Remove the Prefix from an Route in Istio
this is common where the Istio will have some part of the route to identify which service, and will want to remove the identifier.
We look at how we can rewrite the URL routing to downstream services.
This is a increasingly common pattern
[client] -> {api.com/service/proxy} -|
|
-----------------------------------
|
|-----> [Gateway] -> {/proxy} ----|
|
-----------------------------------
|
|-----> [service]
the client calls the ingress, where the {service} part of the request is used to identify the downstream service, however the service only needs the /{proxy}
High-Level steps
- setup a virtual service with prefixes and a re-write
virtual service setup
In this VirtualService, below, we setup a weather service, however we remove the weather from the url, effively allowing for the server to deal with the rest of the URI
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
namespace: weather
name: weather
spec:
hosts:
- "*"
gateways:
- istio-system/awesome-io-gateway
http:
- match:
- uri:
prefix: "/weather/"
- uri:
prefix: "/weather"
rewrite:
uri: "/"
route:
- destination:
port:
number: 80
host: weather-svc
note that the prefix is done twice, this is a work-around (https://github.com/istio/istio/issues/8076)
the example of this when it is run would be the following
Client calls:
curl "http://awesome.io:31380/weather/v1/weatherforecast"
Istio calls the service with
"http://weather-svc/v1/weatherforecast"
the weather-svc is effectively the kuberneties service entry which resides in the same namespace as the VirtualService, note that it does not have to match the prefix.
just for reference:
apiVersion: v1
kind: Service
metadata:
namespace: weather
name: weather-svc
labels:
app: weather-svc
spec:
ports:
- name: http
port: 80
targetPort: 80
selector:
app: weather-svc
