HTTP Request Header Manipulate
The HTTP header manipulation feature allows you to fine-tune incoming and outgoing request and response headers.
In Gateway API, the HTTPRoute resource utilities two HTTPHeaderFilter filter for request and response header manipulation.
The both filters supports add, set and remove operation. The combination of them is also available.
This document will introduce the HTTP request header manipulation function of FSM Gateway. The introduction of HTTP response header manipulation is located in doc HTTP Response Header Manipulate.
Prerequisites
- Kubernetes cluster version v1.21.0 or higher.
- kubectl CLI
- FSM Gateway installed via guide doc.
Demonstration
We will follow the sample in HTTP Routing.
In backend service, there is a path /headers which will respond all request headers.
curl -H 'host:foo.example.com' http://$GATEWAY_IP:8000/headers
{
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Host": "10.42.0.15:80",
"User-Agent": "curl/8.1.2"
}
}
Add HTTP Request header
With header adding feature, let’s try to add a new header to request by add HTTPHeaderFilter filter.
Modifying the HTTPRoute http-route-foo and add RequestHeaderModifier filter.
kubectl apply -n httpbin -f - <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
name: http-route-foo
spec:
parentRefs:
- name: simple-fsm-gateway
port: 8000
hostnames:
- foo.example.com
rules:
- matches:
- path:
type: PathPrefix
value: /
backendRefs:
- name: httpbin
port: 8080
filters:
- type: RequestHeaderModifier
requestHeaderModifier:
add:
- name: "header-2-add"
value: "foo"
EOF
Now request the path /headers again and you will get the new header injected by gateway.
Thought HTTP header name is case insensitive but it will be converted to capital mode.
curl -H 'host:foo.example.com' http://$GATEWAY_IP:8000/headers
{
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Header-2-Add": "foo",
"Host": "10.42.0.15:80",
"User-Agent": "curl/8.1.2"
}
}
Set HTTP Request header
set operation is used to update the value of specified header. If the header not exist, it will do as add operation.
Let’s update the HTTPRoute resource again and set two headers with new value. One does not exist and another does.
kubectl apply -n httpbin -f - <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
name: http-route-foo
spec:
parentRefs:
- name: simple-fsm-gateway
port: 8000
hostnames:
- foo.example.com
rules:
- matches:
- path:
type: PathPrefix
value: /
backendRefs:
- name: httpbin
port: 8080
filters:
- type: RequestHeaderModifier
requestHeaderModifier:
set:
- name: "header-2-set"
value: "foo"
- name: "user-agent"
value: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Safari/605.1.15"
EOF
In the response, we can get the two headers updated.
curl -H 'host:foo.example.com' http://$GATEWAY_IP:8000/headers
{
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Header-2-Set": "foo",
"Host": "10.42.0.15:80",
"User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Safari/605.1.15"
}
}
Remove HTTP Request header
The last operation is remove, which can remove the header of client sending.
Let’s update the HTTPRoute resource to remove user-agent header directly to hide client type from backend service.
kubectl apply -n httpbin -f - <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
name: http-route-foo
spec:
parentRefs:
- name: simple-fsm-gateway
port: 8000
hostnames:
- foo.example.com
rules:
- matches:
- path:
type: PathPrefix
value: /
backendRefs:
- name: httpbin
port: 8080
filters:
- type: RequestHeaderModifier
requestHeaderModifier:
remove:
- "user-agent"
EOF
With resource udpated, the user agent is invisible on backend service side.
curl -H 'host:foo.example.com' http://$GATEWAY_IP:8000/headers
{
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Host": "10.42.0.15:80"
}
}
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