Service annotation reconciler (#277)

* various changes

Signed-off-by: Jasmin Gacic <jasmin.gacic@gmail.com>

* add upstream to x-kusk if not present

Signed-off-by: Jasmin Gacic <jasmin.gacic@gmail.com>

* removed some leftovers

Signed-off-by: Jasmin Gacic <jasmin.gacic@gmail.com>

* removed some leftovers

Signed-off-by: Jasmin Gacic <jasmin.gacic@gmail.com>

* addressing PR remarks

Signed-off-by: Jasmin Gacic <jasmin.gacic@gmail.com>

* parse url before making http request to fetch openapi spec. Remove else clauses in favour of guard clauses

* doc for API autopilot

Signed-off-by: Jasmin Gacic <jasmin.gacic@gmail.com>

* Update docs/api_autopilot.md

Co-authored-by: Kyle Hodgetts <kyle@kubeshop.io>

* Update docs/api_autopilot.md

Co-authored-by: Kyle Hodgetts <kyle@kubeshop.io>

* Update docs/api_autopilot.md

Co-authored-by: Kyle Hodgetts <kyle@kubeshop.io>

* Update docs/api_autopilot.md

Co-authored-by: Kyle Hodgetts <kyle@kubeshop.io>

Co-authored-by: Kyle Hodgetts <kyle@kubeshop.io>

cmd/manager/main.go

@@ -281,6 +281,16 @@ func main() {
 		controllerConfigManager.WatchSecrets(ctx.Done())
 	}()
 
+	if err = (&controllers.ServiceReconciler{
+		Client: mgr.GetClient(),
+		Scheme: mgr.GetScheme(),
+	}).SetupWithManager(mgr); err != nil {
+		setupLog.
+			WithValues("controller", "ServiceAnnotationReconciler").
+			Error(err, "Unable to create controller")
+		os.Exit(1)
+	}
+
 	// EnvoyFleet obj controller
 	if err = (&controllers.EnvoyFleetReconciler{
 		Client:        mgr.GetClient(),

docs/api_autopilot.md

@@ -0,0 +1,56 @@
+# API autopilot
+
+Kusk gateway supports API auto deployment. 
+
+Any REST API will typically consist of a Kubernetes pod(s) that is running the server and a Kubernetes service pointed to it.
+
+## It just works
+To expose a pre-existing REST API in the cluster, you would just have to execute this:
+
+```sh
+kubectl apply -f svc.yaml
+```
+Or edit an existing Kubernetes service to add the annotation `kusk-gateway/openapi-url` with a URL to the location of your OpenAPI
+
+## Under the hood
+
+Let's explain what is going on.
+
+We added a convenience method that will allow users to easily expose their REST API through Kusk gateway by using the `kusk-gateway/openapi-url` annotation, and here is how.
+
+Assuming that the user has already set up a pod that is running REST API server code and the pod name is `todo-backend`:
+
+```yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: todo-backend
+  annotations:
+    kusk-gateway/openapi-url: https://gist.githubusercontent.com/jasmingacic/082849b29d0e06e5f018a66f4cd49ec3/raw/e91c94cc82e7591031399e0d8c563d28a62de460/openapi.yaml 
+    #NOTE: we need a sleeker URL for this
+spec:
+  type: ClusterIP
+  selector:
+    app: todo-backend # aforementioned pod name
+  ports:
+    - port: 3000
+      targetPort: http
+```
+
+Once the service is deployed to a cluster Kusk gateway will pick it up and create an API resource.
+Annotation `kusk-gateway/openapi-url` contains URL to OpenAPI spec for the user. Provided API may or may not contain `x-kusk` [extension](extension.md) so the reconciler will check if `x-kusk` extension is present and:
+   * if not present controller will add it and point upstream to the newly created service 
+```yaml
+x-kusk:
+    upstream:
+        name: todo-backend
+        namespace: default
+```
+  * or if the extension is present it will check if it contains `upstream` property configured. If not it will add it to the extension otherwise it will take OpenAPI definition as is and create API resource. 
+
+
+Upcoming features:
+- Refresh interval
+- Versioning
+- ...
+

go.mod

@@ -87,7 +87,7 @@ require (
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 	k8s.io/apiextensions-apiserver v0.23.0 // indirect
 	k8s.io/component-base v0.23.0 // indirect
 	k8s.io/klog/v2 v2.30.0 // indirect

internal/controllers/service_controller.go

@@ -0,0 +1,154 @@
+/*
+Copyright 2022.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package controllers
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	gateway "github.com/kubeshop/kusk-gateway/api/v1alpha1"
+
+	"gopkg.in/yaml.v3"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/runtime"
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/log"
+)
+
+// ServiceReconciler reconciles a Pod object
+type ServiceReconciler struct {
+	client.Client
+	Scheme *runtime.Scheme
+}
+
+//+kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;watch;create;update;patch;delete
+//+kubebuilder:rbac:groups=core,resources=pods/status,verbs=get;update;patch
+//+kubebuilder:rbac:groups=core,resources=pods/finalizers,verbs=update
+func (r *ServiceReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
+	l := log.FromContext(ctx).WithName("service-reconciler")
+
+	l.Info("Reconciling changed Service resource", "changed", req.NamespacedName)
+
+	svc := &corev1.Service{}
+	if err := r.Client.Get(ctx, client.ObjectKey{Namespace: req.Namespace, Name: req.Name}, svc); err != nil {
+		if errors.IsNotFound(err) {
+			return ctrl.Result{}, nil
+		}
+		return ctrl.Result{}, err
+	}
+
+	val, ok := svc.Annotations["kusk-gateway/openapi-url"]
+	if !ok {
+		return ctrl.Result{}, nil
+	}
+
+	l.Info(`Detected "kusk-gateway/openapi-url" annotation`, "found", val)
+
+	openapi, err := getOpenAPIfromURL(svc.Annotations["kusk-gateway/openapi-url"])
+	if err != nil {
+		return ctrl.Result{}, err
+	}
+
+	var yml map[string]interface{}
+	err = yaml.Unmarshal(openapi, &yml)
+	if err != nil {
+		return ctrl.Result{}, err
+	}
+
+	service := map[string]interface{}{"service": map[string]interface{}{
+		"name":      req.Name,
+		"namespace": req.Namespace,
+		"port":      svc.Spec.Ports[0].Port,
+	}}
+	upstream := map[string]interface{}{
+		"upstream": service,
+	}
+
+	if _, ok := yml["x-kusk"]; !ok {
+		yml["x-kusk"] = upstream
+	}
+
+	kusk := yml["x-kusk"]
+	if xkusk, ok := kusk.(map[string]interface{}); ok {
+		if _, contains := xkusk["upstream"]; !contains {
+			xkusk["upstream"] = service
+		}
+	}
+
+	yamlPayload, err := yaml.Marshal(yml)
+	if err != nil {
+		return ctrl.Result{}, err
+	}
+
+	gatewaySpec := gateway.APISpec{
+		Spec: string(yamlPayload),
+	}
+
+	api := &gateway.API{}
+	if err := r.Client.Get(ctx, client.ObjectKey{Namespace: req.Namespace, Name: req.Name}, api); err != nil && errors.IsNotFound(err) {
+		//create
+		api.Name = req.Name
+		api.Namespace = req.Namespace
+		api.Spec = gatewaySpec
+		if err := r.Client.Create(ctx, api, &client.CreateOptions{}); err != nil {
+			l.Error(err, "error occured while creating API")
+			return ctrl.Result{}, err
+		}
+
+		return ctrl.Result{}, nil
+	}
+
+	api.Spec = gatewaySpec
+	if err := r.Client.Update(ctx, api, &client.UpdateOptions{}); err != nil {
+		l.Error(err, "error occured while updating API")
+		return ctrl.Result{}, err
+
+	}
+
+	return ctrl.Result{}, nil
+}
+
+// SetupWithManager sets up the controller with the Manager.
+func (r *ServiceReconciler) SetupWithManager(mgr ctrl.Manager) error {
+	return ctrl.NewControllerManagedBy(mgr).
+		For(&corev1.Service{}).
+		Complete(r)
+}
+
+func getOpenAPIfromURL(u string) ([]byte, error) {
+	if _, err := url.Parse(u); err != nil {
+		return nil, fmt.Errorf("invalid url %s: %w", u, err)
+	}
+
+	resp, err := http.Get(u)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	b, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	return b, err
+}