feat: enforcing Pod Priority Class

api/v1alpha1/domain/podpriority.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2020 Clastix Labs.
+
+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 domain
+
+import (
+	"regexp"
+	"strings"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/clastix/capsule/api/v1alpha1"
+)
+
+const (
+	podPriorityAllowedAnnotation      = "priorityclass.capsule.clastix.io/allowed"
+	podPriorityAllowedRegexAnnotation = "priorityclass.capsule.clastix.io/allowed-regex"
+)
+
+func NewPodPriority(object metav1.Object) (allowed *v1alpha1.AllowedListSpec) {
+	annotations := object.GetAnnotations()
+
+	if v, ok := annotations[podPriorityAllowedAnnotation]; ok {
+		allowed = &v1alpha1.AllowedListSpec{}
+		allowed.Exact = strings.Split(v, ",")
+	}
+
+	if v, ok := annotations[podPriorityAllowedRegexAnnotation]; ok {
+		if _, err := regexp.Compile(v); err == nil {
+			if allowed == nil {
+				allowed = &v1alpha1.AllowedListSpec{}
+			}
+			allowed.Regex = v
+		}
+	}
+
+	return
+}

main.go

@@ -24,7 +24,6 @@ import (
 	goRuntime "runtime"
 
 	flag "github.com/spf13/pflag"
-
 	"go.uber.org/zap/zapcore"
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
@@ -45,6 +44,7 @@ import (
 	"github.com/clastix/capsule/pkg/webhook/namespacequota"
 	"github.com/clastix/capsule/pkg/webhook/networkpolicies"
 	"github.com/clastix/capsule/pkg/webhook/ownerreference"
+	"github.com/clastix/capsule/pkg/webhook/podpriority"
 	"github.com/clastix/capsule/pkg/webhook/pvc"
 	"github.com/clastix/capsule/pkg/webhook/registry"
 	"github.com/clastix/capsule/pkg/webhook/services"
@@ -176,6 +176,7 @@ func main() {
 		ingress.Webhook(ingress.Handler(allowIngressHostnamesCollision)),
 		pvc.Webhook(pvc.Handler()),
 		registry.Webhook(registry.Handler()),
+		podpriority.Webhook(podpriority.Handler()),
 		services.Webhook(services.Handler()),
 		ownerreference.Webhook(utils.InCapsuleGroups(capsuleGroups, ownerreference.Handler(forceTenantPrefix))),
 		namespacequota.Webhook(utils.InCapsuleGroups(capsuleGroups, namespacequota.Handler())),

pkg/webhook/podpriority/errors.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2020 Clastix Labs.
+
+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 podpriority
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/clastix/capsule/api/v1alpha1"
+)
+
+type podPriorityClassForbidden struct {
+	priorityClassName string
+	spec              v1alpha1.AllowedListSpec
+}
+
+func NewPodPriorityClassForbidden(priorityClassName string, spec v1alpha1.AllowedListSpec) error {
+	return &podPriorityClassForbidden{
+		priorityClassName: priorityClassName,
+		spec:              spec,
+	}
+}
+
+func (f podPriorityClassForbidden) Error() (err string) {
+	err = fmt.Sprintf("Pod Priorioty Class %s is forbidden for the current Tenant: ", f.priorityClassName)
+	var extra []string
+	if len(f.spec.Exact) > 0 {
+		extra = append(extra, fmt.Sprintf("use one from the following list (%s)", strings.Join(f.spec.Exact, ", ")))
+	}
+	if len(f.spec.Regex) > 0 {
+		extra = append(extra, fmt.Sprintf(" use one matching the following regex (%s)", f.spec.Regex))
+	}
+	err += strings.Join(extra, " or ")
+	return
+}

pkg/webhook/podpriority/validating.go

@@ -0,0 +1,111 @@
+/*
+Copyright 2020 Clastix Labs.
+
+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 podpriority
+
+import (
+	"context"
+	"net/http"
+
+	v1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/fields"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	capsulev1alpha1 "github.com/clastix/capsule/api/v1alpha1"
+	"github.com/clastix/capsule/api/v1alpha1/domain"
+	capsulewebhook "github.com/clastix/capsule/pkg/webhook"
+)
+
+// +kubebuilder:webhook:path=/validating-v1-podpriority,mutating=false,sideEffects=None,admissionReviewVersions=v1,failurePolicy=ignore,groups="",resources=pods,verbs=create,versions=v1,name=podpriority.capsule.clastix.io
+
+type webhook struct {
+	handler capsulewebhook.Handler
+}
+
+func Webhook(handler capsulewebhook.Handler) capsulewebhook.Webhook {
+	return &webhook{handler: handler}
+}
+
+func (w *webhook) GetName() string {
+	return "podpriority"
+}
+
+func (w *webhook) GetPath() string {
+	return "/validating-v1-podpriority"
+}
+
+func (w *webhook) GetHandler() capsulewebhook.Handler {
+	return w.handler
+}
+
+type handler struct {
+}
+
+func Handler() capsulewebhook.Handler {
+	return &handler{}
+}
+
+func (h *handler) OnCreate(c client.Client, decoder *admission.Decoder) capsulewebhook.Func {
+	return func(ctx context.Context, req admission.Request) admission.Response {
+		var pod = &v1.Pod{}
+
+		if err := decoder.Decode(req, pod); err != nil {
+			return admission.Errored(http.StatusBadRequest, err)
+		}
+
+		var tntList = &capsulev1alpha1.TenantList{}
+
+		if err := c.List(ctx, tntList, client.MatchingFieldsSelector{
+			Selector: fields.OneTermEqualSelector(".status.namespaces", pod.Namespace),
+		}); err != nil {
+			return admission.Errored(http.StatusBadRequest, err)
+		}
+
+		if len(tntList.Items) == 0 {
+			return admission.Allowed("")
+		}
+
+		var allowed = domain.NewPodPriority(&tntList.Items[0])
+
+		var priorityClassName = pod.Spec.PriorityClassName
+
+		switch {
+		case allowed == nil:
+			// Enforcement is not in place, skipping it at all
+			return admission.Allowed("")
+		case len(priorityClassName) == 0:
+			// We don't have to force Pod to specify a Priority Class
+			return admission.Allowed("")
+		case !allowed.ExactMatch(priorityClassName) && !allowed.RegexMatch(priorityClassName):
+			return admission.Errored(http.StatusBadRequest, NewPodPriorityClassForbidden(priorityClassName, *allowed))
+		default:
+			return admission.Allowed("")
+		}
+	}
+}
+
+func (h *handler) OnDelete(client client.Client, decoder *admission.Decoder) capsulewebhook.Func {
+	return func(ctx context.Context, req admission.Request) admission.Response {
+		return admission.Allowed("")
+	}
+}
+
+func (h *handler) OnUpdate(client client.Client, decoder *admission.Decoder) capsulewebhook.Func {
+	return func(ctx context.Context, req admission.Request) admission.Response {
+		return admission.Allowed("")
+	}
+}