feat(operator): add deployment mutation hook

fixes #528

pkg/webhook/webhook.go

@@ -0,0 +1,113 @@
+package webhook
+
+import (
+	"encoding/json"
+	"time"
+
+	istiov1alpha1 "github.com/maistra/istio-workspace/pkg/apis/maistra/v1alpha1"
+	"github.com/maistra/istio-workspace/pkg/internal/session"
+	"github.com/maistra/istio-workspace/pkg/model"
+	admission "k8s.io/api/admission/v1"
+	appsv1 "k8s.io/api/apps/v1"
+)
+
+type data struct {
+	Object appsv1.Deployment
+}
+
+func (d *data) IsIkeable() bool {
+	return d.Object.Labels["ike.target"] != ""
+}
+
+func (d *data) Join() bool {
+	_, ok := d.Object.Labels["ike.session"]
+	return ok
+}
+
+func (d *data) Target() string {
+	return d.Object.Labels["ike.target"]
+}
+
+func (d *data) Session() string {
+	return d.Object.Labels["ike.session"]
+}
+
+func (d *data) Namespace() string {
+	return d.Object.Namespace
+}
+
+func Hook(review admission.AdmissionReview) admission.AdmissionReview {
+
+	// if review.Request.DryRun don't do stuff with sideeffects....
+
+	data, err := parseRequest(review.Request)
+	if err != nil {
+		// TODO: createErrorReview
+	}
+
+	if !data.IsIkeable() {
+		review.Response = &admission.AdmissionResponse{
+			UID:     review.Request.UID,
+			Allowed: true,
+		}
+		return review
+	}
+
+	session, err := createSessionAndWait(data)
+	if err != nil {
+		// TODO: createErrorReview
+	}
+
+	patch := createLabelsPatch(session)
+
+	patchType := admission.PatchTypeJSONPatch
+	review.Response = &admission.AdmissionResponse{
+		UID:       review.Request.UID,
+		Allowed:   true,
+		PatchType: &patchType,
+		Patch:     []byte(patch),
+	}
+	return review
+}
+
+func parseRequest(request *admission.AdmissionRequest) (data, error) {
+	var dep appsv1.Deployment
+
+	err := json.Unmarshal(request.Object.Raw, &dep)
+	if err != nil {
+		return data{}, err
+	}
+	return data{
+		Object: dep,
+	}, nil
+}
+
+func createSessionAndWait(d data) (*istiov1alpha1.RefStatus, error) {
+	checkDuration := time.Millisecond * 100
+	options := session.Options{
+		DeploymentName: d.Target(),
+		SessionName:    d.Session(),
+		NamespaceName:  d.Namespace(),
+		Strategy:       model.StrategyExisting,
+		Duration:       &checkDuration,
+		// TODO: add support for what to wait for WaitExpression: FoundDeployment
+	}
+
+	c, err := session.DefaultClient(options.NamespaceName)
+	if err != nil {
+		return nil, err
+	}
+
+	state, remove, err := session.CreateOrJoinHandler(options, c)
+	if err != nil {
+		remove()
+		return nil, err
+	}
+
+	return &state.RefStatus, nil
+}
+
+func createLabelsPatch(ref *istiov1alpha1.RefStatus) string {
+	// for each Resource, if Deployment, Make label path
+	return ""
+}