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handler.go
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handler.go
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// SPDX-FileCopyrightText: 2024 SAP SE or an SAP affiliate company and Gardener contributors
//
// SPDX-License-Identifier: Apache-2.0
package kubernetesservicehost
import (
"context"
"fmt"
"github.com/go-logr/logr"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/runtime"
"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
kubernetesutils "github.com/gardener/gardener/pkg/utils/kubernetes"
)
// Handler handles admission requests and injects the KUBERNETES_SERVICE_HOST environment variable into all containers
// in pods.
type Handler struct {
Logger logr.Logger
Host string
}
// Default injects the KUBERNETES_SERVICE_HOST environment variable into all containers in the pod.
func (h *Handler) Default(ctx context.Context, obj runtime.Object) error {
pod, ok := obj.(*corev1.Pod)
if !ok {
return fmt.Errorf("expected *corev1.Pod but got %T", obj)
}
req, err := admission.RequestFromContext(ctx)
if err != nil {
return err
}
log := h.Logger.WithValues("pod", kubernetesutils.ObjectKeyForCreateWebhooks(pod, req))
log.Info("Injecting KUBERNETES_SERVICE_HOST environment variable into all containers in the pod")
h.mutateContainers(pod.Spec.InitContainers)
h.mutateContainers(pod.Spec.Containers)
return nil
}
func (h *Handler) mutateContainers(containers []corev1.Container) {
for i, container := range containers {
if hasEnv(container.Env) {
continue
}
if container.Env == nil {
container.Env = make([]corev1.EnvVar, 0, 1)
}
containers[i].Env = append(containers[i].Env, corev1.EnvVar{
Name: "KUBERNETES_SERVICE_HOST",
Value: h.Host,
ValueFrom: nil,
})
}
}
func hasEnv(envVars []corev1.EnvVar) bool {
for _, env := range envVars {
if env.Name == "KUBERNETES_SERVICE_HOST" {
return true
}
}
return false
}