kubernetes nginx ingress error with configuration-snippet

Question

I have following ingress.yaml file

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
    name: nginx-configuration-snippet
    annotations:
        nginx.ingress.kubernetes.io/rewrite-target: /$2
        nginx.ingress.kubernetes.io/configuration-snippet: |
          location /base/path/v1/api/update {
              deny all;
              return 404;
            }
spec:
  rules:
    - http:
        paths:
          - path: /base/path(/|$)(.*)
            backend:
              serviceName: myApi
              servicePort: 8080

But when I send a request to https:///base/path/v1/api/update it succeeds and I got following error in nginx ingress controller

Error: exit status 1
2020/08/06 18:35:07 [emerg] 1734#1734: location "/base/path/v1/api/update" is outside location "^/base/path(/|$)(.*)" in /tmp/nginx-cfg008325631:2445
nginx: [emerg] location "/base/path/v1/api/update" is outside location "^/base/path(/|$)(.*)" in /tmp/nginx-cfg008325631:2445
nginx: configuration file /tmp/nginx-cfg008325631 test failed

Can somebody help?

Answer 1

The configuration-snippet is to add configs to locations.

If you want to add a custom location to the server context, you should use the server-snippet instead:

Using the annotation nginx.ingress.kubernetes.io/server-snippet it is possible to add custom configuration in the server configuration block.

You also need to use some modifiers and regex to make it work (~* and ^).

The following config should work:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
    name: nginx-configuration-snippet
    annotations:
        nginx.ingress.kubernetes.io/rewrite-target: /$2
        nginx.ingress.kubernetes.io/server-snippet: |
          location ~* "^/base/path/v1/api/update" {
              deny all;
              return 403;
            }
spec:
  rules:
    - http:
        paths:
          - path: /base/path(/|$)(.*)
            backend:
              serviceName: myApi
              servicePort: 8080

The final nginx.config should end like this:

$ kubectl exec -n kube-system nginx-ingress-controller-6fc5bcc8c9-chkxf -- cat /etc/nginx/nginx.conf

[...]

location ~* "^/base/path/v1/api/update" {
            deny all;
            return 403;
        }
        
location ~* "^/base/path(/|$)(.*)" {
[...]           
}