Prevent a VirtualServerRoute from being used multiple times in a Virtual Server to avoid reload failure #6611
Description
Is your feature request related to a problem? Please describe.
Currently, NIC does not prevent the same VSR being used twice in the same VS, allowing specs that results in generating the same location block /coffee and the same upstream twice, which causes NGINX to trigger a "duplicate upstream" error upon reload:
Consider this VSR:
apiVersion: k8s.nginx.org/v1
kind: VirtualServerRoute
metadata:
name: coffee
namespace: coffee
spec:
host: cafe.example.com
upstreams:
- name: coffee
service: coffee-svc
port: 80
subroutes:
- path: /coffee
action:
pass: coffee
Currently, the following VS spec is allowed.
apiVersion: k8s.nginx.org/v1
kind: VirtualServer
metadata:
name: cafe
namespace: cafe
spec:
host: cafe.example.com
tls:
secret: cafe-secret
routes:
- path: /coffee
route: coffee/coffee
- path: /
route: coffee/coffee
which would result in the location block with the same path and upstreams with the same name vs_cafe_cafe_vsr_coffee_coffee_coffee generated in the NGINX config, resulting in the following reloading error
Warning AddedOrUpdatedWithError 11s nginx-ingress-controller Configuration for cafe/cafe was added or updated ; but was not applied: error when updating config from ConfigMap: nginx reload failed: command /usr/sbin/nginx -s reload -e stderr stdout: ""
stderr: "2024/10/08 08:30:19 [emerg] 42#42: duplicate upstream \"vs_cafe_cafe_vsr_coffee_coffee_coffee\" in /etc/nginx/conf.d/vs_cafe_cafe.conf:10\n"
Describe the solution you'd like
Disallow a VSR being used multiple times to prevent reload failure
Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
Additional context
This config error in obvious in the current specification where the VSRs is explicitly referenced in the VS spec. However, it might become less apparent in the future work #5293, where VSRs are associated with a VS through different methods.