This repository contains a small HTTP server that can be used as a Kubernetes MutatingAdmissionWebhook.
A cluster on which this example can be tested must be running Kubernetes 1.24.0 or above,
with the admissionregistration.k8s.io/v1
API enabled. You can verify that by observing that the
following command produces a non-empty output:
kubectl api-versions | grep admissionregistration.k8s.io/v1
In addition, the MutatingAdmissionWebhook
admission controller should be added and listed in the admission-control
flag of kube-apiserver
.
For building the image, GNU make and Go are required.
To issue and sign certificates, cert-manager must be deployed to the cluster before the webhook. To deploy cert-manager, these steps can be followed:
$ kubectl create namespace cert-manager # cert-manager is the default namespace
$ kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.11.0/cert-manager.yaml
To verify the cert-manager api, run $cmctl check api
.
- Bring up a Kubernetes cluster satisfying the above prerequisites, and make
sure it is active (i.e., either via the configuration in the default location, or by setting
the
KUBECONFIG
environment variable). - Create the webhook namespace:
$ kubectl create namespace webhook-demo
- Deploy all webhook resources:
$ kubectl apply -n webhook-demo -f deployment/deployment.yaml.template
- The
webhook-server
pod in thewebhook-demo
namespace should be running:
$ kubectl -n webhook-demo get pods
NAME READY STATUS RESTARTS AGE
webhook-server-6f976f7bf-hssc9 1/1 Running 0 35m
- A
MutatingWebhookConfiguration
nameddemo-webhook
should exist:
$ kubectl get mutatingwebhookconfigurations | grep webhook-server
NAME AGE
demo-webhook 36m
- Deploy a pod that has all necessary transparency information:
$ kubectl create -f examples/pod-with-information.yaml
Verify that the pod has the transparency information in its annotations:
$ kubectl get pod/pod-with-information -o yaml | grep annotations -A 3
...
annotations:
purposes: given
dataCategories: given
...
- Deploy a pod that has some the transparency tags but is missing
dataCategories
:
$ kubectl create -f examples/pod-with-override.yaml
$ kubectl get pod/pod-with-override -o yaml | grep annotations -A 3
...
annotations:
purposes: given
dataCategories: unspecified
...
- Deploy a pod which disallows deployment outside of the EU. This only applies to GKE clusters.
$ kubectl create -f examples/pod-with-conflict.yaml
If the cluster is running in zones outside of the EU, the deployment will be rejected and return an error. If not, the deployment will pass and can be verified with:
$ kubectl get pod/pod-with-conflict -o yaml | grep annotations -A 3
...
annotations:
purposes: given
dataCategories: unspecified
...
An image can be built by running make
.
If you want to modify the webhook server for testing purposes, be sure to set and export
the shell environment variable IMAGE
to an image tag for which you have push access. You can then
build and push the image by running make push-image
. Also make sure to change the image tag
in deployment/deployment.yaml.template
, and if necessary, add image pull secrets.