Installation

Kyverno can be installed using Helm or deploying from the YAML manifests directly. When using either of these methods, there are no other steps required to get Kyverno up and running.

Install Kyverno using Helm

Add the Kyverno Helm repository.

helm repo add kyverno https://kyverno.github.io/kyverno/

Scan the new repository for charts.

helm repo update

Use Helm 3.2+ to create a namespace and install Kyverno:

helm install kyverno --namespace kyverno kyverno/kyverno --create-namespace

To install non-stable releases, add the --devel switch to Helm

helm install kyverno --namespace kyverno kyverno/kyverno --create-namespace --devel

For Helm versions prior to 3.2, create a namespace and then install the Kyverno Helm chart.

kubectl create ns kyverno
helm install kyverno --namespace kyverno kyverno/kyverno

Install Kyverno using YAMLs

If you’d rather deploy the manifest directly, simply apply the latest release file. This manifest path will always point to the latest release, including release candidates and other non-stable releases.

kubectl create -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Customize the installation of Kyverno

If you wish to customize the installation of Kyverno to have certificates signed by an internal or trusted CA, or to otherwise learn how the components work together, follow the below guide.

The Kyverno policy engine runs as an admission webhook and requires a CA-signed certificate and key to setup secure TLS communication with the kube-apiserver (the CA can be self-signed). There are two ways to configure secure communications between Kyverno and the kube-apiserver.

Option 1: Auto-generate a self-signed CA and certificate

Kyverno can automatically generate a new self-signed Certificate Authority (CA) and a CA signed certificate to use for webhook registration. This is the default behavior when installing Kyverno, and when done the certificate validity period is 10 years.

## Install Kyverno
kubectl create -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Also, by default Kyverno is installed in the “kyverno” namespace. To install it in a different namespace, you can edit install.yaml and update the namespace.

To check the Kyverno controller status, run the command:

## Check pod status
kubectl get pods -n <namespace>

If the Kyverno controller is not running, you can check its status and logs for errors:

kubectl describe pod <kyverno-pod-name> -n <namespace>

kubectl logs <kyverno-pod-name> -n <namespace>

Option 2: Use your own CA-signed certificate

You can install your own CA-signed certificate, or generate a self-signed CA and use it to sign a certificate. Once you have a CA and X.509 certificate-key pair, you can install these as Kubernetes secrets in your cluster. If Kyverno finds these secrets, it uses them. Otherwise it will request the kube-controller-manager to generate a certificate (see Option 1 above).

2.1. Generate a self-signed CA and signed certificate-key pair

If you already have a CA and a signed certificate, you can directly proceed to Step 2.

Here are the commands to create a self-signed root CA, and generate a signed certificate and key using OpenSSL (you can customize the certificate attributes for your deployment):

1. Create a self-signed CA

openssl genrsa -out rootCA.key 4096
openssl req -x509 -new -nodes -key rootCA.key -sha256 -days 1024 -out rootCA.crt  -subj "/C=US/ST=test/L=test /O=test /OU=PIB/CN=*.kyverno.svc/emailAddress=test@test.com"

2. Create a keypair

openssl genrsa -out webhook.key 4096
openssl req -new -key webhook.key -out webhook.csr  -subj "/C=US/ST=test /L=test /O=test /OU=PIB/CN=kyverno-svc.kyverno.svc/emailAddress=test@test.com"

3. Create a webhook.ext file with the Subject Alternate Names (SAN) to use. This is required with Kubernetes 1.19+ and Go 1.15+.

subjectAltName = DNS:kyverno-svc,DNS:kyverno-svc.kyverno,DNS:kyverno-svc.kyverno.svc

4. Sign the keypair with the CA passing in the extension

openssl x509 -req -in webhook.csr -CA rootCA.crt -CAkey rootCA.key -CAcreateserial -out webhook.crt -days 1024 -sha256 -extfile webhook.ext

5. Verify the contents of the certificate

 openssl x509 -in webhook.crt -text -noout

The certificate must contain the SAN information in the X509v3 extensions section:

X509v3 extensions:
    X509v3 Subject Alternative Name:
        DNS:kyverno-svc, DNS:kyverno-svc.kyverno, DNS:kyverno-svc.kyverno.svc

2.2. Configure secrets for the CA and TLS certificate-key pair

You can now use the following files to create secrets:

• rootCA.crt
• webhooks.crt
• webhooks.key

To create the required secrets, use the following commands (do not change the secret names):

kubectl create ns <namespace>
kubectl create secret tls kyverno-svc.kyverno.svc.kyverno-tls-pair --cert=webhook.crt --key=webhook.key -n <namespace>
kubectl annotate secret kyverno-svc.kyverno.svc.kyverno-tls-pair self-signed-cert=true -n <namespace>
kubectl create secret generic kyverno-svc.kyverno.svc.kyverno-tls-ca --from-file=rootCA.crt -n <namespace>

Kyverno uses secrets created above to setup TLS communication with the kube-apiserver and specify the CA bundle to be used to validate the webhook server’s certificate in the admission webhook configurations.

This process has been automated for you with a simple script that generates a self-signed CA, a TLS certificate-key pair, and the corresponding Kubernetes secrets: helper script

2.3. Install Kyverno

You can now install Kyverno by downloading and updating install.yaml, or using the command below (assumes that the namespace is “kyverno”):

kubectl create -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Configuring Kyverno

Permissions

Kyverno, in foreground mode, leverages admission webhooks to manage incoming API requests, and background mode applies the policies on existing resources. It uses ServiceAccount kyverno-service-account, which is bound to multiple ClusterRoles, which defines the default resources and operations that are permitted.

ClusterRoles used by Kyverno:

• kyverno:webhook
• kyverno:userinfo
• kyverno:customresources
• kyverno:policycontroller
• kyverno:generatecontroller

The generate rule creates a new resource, and to allow Kyverno to create resources the Kyverno ClusterRole needs permissions to create/update/delete. This can be done by adding the resource to the ClusterRole kyverno:generatecontroller used by Kyverno or by creating a new ClusterRole and a ClusterRoleBinding to Kyverno’s default ServiceAccount.

apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: kyverno:generatecontroller
rules:
- apiGroups:
  - "*"
  resources:
  - namespaces
  - networkpolicies
  - secrets
  - configmaps
  - resourcequotas
  - limitranges
  - ResourceA # new Resource to be generated
  - ResourceB
  verbs:
  - create # generate new resources
  - get # check the contents of exiting resources
  - update # update existing resource, if required configuration defined in policy is not present
  - delete # clean-up, if the generate trigger resource is deleted

kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
  name: kyverno-admin-generate
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: kyverno:generatecontroller # clusterRole defined above, to manage generated resources
subjects:
- kind: ServiceAccount
  name: kyverno-service-account # default kyverno serviceAccount
  namespace: kyverno

Version

To install a specific version, download install.yaml and then change the image tag.

e.g., change image tag from latest to the specific tag v1.3.0.

spec:
  containers:
    - name: kyverno
      # image: ghcr.io/kyverno/kyverno:latest
      image: ghcr.io/kyverno/kyverno:v1.3.0

To install in a specific namespace replace the namespace “kyverno” with your namespace.

Example:

apiVersion: v1
kind: Namespace
metadata:
  name: <namespace>

apiVersion: v1
kind: Service
metadata:
  labels:
    app: kyverno
  name: kyverno-svc
  namespace: <namespace>

and in other places (ServiceAccount, ClusterRoles, ClusterRoleBindings, ConfigMaps, Service, Deployment) where Namespace is mentioned.

Alternatively, use Kustomize to replace the Namespace.

To run Kyverno:

kubectl create -f ./install.yaml

To check the Kyverno controller status, run the command:

kubectl get pods -n <namespace>

If the Kyverno controller is not running, you can check its status and logs for errors:

kubectl describe pod <kyverno-pod-name> -n <namespace>

kubectl logs -l app=kyverno -n <namespace>

Flags

The following flags are used to control the behavior of Kyverno and must be set in the Kyverno ConfigMap.

1. excludeGroupRole: excludeGroupRole role expected string with comma-separated group role. It will exclude all the group role from the user request. Default we are using system:serviceaccounts:kube-system,system:nodes,system:kube-scheduler.
2. excludeUsername: excludeUsername expected string with comma-separated kubernetes username. In generate request if user enable Synchronize in generate policy then only kyverno can update/delete generated resource but admin can exclude specific username who have access of delete/update generated resource.
3. filterK8Resources: Kubernetes resources in the format “[kind,namespace,name]” where the policy is not evaluated by the admission webhook. For example –filterKind “[Deployment, kyverno, kyverno]” –filterKind “[Deployment, kyverno, kyverno],[Events, *, *]”.

PolicyViolation access

During the Kyverno installation, it creates a ClusterRole kyverno:policyviolations which has the list,get,watch operations on resource policyviolations. To grant access to a Namespace admin, configure the following YAML file then apply to the cluster.

• Replace metadata.namespace with Namespace of the admin
• Configure subjects field to bind admin’s role to the ClusterRole policyviolation

apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
  name: policyviolation
  # change namespace below to create rolebinding for the namespace admin
  namespace: default
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: policyviolation
subjects:
# configure below to access policy violation for the namespace admin
- kind: ServiceAccount
  name: default
  namespace: default
# - apiGroup: rbac.authorization.k8s.io
#   kind: User
#   name:
# - apiGroup: rbac.authorization.k8s.io
#   kind: Group
#   name:

Resource Filters

The admission webhook checks if a policy is applicable on all admission requests. The Kubernetes kinds that are not processed can be filtered by adding a ConfigMap in namespace kyverno and specifying the resources to be filtered under data.resourceFilters. The default name of this ConfigMap is init-config but can be changed by modifying the value of the environment variable INIT_CONFIG in the Kyverno deployment spec. data.resourceFilters must be a sequence of one or more [<Kind>,<Namespace>,<Name>] entries with * as a wildcard. Thus, an item [Node,*,*] means that admissions of Node in any namespace and with any name will be ignored.

By default we have specified Nodes, Events, APIService, and SubjectAccessReview as the kinds to be skipped in the default configuration in install.yaml.

apiVersion: v1
kind: ConfigMap
metadata:
  name: init-config
  namespace: kyverno
data:
  # resource types to be skipped by kyverno policy engine
  resourceFilters: "[Event,*,*][*,kube-system,*][*,kube-public,*][*,kube-node-lease,*][Node,*,*][APIService,*,*][TokenReview,*,*][SubjectAccessReview,*,*][*,kyverno,*]"

To modify the ConfigMap, either directly edit the ConfigMap init-config in the default configuration inside install.yaml and redeploy it or modify the ConfigMap using kubectl. Changes to the ConfigMap through kubectl will automatically be picked up at runtime.

Upgrading Kyverno

Upgrading Kyverno is as simple as applying the new YAML manifest, or using Helm depending on how it was installed.

Upgrade Kyverno with YAML manifest

Apply the new manifest over the existing installation.

kubectl apply -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Upgrade Kyverno with Helm

Kyverno can be upgraded like any other Helm chart.

Scan your Helm repositories for updated charts.

helm repo update

Show the versions of the Kyverno chart which are available. To see pre-release charts, add the --devel flag to the helm command.

helm search repo kyverno

Run the upgrade command picking the target version.

helm upgrade kyverno --namespace kyverno kyverno/kyverno --version <version_number>

Uninstalling Kyverno

To uninstall Kyverno, use either the raw YAML manifest or Helm. The Kyverno deployment and all CRDs will be removed, including any reports.

Uninstall Kyverno with YAML manifest

kubectl delete -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Uninstall Kyverno with Helm

helm uninstall kyverno --namespace kyverno kyverno/kyverno