ingress-nginx: nginx /healthz endpoint breaks when using an ingress with nginx.ingress.kubernetes.io/rewrite-target without a host

What happened:

When creating an ingress without a host, and using nginx.ingress.kubernetes.io/rewrite-target: /$2 the /healthz endpoint no longer works it give a 404

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: webserver
  namespace: namespace
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
    nginx.ingress.kubernetes.io/configuration-snippet: |
      more_set_input_headers "x-request-start: t=$msec";
spec:
  rules:
    - http:
        paths:
          - path: /webserver(/|$)(.*)
            pathType: Prefix
            backend:
              service:
                name: webserver
                port:
                  number: 8000

❯ curl -Is https://clusterdns.name/healthz
HTTP/1.1 404 Not Found

What you expected to happen:

I would expect the default /healthz endpoint to not be affected

NGINX Ingress controller version (exec into the pod and run nginx-ingress-controller --version.):

-------------------------------------------------------------------------------
NGINX Ingress controller
  Release:       v1.2.1
  Build:         08848d69e0c83992c89da18e70ea708752f21d7a
  Repository:    https://github.com/kubernetes/ingress-nginx
  nginx version: nginx/1.19.10

-------------------------------------------------------------------------------

Kubernetes version (use kubectl version):

❯ kubectl version
Client Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.1", GitCommit:"86ec240af8cbd1b60bcc4c03c20da9b98005b92e", GitTreeState:"clean", BuildDate:"2021-12-16T11:33:37Z", GoVersion:"go1.17.5", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.5", GitCommit:"5a97ee6d15525f6e4a1c2646bf1dfd2ebd5220b5", GitTreeState:"clean", BuildDate:"2022-06-15T04:26:33Z", GoVersion:"go1.17.8", Compiler:"gc", Platform:"linux/amd64"}

Environment:

• Cloud provider or hardware configuration: – Azure
• OS (e.g. from /etc/os-release):

NAME="Ubuntu"
VERSION="18.04.6 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.6 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

• Kernel (e.g. uname -a):

Linux aks-pool1az0-16738398-vmss00001A 5.4.0-1083-azure #87~18.04.1-Ubuntu SMP Fri Jun 3 13:19:07 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

• Install tools:
  • Please mention how/where was the cluster created like kubeadm/kops/minikube/kind etc.
    • terraform. AKS
• Basic cluster related info:
  • kubectl version

Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.5", GitCommit:"5a97ee6d15525f6e4a1c2646bf1dfd2ebd5220b5", GitTreeState:"clean", BuildDate:"2022-06-15T04:26:33Z", GoVersion:"go1.17.8", Compiler:"gc", Platform:"linux/amd64"}

• kubectl get nodes -o wide

❯ kubectl get nodes -o wide
NAME                               STATUS   ROLES   AGE   VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION     CONTAINER-RUNTIME
aks-pool0-34788694-vmss000000      Ready    agent   21d   v1.23.5   10.101.64.4     <none>        Ubuntu 18.04.6 LTS   5.4.0-1083-azure   containerd://1.5.11+azure-2
aks-pool1az0-16738398-vmss00001a   Ready    agent   21d   v1.23.5   10.101.65.246   <none>        Ubuntu 18.04.6 LTS   5.4.0-1083-azure   containerd://1.5.11+azure-2
aks-pool1az0-16738398-vmss00001y   Ready    agent   21d   v1.23.5   10.101.64.253   <none>        Ubuntu 18.04.6 LTS   5.4.0-1083-azure   containerd://1.5.11+azure-2
aks-pool1az0-16738398-vmss00002b   Ready    agent   21d   v1.23.5   10.101.67.232   <none>        Ubuntu 18.04.6 LTS   5.4.0-1083-azure   containerd://1.5.11+azure-2
aks-pool1az0-16738398-vmss00002c   Ready    agent   21d   v1.23.5   10.101.70.211   <none>        Ubuntu 18.04.6 LTS   5.4.0-1083-azure   containerd://1.5.11+azure-2
aks-pool1az0-16738398-vmss00002h   Ready    agent   21d   v1.23.5   10.101.66.239   <none>        Ubuntu 18.04.6 LTS   5.4.0-1083-azure   containerd://1.5.11+azure-2

• How was the ingress-nginx-controller installed:
  • If helm was used then please show output of helm ls -A | grep -i ingress
  • If helm was used then please show output of helm -n <ingresscontrollernamepspace> get values <helmreleasename>
  • If helm was not used, then copy/paste the complete precise command used to install the controller, along with the flags and options used
  • if you have more than one instance of the ingress-nginx-controller installed in the same cluster, please provide details for all the instances it was installed using kustomize flags

apiVersion: v1
data:
  brotli-level: "4"
  disable-access-log: "false"
  disable-ipv6: "true"
  disable-ipv6-dns: "true"
  enable-brotli: "true"
  enable-ocsp: "true"
  enable-opentracing: "true"
  gzip-level: "2"
  hsts: "true"
  hsts-include-subdomains: "true"
  hsts-max-age: "31556952"
  jaeger-endpoint: http://otel-collector.ingress-nginx.svc.cluster.local:14268/api/traces
  jaeger-propagation-format: w3c
  load-balance: ewma
  log-format-escape-json: "true"
  log-format-upstream: '{\"time\":\"$time_iso8601\",\"remote_addr\":\"$proxy_protocol_addr\",\"x_forward_for\":\"$proxy_add_x_forwarded_for\",\"request_id\":\"$req_id\",\"ingress\":\"$namespace/$ingress_name\",\"bytes_sent\":\"$bytes_sent\",\"upstream\":\"$proxy_upstream_name\",\"upstream_server\":\"$upstream_addr\",\"status\":\"$status\",\"vhost\":\"$host\",\"request_proto\":\"$server_protocol\",\"path\":\"$uri\",\"request_query\":\"$args\",\"request_length\":\"$request_length\",\"duration\":\"$request_time\",\"method\":\"$request_method\",\"http_referrer\":\"$http_referer\",\"http_user_agent\":\"$http_user_agent\",\"message\":\"$request_method
    $host$uri $server_protocol $status\"}'
  nginx-status-ipv4-whitelist: 10.101.64.0/18
  proxy-body-size: 20m
  proxy-buffering: "off"
  proxy-connect-timeout: "1"
  proxy-next-upstream: error timeout invalid_header http_502 http_503
  proxy-next-upstream-timeout: "30"
  proxy-next-upstream-tries: "3"
  proxy-read-timeout: "30"
  reuse-port: "true"
  ssl-ciphers: ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384
  ssl-early-data: "true"
  ssl-protocols: TLSv1.3 TLSv1.2
  ssl-redirect: "false"
  ssl-session-cache-size: 100m
  upstream-keepalive-connections: "320"
  upstream-keepalive-requests: "10000"
  upstream-keepalive-timeout: "60"
  use-geoip: "false"
  use-geoip2: "false"
  use-gzip: "true"
  use-http2: "true"
  worker-processes: "3"
  worker-shutdown-timeout: 240s
kind: ConfigMap
metadata:
  labels:
    app: nginx-ingress-controller
    app.kubernetes.io/component: controller
    app.kubernetes.io/instance: ingress-nginx
    app.kubernetes.io/version: 1.2.1
  name: nginx-configuration
  namespace: ingress-nginx

deployment flags

    containers:
      - args:
        - /nginx-ingress-controller
        - --watch-ingress-without-class=true
        - --configmap=ingress-nginx/nginx-configuration
        - --annotations-prefix=nginx.ingress.kubernetes.io
        - --profiling=false
        - --publish-service=ingress-nginx/ingress-nginx
        - --report-node-internal-ip-address
        - --update-status
        - --update-status-on-shutdown
        - --default-ssl-certificate=ingress-nginx/tls-secret
        - --disable-catch-all

• Current State of the controller:
  • kubectl describe ingressclasses

❯ kubectl describe ingressclasses
Name:         ingress-nginx
Labels:       app=nginx-ingress-controller
              app.kubernetes.io/component=controller
              app.kubernetes.io/instance=nginx-ingress-controller
              app.kubernetes.io/name=ingress-nginx
              app.kubernetes.io/part-of=ingress-nginx
              app.kubernetes.io/version=1.2.1
Annotations:  <none>
Controller:   k8s.io/ingress-nginx
Events:       <none>


**How to reproduce this issue**:

curl the nginx health check to show it gives a 200

deploy an ingress without a host and setup `nginx.ingress.kubernetes.io/rewrite-target: /$2`
verify you can hit the application ingress
curl the nginx health check and see a 404

**Anything else we need to know**:

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