it was necessary to apply regex to all locations: use-regex annotation should be applied to only one Location #5691 (comment). Directly upgrading to 0.34.0 from 0.33.0 will make ingress resources behave differently.

What you expected to happen:
Keep the existing behaviour until 0.33.0 and apply regex to all locations

How to reproduce it:

• Install the ingress controller

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/baremetal/deploy.yaml

• Install an application that will act as default backend (is just an echo app)

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/docs/examples/http-svc.yaml

• Create an ingress (please add any additional annotation required)

echo "
  apiVersion: networking.k8s.io/v1beta1
  kind: Ingress
  metadata:
    name: foo-bar
  spec:
    rules:
    - host: foo.bar
      http:
        paths:
        - backend:
            serviceName: http-svc
            servicePort: 80
          path: /
" | kubectl apply -f -

echo "
  apiVersion: networking.k8s.io/v1beta1
  kind: Ingress
  metadata:
    name: foo-bar-rewrite
    annotations: 
      nginx.ingress.kubernetes.io/rewrite-target: /\$1
  spec:
    rules:
    - host: foo.bar
      http:
        paths:
        - backend:
            serviceName: http-svc
            servicePort: 80
          path: /foo/bar/(.+)
" | kubectl apply -f -

• make a request

POD_NAME=$(kubectl get pods -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx -o NAME)
kubectl exec -it -n ingress-nginx $POD_NAME -- curl -H 'Host: foo.bar' localhost/foo/bar/123

• expected result

Request Information:
        client_address=172.18.0.5
        method=GET
        real path=/123
        query=
        request_version=1.1
        request_scheme=http
        request_uri=http://foo.bar:8080/123

• actual result

Request Information:
        client_address=172.18.0.5
        method=GET
        real path=/foo/bar/123
        query=
        request_version=1.1
        request_scheme=http
        request_uri=http://foo.bar:8080/foo/bar/123

• temporary fix to get expected result

echo "
  apiVersion: networking.k8s.io/v1beta1
  kind: Ingress
  metadata:
    name: foo-bar-rewrite
    annotations: 
      nginx.ingress.kubernetes.io/use-regex: \"true\"
      nginx.ingress.kubernetes.io/rewrite-target: /\$1
  spec:
    rules:
    - host: foo.bar
      http:
        paths:
        - backend:
            serviceName: http-svc
            servicePort: 80
          path: /foo/bar/(.+)
" | kubectl apply -f -

Anything else we need to know: N. A.

/kind bug

[aledbf]

@jzhang046 we just release 0.34.1 reverting that change. I am adding new e2e tests to avoid this problem in the future