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.

Compatibility Matrix

* Kyverno CLI 1.3.0 supports up to Kubernetes 1.18.

Install Kyverno using Helm

Kyverno can be deployed through a Helm chart which is accessible either through the Kyverno repo or on ArtifactHub. As of Kyverno 1.3.2, the Helm chart also by default installs the default profile of the Pod Security Standards policies available here.

In order to install Kyverno with Helm, first add the Kyverno Helm repository.

1helm repo add kyverno https://kyverno.github.io/kyverno/

Scan the new repository for charts.

1helm repo update

Use Helm 3.2+ to create a Namespace and install Kyverno.

Beginning with Kyverno 1.4.2, Kyverno Helm chart v2.0.2, the Kyverno CRDs must be added seperately and before Kyverno is installed.

1helm install kyverno-crds kyverno/kyverno-crds --namespace kyverno --create-namespace

Use Kyverno 1.4.2+ to create a customizable Helm release name while installing Kyverno. Before Kyverno 1.4.2, the Helm release name must be Kyverno.

1helm install kyverno kyverno/kyverno --namespace kyverno

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

1helm install kyverno-crds kyverno/kyverno-crds --namespace kyverno --create-namespace --devel
2helm install kyverno kyverno/kyverno --namespace kyverno --devel

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

1kubectl create namespace kyverno
2helm install kyverno-crds kyverno/kyverno-crds --namespace kyverno
3helm install kyverno kyverno/kyverno --namespace 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.

1kubectl create -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Customize the installation of Kyverno

The picture below shows shows a typical Kyverno installation:

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.

1## Install Kyverno
2kubectl 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:

1## Check pod status
2kubectl get pods -n <namespace>

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

1kubectl describe pod <kyverno-pod-name> -n <namespace>

1kubectl 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

1openssl genrsa -out rootCA.key 4096
2openssl 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

1openssl genrsa -out webhook.key 4096
2openssl 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

1openssl 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

1 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):

1kubectl create ns <namespace>
2kubectl create secret tls kyverno-svc.kyverno.svc.kyverno-tls-pair --cert=webhook.crt --key=webhook.key -n <namespace>
3kubectl annotate secret kyverno-svc.kyverno.svc.kyverno-tls-pair self-signed-cert=true -n <namespace>
4kubectl 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”):

1kubectl 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.

To get cluster wide permissions, users must add the permissions for cluster wide resource such as roles, clusterroles, rolebindings and clusterrolebindings they need.

 1apiVersion: rbac.authorization.k8s.io/v1beta1
 2kind: ClusterRole
 3metadata:
 4  name: kyverno:generatecontroller
 5rules:
 6- apiGroups:
 7  - "*"
 8  resources:
 9  - namespaces
10  - networkpolicies
11  - secrets
12  - configmaps
13  - resourcequotas
14  - limitranges
15  - ResourceA # new Resource to be generated
16  - ResourceB
17  verbs:
18  - create # generate new resources
19  - get # check the contents of exiting resources
20  - update # update existing resource, if required configuration defined in policy is not present
21  - delete # clean-up, if the generate trigger resource is deleted

 1kind: ClusterRoleBinding
 2apiVersion: rbac.authorization.k8s.io/v1beta1
 3metadata:
 4  name: kyverno-admin-generate
 5roleRef:
 6  apiGroup: rbac.authorization.k8s.io
 7  kind: ClusterRole
 8  name: kyverno:generatecontroller # clusterRole defined above, to manage generated resources
 9subjects:
10- kind: ServiceAccount
11  name: kyverno-service-account # default kyverno serviceAccount
12  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.

1spec:
2  containers:
3    - name: kyverno
4      # image: ghcr.io/kyverno/kyverno:latest
5      image: ghcr.io/kyverno/kyverno:v1.3.0

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

Example:

1apiVersion: v1
2kind: Namespace
3metadata:
4  name: <namespace>

1apiVersion: v1
2kind: Service
3metadata:
4  labels:
5    app: kyverno
6  name: kyverno-svc
7  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:

1kubectl create -f ./install.yaml

To check the Kyverno controller status, run the command:

1kubectl get pods -n <namespace>

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

1kubectl describe pod <kyverno-pod-name> -n <namespace>

1kubectl 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. filterK8sResources(deprecated): 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, *, *]”.
4. gen-workers: the number of workers for processing generate policies concurrently. Default is set to 10.
5. background-scan: the interval (like 30s, 15m, 12h) for background processing. Default is set to 1h.
6. generateSuccessEvents: specifies whether (true/false) to generate success events. Default is set to “false”.

Policy Report access

During the Kyverno installation, it creates a ClusterRole kyverno:admin-policyreport which has permission to perform all operations on resources policyreport and clusterpolicyreport. 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

 1apiVersion: rbac.authorization.k8s.io/v1beta1
 2kind: RoleBinding
 3metadata:
 4  name: policyviolation
 5  # change namespace below to create rolebinding for the namespace admin
 6  namespace: default
 7roleRef:
 8  apiGroup: rbac.authorization.k8s.io
 9  kind: ClusterRole
10  name: kyverno:admin-policyreport
11subjects:
12# configure below to access policy violation for the namespace admin
13- kind: ServiceAccount
14  name: default
15  namespace: default
16# - apiGroup: rbac.authorization.k8s.io
17#   kind: User
18#   name:
19# - apiGroup: rbac.authorization.k8s.io
20#   kind: Group
21#   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 kyverno 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 kind Node in any namespace and with any name will be ignored. Wildcards are also supported in each of these sequences. For example, this sequence filters out kind Pod in namespace foo-system having names beginning with redis.

[Pod,foo-system,redis*]

By default a number of kinds are skipped in the default configuration including Nodes, Events, APIService, SubjectAccessReview, and more.

1apiVersion: v1
2kind: ConfigMap
3metadata:
4  name: kyverno
5  namespace: kyverno
6data:
7  # resource types to be skipped by kyverno policy engine
8  resourceFilters: '[Event,*,*][*,kube-system,*][*,kube-public,*][*,kube-node-lease,*][Node,*,*][APIService,*,*][TokenReview,*,*][SubjectAccessReview,*,*][SelfSubjectAccessReview,*,*][*,kyverno,*][Binding,*,*][ReplicaSet,*,*][ReportChangeRequest,*,*][ClusterReportChangeRequest,*,*]'

To modify the ConfigMap, either directly edit the ConfigMap kyverno 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.

Webhooks

By default, the Kyverno webhook will process all API server call-backs from all Namespaces. In some cases, it is desired to limit those to certain Namespaces based upon labels. Kyverno can filter on these Namespaces using a namespaceSelector object by adding a new webhooks object to the ConfigMap. For example, in the below snippet, the webhooks object has been added with a namespaceSelector object which will filter on Namespaces with the label environment=prod. The webhooks key only accepts as its value a JSON-formatted namespaceSelector object.

1apiVersion: v1
2data:
3  resourceFilters: '[Event,*,*][*,kube-system,*][*,kube-public,*][*,kube-node-lease,*][Node,*,*][APIService,*,*][TokenReview,*,*][SubjectAccessReview,*,*][SelfSubjectAccessReview,*,*][*,kyverno,*][Binding,*,*][ReplicaSet,*,*][ReportChangeRequest,*,*][ClusterReportChangeRequest,*,*]'
4  webhooks: '[{"namespaceSelector":{"matchExpressions":[{"key":"environment","operator":"In","values":["prod"]}]}}]'
5kind: ConfigMap
6metadata:
7  name: kyverno
8  namespace: kyverno

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.

1kubectl 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.

1helm 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.

1helm search repo kyverno

Run the upgrade command picking the target version.

1helm upgrade kyverno-crds kyverno/kyverno-crds --namespace kyverno --version <version_number>
2helm upgrade kyverno kyverno/kyverno --namespace kyverno --version <version_number>

Below are the steps to upgrade Kyverno to 1.4.2 from a version prior to 1.4.2. The upgrade to 1.4.2+ requires first removing the old CRDs and letting the Helm chart install the CRDs.

First take a backup of all cluster policies

1kubectl get clusterpolicy -A -o yaml > kyverno-policies.yaml

Perform the upgrade

1kubectl delete -f https://raw.githubusercontent.com/kyverno/kyverno/v1.4.2/charts/kyverno/crds/crds.yaml
2helm install kyverno-crds kyverno/kyverno-crds --namespace kyverno --version <version_number>
3helm upgrade kyverno kyverno/kyverno --namespace kyverno --version <version_number>

Restore Kyverno cluster policies

1kubectl apply -f kyverno-policies.yaml

Uninstalling Kyverno

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

Option 1 - Uninstall Kyverno with YAML manifest

1kubectl delete -f https://raw.githubusercontent.com/kyverno/kyverno/main/definitions/release/install.yaml

Option 2 - Uninstall Kyverno with Helm

1helm uninstall kyverno kyverno/kyverno --namespace kyverno
2helm uninstall kyverno-crds kyverno/kyverno-crds --namespace kyverno

Clean up Webhook Configurations

Kyverno by default will try to clean up all its webhook configurations when terminated. But in cases where its RBAC resources are removed first, it will lose the permission to do so properly.

Regardless which uninstallation method is chosen, webhooks will need to be manually removed as the final step. Use the below commands to delete those webhook configurations.

1kubectl delete mutatingwebhookconfigurations kyverno-policy-mutating-webhook-cfg kyverno-resource-mutating-webhook-cfg kyverno-verify-mutating-webhook-cfg
2
3kubectl delete validatingwebhookconfigurations kyverno-policy-validating-webhook-cfg kyverno-resource-validating-webhook-cfg