feat: add health probes to node & go services (#174)

Until the next release of Quarkus in November, we'll need to have some special
checks so that we don't add these probes to Quarkus based functions. In the
meantime, we can at least set the liveness and readiness endpoints on the
Node.js/Go functions to /health/liveness and /health/readiness respectively.

Fixes: #169

Signed-off-by: Lance Ball <lball@redhat.com>

Author: lance

knative/deployer.go

@@ -57,7 +57,7 @@ func (d *Deployer) Deploy(f faas.Function) (err error) {
 			if d.Verbose {
 				fmt.Printf("Creating Knative Service: %v\n", serviceName)
 			}
-			err := client.CreateService(generateNewService(serviceName, f.Image))
+			err := client.CreateService(generateNewService(serviceName, f.Image, f.Runtime != "quarkus"))
 			if err != nil {
 				err = fmt.Errorf("knative deployer failed to deploy the service: %v", err)
 				return err
@@ -99,7 +99,17 @@ func (d *Deployer) Deploy(f faas.Function) (err error) {
 	return nil
 }
 
-func generateNewService(name, image string) *servingv1.Service {
+func probeFor(url string) *corev1.Probe {
+	return &corev1.Probe{
+		Handler: corev1.Handler{
+			HTTPGet: &corev1.HTTPGetAction{
+				Path: url,
+			},
+		},
+	}
+}
+
+func generateNewService(name, image string, healthChecks bool) *servingv1.Service {
 	containers := []corev1.Container{
 		{
 			Image: image,
@@ -109,6 +119,11 @@ func generateNewService(name, image string) *servingv1.Service {
 		},
 	}
 
+	if healthChecks {
+		containers[0].LivenessProbe = probeFor("/health/liveness")
+		containers[0].ReadinessProbe = probeFor("/health/readiness")
+	}
+
 	return &v1.Service{
 		ObjectMeta: metav1.ObjectMeta{
 			Name: name,