Adding support forward all headrs from downstream to upstream

[alzaicko]

Is your feature request related to a problem? Please describe.
I need to pass custom values ​​in the Host header to upstream, at the moment I can’t override the Host header in any way.

Describe the solution you'd like
Make settings in the configuration so that for the Host header, which will be sent to upstream, the value will be taken from the transmitted X-Forwarded-Host header

Describe alternatives you've considered
For example, how it is implemented here:

use-forwarded-headers - https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#use-forwarded-headers
If true, NGINX passes the incoming X-Forwarded-* headers to upstreams. Use this option when NGINX is behind another L7 proxy / load balancer that is setting these headers.

If false, NGINX ignores incoming X-Forwarded-* headers, filling them with the request information it sees. Use this option if NGINX is exposed directly to the internet, or it's behind a L3/packet-based load balancer that doesn't alter the source IP in the packets.

[github-actions]

Hi @alzaicko thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!

[j1m-ryan]

Hi @alzaicko. Yes this is possible.
This is easiest using the VirtualServer resource.

I deployed a simple VirtualServer, similar to the example in here.

The main difference is using action.proxy instead of action.pass. This allows defining a list of headers to set in the requestHeaders.set. Below I set X-Forwarded-Host to example2.com, with the VirtualServer itself listening on cafe.example.com.

apiVersion: k8s.nginx.org/v1
kind: VirtualServer
metadata:
  name: cafe
spec:
  host: cafe.example.com
  tls:
    secret: cafe-secret
  upstreams:
  - name: coffee
    service: coffee-svc
    port: 80
  routes:
  - path: /coffee
    action:
      proxy:
        upstream: coffee
        requestHeaders:
          set:
            - name: X-Forwarded-Host
              value: example2.com

In the deployment that the coffee-svc references, I deployed the image mendhak/http-https-echo which returns json of all the headers sent to it.

When I curl cafe.example.com/coffee I get this response.

{
  "path": "/coffee",
  "headers": {
    "connection": "close",
    "x-real-ip": "10.244.0.1",
    "x-forwarded-for": "10.244.0.1",
    "x-forwarded-port": "80",
    "x-forwarded-proto": "http",
    "x-forwarded-host": "example2.com",
    "host": "cafe.example.com",
    "user-agent": "curl/8.6.0",
    "accept": "*/*"
  },
  "method": "GET",
  "body": "",
  "fresh": false,
  "hostname": "example2.com",
  "ip": "10.244.0.1",
  "ips": [
    "10.244.0.1"
  ],
  "protocol": "http",
  "query": {},
  "subdomains": [],
  "xhr": false,
  "os": {
    "hostname": "coffee-c96565fcd-rr8vp"
  },
  "connection": {}
}

Here you can see "x-forwarded-host": "example2.com",

Edit:
Just to add also, you see the docs on this here