Ingress规范在更新到v1后已更改。请尝试：

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - http:
      paths:
      - path: /nginx
        pathType: ImplementationSpecific
        backend:
          service:
            name: nginx
            port:
              number: 80

根据this documentation，您需要更改ServiceName和ServicePort。
每个HTTP规则都包含（...）一个路径列表（例如/testpath），每个路径都有一个关联的后端，后端定义为service.name和service.port.name或service.port.number。在负载均衡器将流量定向到引用的服务之前，主机和路径都必须与传入请求的内容匹配。
下面是您的yaml文件，其中包含更正：

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - http:
      paths:
      - path: /nginx
        backend:
          service:
            name: nginx
            port:
              number: 8080

ServiceName和ServicePort没有像v1中那样的关键字可用。

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - http:
      paths:
      - path: /nginx
        backend:
          service:
            name: nginx
            port:
              number: 8080

服务名称和服务端口语法不正确。请按照以下示例操作

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: minimal-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx-example
  rules:
  - http:
      paths:
      - path: /testpath
        pathType: Prefix
        backend:
          service:
            name: test
            port:
              number: 80

api版本：networking.k8s.io/v1类型：入口元数据：name：nginx-ingress注解：nginx.ingress.kubernetes.io/rewrite-target:：rules：

• HTTP：路径：
• path：/nginx pathType：特定于实现的后端：服务：名称：nginx端口：数量：80