capsule/internal/webhook/namespace/validation/prefix.go

// Copyright 2020-2026 Project Capsule Authors
// SPDX-License-Identifier: Apache-2.0

package validation

import (
	"context"
	"fmt"
	"strings"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/client-go/tools/events"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"

	capsulev1beta2 "github.com/projectcapsule/capsule/api/v1beta2"
	"github.com/projectcapsule/capsule/pkg/runtime/configuration"
	evt "github.com/projectcapsule/capsule/pkg/runtime/events"
	"github.com/projectcapsule/capsule/pkg/runtime/handlers"
)

type prefixHandler struct {
	cfg configuration.Configuration
}

func PrefixHandler(configuration configuration.Configuration) handlers.TypedHandlerWithTenant[*corev1.Namespace] {
	return &prefixHandler{
		cfg: configuration,
	}
}

func (h *prefixHandler) OnCreate(
	c client.Client,
	ns *corev1.Namespace,
	decoder admission.Decoder,
	recorder events.EventRecorder,
	tnt *capsulev1beta2.Tenant,
) handlers.Func {
	return func(ctx context.Context, req admission.Request) *admission.Response {
		if exp, _ := h.cfg.ProtectedNamespaceRegexp(); exp != nil {
			if matched := exp.MatchString(ns.GetName()); matched {
				response := admission.Denied(fmt.Sprintf("Creating namespaces with name matching %s regexp is not allowed; please, reach out to the system administrators", exp.String()))

				return &response
			}
		}

		if h.cfg.ForceTenantPrefix() {
			if tnt.Spec.ForceTenantPrefix != nil && !*tnt.Spec.ForceTenantPrefix {
				return nil
			}

			if e := fmt.Sprintf("%s-%s", tnt.GetName(), ns.GetName()); !strings.HasPrefix(ns.GetName(), fmt.Sprintf("%s-", tnt.GetName())) {
				recorder.Eventf(tnt, ns, corev1.EventTypeWarning, evt.ReasonInvalidTenantPrefix, evt.ActionValidationDenied, "Namespace %s does not match the expected prefix for the current Tenant", ns.GetName())

				response := admission.Denied(fmt.Sprintf("The namespace doesn't match the tenant prefix, expected %s", e))

				return &response
			}
		}

		return nil
	}
}

func (h *prefixHandler) OnUpdate(
	client.Client,
	*corev1.Namespace,
	*corev1.Namespace,
	admission.Decoder,
	events.EventRecorder,
	*capsulev1beta2.Tenant,
) handlers.Func {
	return func(context.Context, admission.Request) *admission.Response {
		return nil
	}
}

func (h *prefixHandler) OnDelete(
	client.Client,
	*corev1.Namespace,
	admission.Decoder,
	events.EventRecorder,
	*capsulev1beta2.Tenant,
) handlers.Func {
	return func(context.Context, admission.Request) *admission.Response {
		return nil
	}
}