We use analytics and cookies to understand site traffic. Information about your use of our site is shared with Google for that purpose. Learn more.
Routing across multiple Knative services - Go
This example shows how to map multiple Knative services to different paths under a single domain name using the Istio VirtualService concept. Istio is a general-purpose reverse proxy, therefore these directions can also be used to configure routing based on other request data such as headers, or even to map Knative and external resources under the same domain name.
In this sample, we set up two web services: Search
service and Login
service, which simply read in an env variable SERVICE_NAME
and prints
"${SERVICE_NAME} is called"
. We’ll then create a VirtualService with host
example.com
, and define routing rules in the VirtualService so that
example.com/search
maps to the Search service, and example.com/login
maps to
the Login service.
Prerequisites
- A Kubernetes cluster with Knative Serving installed.
- Install Docker.
- Acquire a domain name.
- In this example, we use
example.com
. If you don’t have a domain name, you can modify your hosts file (on Mac or Linux) to mapexample.com
to your cluster’s ingress IP. - If you have configured a custom domain for your Knative installation, we will refer to it as <YOUR_DOMAIN_NAME> in the rest of this document
- In this example, we use
- Check out the code:
go get -d github.com/knative/docs/docs/serving/samples/knative-routing-go
Setup
To check the domain name, run the following command:
kubectl get cm -n knative-serving config-domain -o yaml
Then, check the value for data
. The domain name should be in the format of
<YOUR_DOMAIN_NAME>: ""
, if it is available.
Build the application container and publish it to a container registry:
- Move into the sample directory:
cd $GOPATH/src/github.com/knative/docs
- Set your preferred container registry:
If you use Google Container Registry (GCR), you will need to enable the GCR API in your GCP project.
export REPO="gcr.io/<YOUR_PROJECT_ID>"
If you use Docker Hub as your docker image registry, replace
export REPO="docker.io/<username>"
- Use Docker to build your application container:
docker build \
--tag "${REPO}/knative-routing-go" \
--file=docs/serving/samples/knative-routing-go/Dockerfile .
- Push your container to a container registry:
docker push "${REPO}/knative-routing-go"
-
Replace the image reference path with our published image path in the configuration file
docs/serving/samples/knative-routing-go/sample.yaml
:- Manually replace:
image: github.com/knative/docs/docs/serving/samples/knative-routing-go
withimage: ${REPO}/knative-routing-go
If you manually changed the .yaml file, you must replace ${REPO} with the correct path on your local machine.
Or
- Run this command:
perl -pi -e "s@github.com/knative/docs/docs/serving/samples@${REPO}@g" docs/serving/samples/knative-routing-go/sample.yaml
- Manually replace:
Deploy the Service
Deploy the Knative Serving sample:
kubectl apply --filename docs/serving/samples/knative-routing-go/sample.yaml
Exploring the Routes
A shared Gateway knative-ingress-gateway
is used within Knative service mesh
for serving all incoming traffic. You can inspect it and its corresponding
Kubernetes service with:
- Check the shared Gateway:
kubectl get Gateway --namespace knative-serving --output yaml
- Check the corresponding Kubernetes service for the shared Gateway:
INGRESSGATEWAY=istio-ingressgateway
kubectl get svc $INGRESSGATEWAY --namespace istio-system --output yaml
- Inspect the deployed Knative services with:
kubectl get ksvc
You should see 2 Knative services: search-service
and login-service
.
Access the Services
- Find the shared Gateway IP and export as an environment variable:
INGRESSGATEWAY=istio-ingressgateway
export GATEWAY_IP=`kubectl get svc $INGRESSGATEWAY --namespace istio-system \
--output jsonpath="{.status.loadBalancer.ingress[*]['ip']}"`
- Find the
Search
service URL with:
# kubectl get route search-service --output=custom-columns=NAME:.metadata.name,URL:.status.url
NAME URL
search-service http://search-service.default.example.com
- Make a curl request to the service:
curl http://${GATEWAY_IP} --header "Host:search-service.default.example.com"
You should see: Search Service is called !
- Similarly, you can also directly access “Login” service with:
curl http://${GATEWAY_IP} --header "Host:login-service.default.example.com"
You should see: Login Service is called !
Apply Custom Routing Rule
- Apply the custom routing rules defined in
routing.yaml
file with:
kubectl apply --filename docs/serving/samples/knative-routing-go/routing.yaml
If you have configured a custom domain name for your service, please replace all
mentions of “example.com” in routing.yaml
with “<YOUR_DOMAIN_NAME>” for
spec.hosts and spec.http.rewrite.authority.
In addition, you need to verify how your domain template is defined. By default, we use the format of {{.Name}}.{{.Namespace}}, like search-service.default and login-service.default. However, some Knative environments may use other format like {{.Name}}-{{.Namespace}}. You can find out the format by running the command:
kubectl get cm -n knative-serving config-network -o yaml
Then look for the value for domainTemplate
. If it is
{{.Name}}-{{.Namespace}}.{{.Domain}}
, you need to change
search-service.default
into search-service-default
and
login-service.default
into login-service-default
as well in routing.yaml
.
- The
routing.yaml
file will generate a new VirtualServiceentry-route
for domainexample.com
or your own domain name. View the VirtualService:
kubectl get VirtualService entry-route --output yaml
-
Send a request to the
Search
service and theLogin
service by using corresponding URIs. You should get the same results as directly accessing these services. Get the ingress IP:INGRESSGATEWAY=istio-ingressgateway export GATEWAY_IP=`kubectl get svc $INGRESSGATEWAY --namespace istio-system \ --output jsonpath="{.status.loadBalancer.ingress[*]['ip']}"`
-
Send a request to the Search service:
curl http://${GATEWAY_IP}/search --header "Host: example.com"
or
curl http://${GATEWAY_IP}/search --header "Host: <YOUR_DOMAIN_NAME>"
for the case using your own domain.
-
Send a request to the Login service:
curl http://${GATEWAY_IP}/login --header "Host: example.com"
or
curl http://${GATEWAY_IP}/login --header "Host: <YOUR_DOMAIN_NAME>"
for the case using your own domain.
How It Works
When an external request with host example.com
or your own domain name reaches
knative-ingress-gateway
Gateway, the entry-route
VirtualService will check
if it has /search
or /login
URI. If the URI matches, then the host of
request will be rewritten into the host of Search
service or Login
service
correspondingly. This resets the final destination of the request. The request
with updated host will be forwarded to knative-ingress-gateway
Gateway again.
The Gateway proxy checks the updated host, and forwards it to Search
or
Login
service according to its host setting.
Clean Up
To clean up the sample resources:
kubectl delete --filename docs/serving/samples/knative-routing-go/sample.yaml
kubectl delete --filename docs/serving/samples/knative-routing-go/routing.yaml
Feedback
Was this page helpful?
Glad to hear it! Please tell us how we can improve.
Sorry to hear that. Please tell us how we can improve.