HTTP URL Rewrite

HTTPURLRewriteFilter defines a filter that modifies a request during forwarding. At most one of these filters may be used on a Route rule. This MUST NOT be used on the same Route rule as a HTTPRequestRedirect filter.

Prerequisites

Follow the steps from the Quickstart Guide to install Envoy Gateway and the example manifest. Before proceeding, you should be able to query the example backend using HTTP.

Rewrite URL Prefix Path

You can configure to rewrite the prefix in the url like below. In this example, any curls to http://${GATEWAY_HOST}/get/xxx will be rewritten to http://${GATEWAY_HOST}/replace/xxx.

cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: http-filter-url-rewrite
spec:
  parentRefs:
    - name: eg
  hostnames:
    - path.rewrite.example
  rules:
    - matches:
      - path:
          value: "/get"
      filters:
      - type: URLRewrite
        urlRewrite:
          path:
            type: ReplacePrefixMatch
            replacePrefixMatch: /replace
      backendRefs:
      - name: backend
        port: 3000
EOF

The HTTPRoute status should indicate that it has been accepted and is bound to the example Gateway.

kubectl get httproute/http-filter-url-rewrite -o yaml

Get the Gateway’s address:

export GATEWAY_HOST=$(kubectl get gateway/eg -o jsonpath='{.status.addresses[0].value}')

Querying http://${GATEWAY_HOST}/get/origin/path should rewrite to http://${GATEWAY_HOST}/replace/origin/path.

$ curl -L -vvv --header "Host: path.rewrite.example" "http://${GATEWAY_HOST}/get/origin/path"
...
> GET /get/origin/path HTTP/1.1
> Host: path.rewrite.example
> User-Agent: curl/7.85.0
> Accept: */*
>

< HTTP/1.1 200 OK
< content-type: application/json
< x-content-type-options: nosniff
< date: Wed, 21 Dec 2022 11:03:28 GMT
< content-length: 503
< x-envoy-upstream-service-time: 0
< server: envoy
<
{
 "path": "/replace/origin/path",
 "host": "path.rewrite.example",
 "method": "GET",
 "proto": "HTTP/1.1",
 "headers": {
  "Accept": [
   "*/*"
  ],
  "User-Agent": [
   "curl/7.85.0"
  ],
  "X-Envoy-Expected-Rq-Timeout-Ms": [
   "15000"
  ],
  "X-Envoy-Original-Path": [
   "/get/origin/path"
  ],
  "X-Forwarded-Proto": [
   "http"
  ],
  "X-Request-Id": [
   "fd84b842-9937-4fb5-83c7-61470d854b90"
  ]
 },
 "namespace": "default",
 "ingress": "",
 "service": "",
 "pod": "backend-6fdd4b9bd8-8vlc5"
...

You can see that the X-Envoy-Original-Path is /get/origin/path, but the actual path is /replace/origin/path.

Rewrite URL Full Path

You can configure to rewrite the fullpath in the url like below. In this example, any request sent to http://${GATEWAY_HOST}/get/origin/path/xxxx will be rewritten to http://${GATEWAY_HOST}/force/replace/fullpath.

cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: http-filter-url-rewrite
spec:
  parentRefs:
    - name: eg
  hostnames:
    - path.rewrite.example
  rules:
    - matches:
      - path:
          type: PathPrefix
          value: "/get/origin/path"
      filters:
      - type: URLRewrite
        urlRewrite:
          path:
            type: ReplaceFullPath
            replaceFullPath: /force/replace/fullpath
      backendRefs:
      - name: backend
        port: 3000
EOF

The HTTPRoute status should indicate that it has been accepted and is bound to the example Gateway.

kubectl get httproute/http-filter-url-rewrite -o yaml

Querying http://${GATEWAY_HOST}/get/origin/path/extra should rewrite the request to http://${GATEWAY_HOST}/force/replace/fullpath.

$ curl -L -vvv --header "Host: path.rewrite.example" "http://${GATEWAY_HOST}/get/origin/path/extra"
...
> GET /get/origin/path/extra HTTP/1.1
> Host: path.rewrite.example
> User-Agent: curl/7.85.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< content-type: application/json
< x-content-type-options: nosniff
< date: Wed, 21 Dec 2022 11:09:31 GMT
< content-length: 512
< x-envoy-upstream-service-time: 0
< server: envoy
<
{
 "path": "/force/replace/fullpath",
 "host": "path.rewrite.example",
 "method": "GET",
 "proto": "HTTP/1.1",
 "headers": {
  "Accept": [
   "*/*"
  ],
  "User-Agent": [
   "curl/7.85.0"
  ],
  "X-Envoy-Expected-Rq-Timeout-Ms": [
   "15000"
  ],
  "X-Envoy-Original-Path": [
   "/get/origin/path/extra"
  ],
  "X-Forwarded-Proto": [
   "http"
  ],
  "X-Request-Id": [
   "8ab774d6-9ffa-4faa-abbb-f45b0db00895"
  ]
 },
 "namespace": "default",
 "ingress": "",
 "service": "",
 "pod": "backend-6fdd4b9bd8-8vlc5"
...

You can see that the X-Envoy-Original-Path is /get/origin/path/extra, but the actual path is /force/replace/fullpath.

Rewrite Host Name

You can configure to rewrite the hostname like below. In this example, any requests sent to http://${GATEWAY_HOST}/get with --header "Host: path.rewrite.example" will rewrite host into envoygateway.io.

cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: http-filter-url-rewrite
spec:
  parentRefs:
    - name: eg
  hostnames:
    - path.rewrite.example
  rules:
    - matches:
      - path:
          type: PathPrefix
          value: "/get"
      filters:
      - type: URLRewrite
        urlRewrite:
          hostname: "envoygateway.io"
      backendRefs:
      - name: backend
        port: 3000
EOF

The HTTPRoute status should indicate that it has been accepted and is bound to the example Gateway.

kubectl get httproute/http-filter-url-rewrite -o yaml

Querying http://${GATEWAY_HOST}/get with --header "Host: path.rewrite.example" will rewrite host into envoygateway.io.

$ curl -L -vvv --header "Host: path.rewrite.example" "http://${GATEWAY_HOST}/get"
...
> GET /get HTTP/1.1
> Host: path.rewrite.example
> User-Agent: curl/7.85.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< content-type: application/json
< x-content-type-options: nosniff
< date: Wed, 21 Dec 2022 11:15:15 GMT
< content-length: 481
< x-envoy-upstream-service-time: 0
< server: envoy
<
{
 "path": "/get",
 "host": "envoygateway.io",
 "method": "GET",
 "proto": "HTTP/1.1",
 "headers": {
  "Accept": [
   "*/*"
  ],
  "User-Agent": [
   "curl/7.85.0"
  ],
  "X-Envoy-Expected-Rq-Timeout-Ms": [
   "15000"
  ],
  "X-Forwarded-Host": [
   "path.rewrite.example"
  ],
  "X-Forwarded-Proto": [
   "http"
  ],
  "X-Request-Id": [
   "39aa447c-97b9-45a3-a675-9fb266ab1af0"
  ]
 },
 "namespace": "default",
 "ingress": "",
 "service": "",
 "pod": "backend-6fdd4b9bd8-8vlc5"
...

You can see that the X-Forwarded-Host is path.rewrite.example, but the actual host is envoygateway.io.


Last modified May 25, 2024: fix api wording (#3467) (5bc5e0f)