getting 503 service not available after doing configuration

Question

I have application "test.abc.com". I want to transfer request between different service.

Example or Expected output

• when user hit test.abc.com --> it will go to abc-demo-frontend-external service
• when user hit test.abc.com/main.js or test.abc.com/main.css or any .css/ .js files --> it will go to abc-demo-frontend service

I have added below configuration

apiVersion: networking.k8s.io/v1
        kind: Ingress
        metadata:
          name: test-demo-frontend-ingress
          annotations:
            kubernetes.io/ingress.class: nginx
            nginx.ingress.kubernetes.io/ssl-redirect: 'false'
            nginx.ingress.kubernetes.io/use-regex: "true"
        spec:
          rules:
            - host: "test.abc.com"
              http:
                paths:
                  - path: /[^\/#?]+\.(?:css|js)(?![^\/?#])
                    pathType: ImplementationSpecific
                    backend:
                      service:
                        name: abc-demo-frontend
                        port:
                          number: 80
                  - path: /
                    pathType: ImplementationSpecific
                    backend:
                      service:
                        name: abc-demo-frontend-external
                        port:
                          number: 80

after adding [^\/#?]+\.(?:css|js)(?![^\/?#]) path I am getting 503 why ?

when I add below path I am getting 503 why ?

- path: /[^\/#?]+\.(?:css|js)(?![^\/?#])
                        pathType: ImplementationSpecific
                        backend:
                          service:
                            name: abc-demo-frontend
                            port:
                              number: 80

Answer 1

The Regex used in the spec.rules.http.paths.path for K8s ingress-nginx should be comply with RE2 engine syntax; see here. Seems the Regex that you are using does not comply with the RE2 engine syntax. Check it with the supported syntax in https://github.com/google/re2/wiki/Syntax.

Because of this, your ingress-nginx pods should not be ready. Pods are not being ready should be the reason to get 503 - service unavailable issue. Try updating the Regex according to the RE2 syntax and then check it again.