Kyverno 101: Understanding Kubernetes Policy Enforcement with Kyverno

Setting up rules and policies around resources in your Kubernetes cluster ensures a stable environment that follows organizational best practices. Kyverno, a Kubernetes-native policy engine, allows you to define and enforce policies using YAML, acting as a gatekeeper to maintain expected resource states.

Read the full article here: Part 2: Kyverno 101 — Understanding Kyverno Policies

You Should Know:

1. Installing Kyverno

To deploy Kyverno in your Kubernetes cluster, use Helm:

helm repo add kyverno https://kyverno.github.io/kyverno/ 
helm repo update 
helm install kyverno kyverno/kyverno -n kyverno --create-namespace 

2. Creating a Basic Policy

Kyverno policies are defined in YAML. Below is an example policy that enforces resource limits on Pods:

apiVersion: kyverno.io/v1 
kind: ClusterPolicy 
metadata: 
name: require-resource-limits 
spec: 
validationFailureAction: enforce 
rules: 
- name: validate-resource-limits 
match: 
resources: 
kinds: 
- Pod 
validate: 
message: "CPU and memory limits are required." 
pattern: 
spec: 
containers: 
- resources: 
limits: 
memory: "?" 
cpu: "?" 

3. Applying Policies

Save the policy as `policy.yaml` and apply it:

kubectl apply -f policy.yaml 

4. Testing Enforcement

Try creating a Pod without resource limits to see Kyverno block it:

apiVersion: v1 
kind: Pod 
metadata: 
name: test-pod 
spec: 
containers: 
- name: nginx 
image: nginx 

Apply and observe the rejection:

kubectl apply -f test-pod.yaml 

5. Auditing Existing Resources

Check non-compliant resources with:

kubectl get policyreport -A 

6. Advanced Policy: Block Latest Tags

Prevent using `:latest` tags in images:

apiVersion: kyverno.io/v1 
kind: ClusterPolicy 
metadata: 
name: block-latest-tag 
spec: 
validationFailureAction: enforce 
rules: 
- name: block-latest-tag 
match: 
resources: 
kinds: 
- Pod 
validate: 
message: "Using ':latest' tag is not allowed." 
pattern: 
spec: 
containers: 
- image: "!:latest" 

7. Automating Policy Checks in CI/CD

Integrate Kyverno CLI in pipelines:

kyverno apply ./policies --resource=./manifests 

What Undercode Say

Kyverno provides a robust way to enforce Kubernetes best practices, reducing misconfigurations and security risks. By leveraging policies, teams can automate compliance checks, ensuring only validated configurations are deployed. Future enhancements may include AI-driven policy suggestions and deeper integration with GitOps workflows.

Expected Output:

ClusterPolicy/require-resource-limits created 
Error from server: admission webhook "validate.kyverno.svc" denied the request: resource Pod/default/test-pod was blocked due to Policy require-resource-limits 

Prediction

As Kubernetes adoption grows, policy enforcement tools like Kyverno will become essential for governance, with tighter integration in DevSecOps pipelines and automated remediation features.

IT/Security Reporter URL:

Reported By: Darryl Ruggles – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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