Depending on the application used to either install and manage Kyverno or the Kubernetes platform on which the cluster is built, there are some specific considerations of which to be aware. These notes are provided assuming the Helm chart is the installation artifact used.
Notes for ArgoCD users
When deploying the Kyverno Helm chart with ArgoCD, you will need to enable
Replace in the
syncOptions. You may want to also ignore differences in aggregated ClusterRoles which Kyverno uses by default. Aggregated ClusterRoles are built by aggregating other ClusterRoles in the cluster and are dynamic by nature, therefore desired and observed states cannot match.
You can do so by following instructions in these pages of the ArgoCD documentation:
ArgoCD uses Helm only for templating but applies the results with
kubectl adds metadata that exceeds the limit allowed by Kubernetes. Using
Replace overcomes this limitation. Another option is to use server-side apply, supported in ArgoCD v2.5+.
Below is an example of an ArgoCD Application manifest that should work with the Kyverno Helm chart:
1apiVersion: argoproj.io/v1alpha1 2kind: Application 3metadata: 4 name: kyverno 5 namespace: argocd 6spec: 7 destination: 8 namespace: kyverno 9 server: https://kubernetes.default.svc 10 project: default 11 source: 12 chart: kyverno 13 repoURL: https://kyverno.github.io/kyverno 14 targetRevision: 2.6.0 15 syncPolicy: 16 automated: 17 prune: true 18 selfHeal: true 19 syncOptions: 20 - CreateNamespace=true 21 - Replace=true
For considerations when using Argo CD along with Kyverno mutate policies, see the documentation here.
ArgoCD automatically sets the
app.kubernetes.io/instance label and uses it to determine which resources form the app. The Kyverno Helm chart also sets this label for the same purposes. In order to resolve this conflict, configure ArgoCD to use a different tracking mechanism as described in the ArgoCD documentation.
Notes for OpenShift Users
Red Hat OpenShift contains a feature called Security Context Constraints (SCC) which enforces certain security controls in a profile-driven manner. An OpenShift cluster contains several of these out of the box with OpenShift 4.11 preferring
restricted-v2 by default. The Kyverno Helm chart defines its own values for the Pod’s
securityContext object which, although it conforms to the upstream Pod Security Standards’ restricted profile, may potentially be incompatible with your defined Security Context Constraints. Deploying the Kyverno Helm chart as-is on an OpenShift environment may result in an error similar to “unable to validate against any security context constraint”. In order to get past this, deploy the Kyverno Helm chart with with the required securityContext flags/fields set to a value of
null. OpenShift will apply the defined SCC upon deployment. If on OpenShift 4.11+, the
restricted-v2 profile is known to allow for successful deployment of the chart without modifying the Helm chart installation process.
Notes for EKS Users
For EKS clusters built with the VPC CNI plug-in, if you wish to opt for the operability strategy as defined in the Security vs Operability section, during the installation of Kyverno you should exclude the
kube-system Namespace from webhooks as this is the Namespace where the plug-in runs. In situations where all the cluster Nodes are “deleted” (ex., only one node group in the cluster which is scaled to zero), which also impacts where the Kyverno replicas run, if
kube-system is not excluded and where at least one policy in
Fail mode matches on Pods, the VPC CNI plug-in’s DaemonSet Pods may not be able to come online to finish the Node bootstrapping process. If this situation occurs, because the underlying cluster network cannot return to a healthy state, Kyverno will be unable to service webhook requests.
Notes for AKS Users
AKS uses an Admission Enforcer control the webhooks in an AKS cluster and will remove those that may impact system Namespaces. Since Kyverno registers as a webhook, this Admission Enforcer may remove Kyverno’s webhook causing the two to fight over webhook reconciliation. See this Microsoft Azure FAQ for further information. When deploying Kyverno on an AKS cluster, set the Helm option
config.webhookAnnotations to include the necessary annotation to disable the Admission Enforcer. Kyverno will configure its webhooks with this annotation to prevent their removal by AKS. The annotation that should be used is
"admissions.enforcer/disabled": true. See the chart README for more information.