HTTP Redirect
Request redirection is a common network application function that allows the server to tell the client: “The resource you requested has been moved to another location, please go to the new location to obtain it.”
The HTTPRoute resource utilizes HTTPRequestRedirectFilter to redirect client to the specified new location.
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 our backend server, there are two paths /headers and /get. The previous one responds all request headers as body, and the latter one responds more information of client than /headers.
To facilitate testing, it’s better to add records to local hosts.
echo $GATEWAY_IP foo.example.com bar.example.com >> /etc/hosts
-bash: /etc/hosts: Permission denied
curl foo.example.com/headers
{
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Host": "foo.example.com",
"User-Agent": "curl/7.68.0"
}
}
curl bar.example.com/get
{
"args": {},
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Host": "bar.example.com",
"User-Agent": "curl/7.68.0"
},
"origin": "10.42.0.87",
"url": "http://bar.example.com/get"
}
Host Name Redirect
The HTTP status code 3XX are used to redirect client to another address. We can redirect all requests to foo.example.com to bar.example.com by responding 301 status and new hostname.
apiVersion: gateway.networking.k8s.io/v1beta1
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: /
filters:
- type: RequestRedirect
requestRedirect:
hostname: bar.example.com
port: 8000
statusCode: 301
backendRefs:
- name: httpbin
port: 8080
Now, it will return the 301 code and bar.example.com:8000 when requesting foo.example.com.
curl -i http://foo.example.com:8000/get
HTTP/1.1 301 Moved Permanently
Location: http://bar.example.com:8000/get
content-length: 0
connection: keep-alive
By default, curl does not follow location redirecting unless enable it by assign opiton -L.
curl -L http://foo.example.com:8000/get
{
"args": {},
"headers": {
"Accept": "*/*",
"Connection": "keep-alive",
"Host": "bar.example.com:8000",
"User-Agent": "curl/7.68.0"
},
"origin": "10.42.0.161",
"url": "http://bar.example.com:8000/get"
}
Prefix Path Redirect
With path redirection, we can implement what we did with URL Rewriting: redirect the request to /status/{n} to /stream/{n}.
apiVersion: gateway.networking.k8s.io/v1beta1
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: /status
filters:
- type: RequestRedirect
requestRedirect:
path:
type: ReplacePrefixMatch
replacePrefixMatch: /stream
statusCode: 301
backendRefs:
- name: httpbin
port: 8080
- matches:
backendRefs:
- name: httpbin
port: 8080
After update rull, we will get.
curl -i http://foo.example.com:8000/status/204
HTTP/1.1 301 Moved Permanently
Location: http://foo.example.com:8000/stream/204
content-length: 0
connection: keep-alive
Full Path Redirect
We can also change full path during redirecting, such as redirect all /status/xxx to /status/200.
apiVersion: gateway.networking.k8s.io/v1beta1
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: /status
filters:
- type: RequestRedirect
requestRedirect:
path:
type: ReplaceFullPath
replaceFullPath: /status/200
statusCode: 301
backendRefs:
- name: httpbin
port: 8080
- matches:
backendRefs:
- name: httpbin
port: 8080
Now, the status of requests to /status/xxx will be redirected to /status/200.
curl -i http://foo.example.com:8000/status/204
HTTP/1.1 301 Moved Permanently
Location: http://foo.example.com:8000/status/200
content-length: 0
connection: keep-alive
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