Update README.md

README.md

@@ -7,3 +7,51 @@
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+
+The **k8s-generic-webhook** is a library to simplify the implementation of webhooks for arbitrary customer resources (CR) in the [operator-sdk](https://sdk.operatorframework.io/) or [controller-runtime](https://github.com/kubernetes-sigs/controller-runtime).
+Furthermore, it provides full access to the `AdmissionReview` request and decodes the `Object` in the request automatically. More sophistic webhook logic is facilitated by using the injected `Client` of the webhook which provides full access to the Kubernetes API.
+
+## Quickstart
+1. Initialize a new manager using the [operator-sdk](https://sdk.operatorframework.io/).
+2. Create a pkg (e.g. `webhooks/pod`) and implement your webhook logic by embedding either the `ValidatingWebhook` or the `MuatatingWebhook`.
+
+```go
+package pod
+
+import (
+	"context"
+
+	"github.com/snorwin/k8s-generic-webhook/pkg/webhook"
+	corev1 "k8s.io/api/core/v1"
+	"sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/manager"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+)
+
+type Webhook struct {
+	webhook.ValidatingWebhook
+}
+
+func (w *Webhook) SetupWebhookWithManager(mgr manager.Manager) error {
+	return webhook.NewGenericWebhookManagedBy(mgr).
+		For(&corev1.Pod{}).
+		Complete(w)
+}
+
+func (w *Webhook) ValidateCreate(ctx context.Context, req admission.Request) admission.Response {
+	_ = log.FromContext(ctx)
+
+	pod := req.Object.Object.(*corev1.Pod)
+	// TODO add your programmatic validation logic here
+
+	return admission.Allowed("")
+}
+```
+
+3. Add the following snippet to `main()` in `main.go` in order to register the webhook in the manager.
+```go
+if err = (&pod.Webhook{}).SetupWebhookWithManager(mgr); err != nil {
+    setupLog.Error(err, "unable to create webhook", "webhook", "Pod")
+    os.Exit(1)
+}
+```