Working with Kyverno

Working with Kyverno

Kyverno, a Cloud Native Computing Foundation project, is a policy engine designed for Kubernetes. It can validate, mutate, and generate configurations using admission controls and background scans. Kyverno policies are Kubernetes resources and do not require learning a new language. Kyverno is designed to work nicely with tools you already use like kubectl, kustomize, and Git.

This document gives an example to demonstrate how to use Kyverno to manage policies across multiple clusters.

Setup Karmada

To start up Karmada, you can refer to here. If you just want to try Karmada, we recommend building a development environment by hack/local-up-karmada.sh.

git clone https://github.com/karmada-io/karmada
cd karmada
hack/local-up-karmada.sh

Kyverno Installations

In this case, we will use Kyverno v1.6.3. Related deployment files are from here.

note

You can choose the version of Kyverno based on that of the cluster where Karmada is installed. See details here. However, Kyverno 1.7.x removes the kubeconfig parameter and does not support out-of-cluster installations. So Kyverno 1.7.x is not able to run with Karmada.

Install Kyverno APIs on Karmada

Switch to Karmada control plane.

kubectl config use-context karmada-apiserver

Create resource objects of Kyverno in Karmada control plane. The content is as follows and does not need to be modified.

Deploy namespace: https://github.com/kyverno/kyverno/blob/release-1.6/config/install.yaml#L1-L12

Deploy configmap: https://github.com/kyverno/kyverno/blob/release-1.6/config/install.yaml#L7751-L7783

Deploy Kyverno CRDs: https://github.com/kyverno/kyverno/blob/release-1.6/config/install.yaml#L12-L7291

Install Kyverno components on host cluster

Switch to karmada-host context.

kubectl config use-context karmada-host

Create resource objects of Kyverno in karmada-host context, the content is as follows.

Deploy namespace: https://github.com/kyverno/kyverno/blob/release-1.6/config/install.yaml#L1-L12

Deploy RBAC resources: https://github.com/kyverno/kyverno/blob/release-1.6/config/install.yaml#L7292-L7750

Deploy Karmada kubeconfig in Kyverno namespace. Fill in the secret which represents kubeconfig pointing to karmada-apiserver, such as ca_crt, client_cer and client_key below.

apiVersion: v1
stringData:
   kubeconfig: |-
      apiVersion: v1
      clusters:
      - cluster:
          certificate-authority-data: {{ca_crt}}
          server: https://karmada-apiserver.karmada-system.svc.cluster.local:5443
        name: kind-karmada
      contexts:
      - context:
          cluster: kind-karmada
          user: kind-karmada
        name: karmada
      current-context: karmada
      kind: Config
      preferences: {}
      users:
      - name: kind-karmada
        user:
          client-certificate-data: {{client_cer}}
          client-key-data: {{client_key}}
kind: Secret
metadata:
   name: kubeconfig
   namespace: kyverno

Deploy Kyverno controllers and services:

apiVersion: v1
kind: Service
metadata:
   labels:
      app: kyverno
      app.kubernetes.io/component: kyverno
      app.kubernetes.io/instance: kyverno
      app.kubernetes.io/name: kyverno
      app.kubernetes.io/part-of: kyverno
      app.kubernetes.io/version: v1.6.3
   name: kyverno-svc
   namespace: kyverno
spec:
   type: NodePort
   ports:
      - name: https
        port: 443
        targetPort: https
        nodePort: {{nodePort}}
   selector:
      app: kyverno
      app.kubernetes.io/name: kyverno
---
apiVersion: v1
kind: Service
metadata:
   labels:
      app: kyverno
      app.kubernetes.io/component: kyverno
      app.kubernetes.io/instance: kyverno
      app.kubernetes.io/name: kyverno
      app.kubernetes.io/part-of: kyverno
      app.kubernetes.io/version: v1.6.3
   name: kyverno-svc-metrics
   namespace: kyverno
spec:
   ports:
      - name: metrics-port
        port: 8000
        targetPort: metrics-port
   selector:
      app: kyverno
      app.kubernetes.io/name: kyverno
---
apiVersion: apps/v1
kind: Deployment
metadata:
   labels:
      app: kyverno
      app.kubernetes.io/component: kyverno
      app.kubernetes.io/instance: kyverno
      app.kubernetes.io/name: kyverno
      app.kubernetes.io/part-of: kyverno
      app.kubernetes.io/version: v1.6.3
   name: kyverno
   namespace: kyverno
spec:
   replicas: 1
   selector:
      matchLabels:
         app: kyverno
         app.kubernetes.io/name: kyverno
   strategy:
      rollingUpdate:
         maxSurge: 1
         maxUnavailable: 40%
      type: RollingUpdate
   template:
      metadata:
         labels:
            app: kyverno
            app.kubernetes.io/component: kyverno
            app.kubernetes.io/instance: kyverno
            app.kubernetes.io/name: kyverno
            app.kubernetes.io/part-of: kyverno
            app.kubernetes.io/version: v1.6.3
      spec:
         affinity:
            podAntiAffinity:
               preferredDuringSchedulingIgnoredDuringExecution:
                  - podAffinityTerm:
                       labelSelector:
                          matchExpressions:
                             - key: app.kubernetes.io/name
                               operator: In
                               values:
                                  - kyverno
                       topologyKey: kubernetes.io/hostname
                    weight: 1
         containers:
            - args:
                 - --filterK8sResources=[Event,*,*][*,kube-system,*][*,kube-public,*][*,kube-node-lease,*][Node,*,*][APIService,*,*][TokenReview,*,*][SubjectAccessReview,*,*][*,kyverno,kyverno*][Binding,*,*][ReplicaSet,*,*][ReportChangeRequest,*,*][ClusterReportChangeRequest,*,*][PolicyReport,*,*][ClusterPolicyReport,*,*]
                 - -v=2
                 - --kubeconfig=/etc/kubeconfig
                 - --serverIP={{nodeIP}}:{{nodePort}}
              env:
                 - name: INIT_CONFIG
                   value: kyverno
                 - name: METRICS_CONFIG
                   value: kyverno-metrics
                 - name: KYVERNO_NAMESPACE
                   valueFrom:
                      fieldRef:
                         fieldPath: metadata.namespace
                 - name: KYVERNO_SVC
                   value: kyverno-svc
                 - name: TUF_ROOT
                   value: /.sigstore
              image: ghcr.io/kyverno/kyverno:v1.6.3
              imagePullPolicy: Always
              livenessProbe:
                 failureThreshold: 2
                 httpGet:
                    path: /health/liveness
                    port: 9443
                    scheme: HTTPS
                 initialDelaySeconds: 15
                 periodSeconds: 30
                 successThreshold: 1
                 timeoutSeconds: 5
              name: kyverno
              ports:
                 - containerPort: 9443
                   name: https
                   protocol: TCP
                 - containerPort: 8000
                   name: metrics-port
                   protocol: TCP
              readinessProbe:
                 failureThreshold: 4
                 httpGet:
                    path: /health/readiness
                    port: 9443
                    scheme: HTTPS
                 initialDelaySeconds: 5
                 periodSeconds: 10
                 successThreshold: 1
                 timeoutSeconds: 5
              resources:
                 limits:
                    memory: 384Mi
                 requests:
                    cpu: 100m
                    memory: 128Mi
              securityContext:
                 allowPrivilegeEscalation: false
                 capabilities:
                    drop:
                       - ALL
                 privileged: false
                 readOnlyRootFilesystem: true
                 runAsNonRoot: true
              volumeMounts:
                 - mountPath: /.sigstore
                   name: sigstore
                 - mountPath: /etc/kubeconfig
                   name: kubeconfig
                   subPath: kubeconfig
         initContainers:
            - env:
                 - name: METRICS_CONFIG
                   value: kyverno-metrics
                 - name: KYVERNO_NAMESPACE
                   valueFrom:
                      fieldRef:
                         fieldPath: metadata.namespace
              image: ghcr.io/kyverno/kyvernopre:v1.6.3
              imagePullPolicy: Always
              name: kyverno-pre
              resources:
                 limits:
                    cpu: 100m
                    memory: 256Mi
                 requests:
                    cpu: 10m
                    memory: 64Mi
              securityContext:
                 allowPrivilegeEscalation: false
                 capabilities:
                    drop:
                       - ALL
                 privileged: false
                 readOnlyRootFilesystem: true
                 runAsNonRoot: true
         securityContext:
            runAsNonRoot: true
         serviceAccountName: kyverno-service-account
         volumes:
            - emptyDir: {}
              name: sigstore
            - name: kubeconfig
              secret:
                 defaultMode: 420
                 secretName: kubeconfig
---

For multi-cluster deployment, we need to add the config of --serverIP which is the address of the webhook server. So you need to ensure that the network from nodes in Karmada control plane to those in karmada-host cluster is connected and expose Kyverno controller pods to control plane, for example, using nodePort above.

Run demo

Create require-labels ClusterPolicy

ClusterPolicy is a CRD which Kyverno offers to support different kinds of rules. Here is an example ClusterPolicy which means that you must create pod with app.kubernetes.io/name label. You can use the following commands to create it in Karmada control plane.

kubectl config use-context karmada-apiserver

kubectl create -f- << EOF
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: require-labels
spec:
  validationFailureAction: enforce
  rules:
  - name: check-for-labels
    match:
      any:
      - resources:
          kinds:
          - Pod
    validate:
      message: "label 'app.kubernetes.io/name' is required"
      pattern:
        metadata:
          labels:
            app.kubernetes.io/name: "?*"
EOF

The output is similar to:

clusterpolicy.kyverno.io/require-labels created

Create a bad deployment without labels

kubectl create deployment nginx --image=nginx

The output is similar to:

error: failed to create deployment: admission webhook "validate.kyverno.svc-fail" denied the request: 
policy Deployment/default/nginx for resource violation: 
require-labels:
  autogen-check-for-labels: 'validation error: label ''app.kubernetes.io/name'' is
    required. rule autogen-check-for-labels failed at path /spec/template/metadata/labels/app.kubernetes.io/name/'

Reference

https://github.com/kyverno/kyverno