Strip part of URI

[rsemlal.tas]

Since it took me a while to figure things out, I thought sharing my solution might help

For the record, I had the same problem, I end up using:

• The plugin GitHub - alexashley/kong-plugin-path-prefix: A Kong plugin to rewrite the upstream request path to strip the path prefix
• The post-function plugin to set the X-Forwarded-Prefix properly

Full example with Kong Ingress Controller

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: strip-demo-2-path-prefix
config:
  path_prefix: "/foo/"
plugin: path-prefix
---
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: set-forwarded-header
plugin: post-function
config:
  access:
    - |
      ngx.var.upstream_x_forwarded_prefix='/foo'
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: demo-2
  annotations:
    konghq.com/strip-path: "false"
    konghq.com/plugins: strip-demo-2-path-prefix,set-forwarded-header
spec:
  ingressClassName: kong
  rules:
  - http:
      paths:
      - backend:
          service:
            name: echo
            port:
              number: 80
        path: /foo/bar
        pathType: ImplementationSpecific

With this solution:

• Requests to /foo/bar are captured by Kong
• They are routed to the upstream service to the path /bar
• The forwarded request has the header X-Forwarded-Prefix: /foo (which makes the upstream service able to find out what its external url is)