docs/serving/samples/steren-function

Sample Function

A trivial function for HTTP events, which returns "Hello {name}", for a querystring parameter name.

This is based on the source code available from: github.com/steren/sample-function

Prerequisites

Install Knative Serving

Running

You can deploy this to Knative Serving from the root directory via:

# Replace the token string with a suitable registry
REPO="gcr.io/<your-project-here>"
perl -pi -e "s@DOCKER_REPO_OVERRIDE@$REPO@g" sample/steren-function/sample.yaml

# Create the Kubernetes resources
kubectl apply -f sample/templates/node-fn.yaml -f sample/steren-function/sample.yaml

Once deployed, you will see that it first builds:

$ kubectl get revision -o yaml
apiVersion: v1
items:
- apiVersion: serving.knative.dev/v1alpha1
  kind: Revision
  ...
  status:
    conditions:
    - reason: Building
      status: "False"
      type: BuildComplete
...

Once the BuildComplete status becomes True the resources will start getting created.

To access this service via curl, we first need to determine its ingress address:

$ watch kubectl get svc knative-ingressgateway -n istio-system
NAME                     TYPE           CLUSTER-IP     EXTERNAL-IP      PORT(S)                                      AGE
knative-ingressgateway   LoadBalancer   10.23.247.74   35.203.155.229   80:32380/TCP,443:32390/TCP,32400:32400/TCP   2d

Once the ADDRESS gets assigned to the cluster, you can run:

# Put the Host name into an environment variable.
export SERVICE_HOST=`kubectl get route steren-sample-fn -o jsonpath="{.status.domain}"`

# Put the ingress IP into an environment variable.
export SERVICE_IP=`kubectl get svc knative-ingressgateway -n istio-system -o jsonpath="{.status.loadBalancer.ingress[*].ip}"`

If your cluster is running outside a cloud provider (for example on Minikube), your services will never get an external IP address. In that case, use the istio hostIP and nodePort as the service IP:

export SERVICE_IP=$(kubectl get po -l knative=ingressgateway -n istio-system -o 'jsonpath={.items[0].status.hostIP}'):$(kubectl get svc knative-ingressgateway -n istio-system -o 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')

Now curl the service IP as if DNS were properly configured:

$ curl --header "Host:$SERVICE_HOST" http://${SERVICE_IP}/execute?name=${USER}
Hello mattmoor

Cleaning up

To clean up the sample service:

kubectl delete -f sample/templates/node-fn.yaml -f sample/steren-function/sample.yaml