HTTP URL Rewrite
5 minute read
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 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/v1
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
Save and apply the following resource to your cluster:
---
apiVersion: gateway.networking.k8s.io/v1
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
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://${GATEWAY_HOST}/force/replace/fullpath.
cat <<EOF | kubectl apply -f -
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
name: http-filter-url-rewrite
spec:
parentRefs:
- name: eg
hostnames:
- path.rewrite.example
rules:
- matches:
- path:
type: PathPrefix
value: "/get/origin/path"
filters:
- type: URLRewrite
urlRewrite:
path:
type: ReplaceFullPath
replaceFullPath: /force/replace/fullpath
backendRefs:
- name: backend
port: 3000
EOF
Save and apply the following resource to your cluster:
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
name: http-filter-url-rewrite
spec:
parentRefs:
- name: eg
hostnames:
- path.rewrite.example
rules:
- matches:
- path:
type: PathPrefix
value: "/get/origin/path"
filters:
- type: URLRewrite
urlRewrite:
path:
type: ReplaceFullPath
replaceFullPath: /force/replace/fullpath
backendRefs:
- name: backend
port: 3000
The HTTPRoute status should indicate that it has been accepted and is bound to the example Gateway.
kubectl get httproute/http-filter-url-rewrite -o yaml
Querying http://${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/v1
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
Save and apply the following resource to your cluster:
---
apiVersion: gateway.networking.k8s.io/v1
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
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.
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