Kubernetes Policy as Code with Kyverno - Enforcing Best Practices the Native Way
Managing security and compliance in Kubernetes clusters can be challenging, especially when dealing with multiple teams and environments. Manual policy enforcement is error-prone and doesn’t scale. This is where Kyverno comes in - a Kubernetes-native policy engine that helps you enforce best practices automatically using simple YAML policies.
In this guide, we’ll walk through setting up Kyverno and implementing essential policies that every Kubernetes cluster should have.
What is Kyverno?
Kyverno is a policy engine designed for Kubernetes that allows you to:
- Validate resources against security and operational standards
- Mutate resources to automatically apply best practices
- Generate additional resources like NetworkPolicies automatically
- Clean up resources based on conditions
Unlike other policy engines, Kyverno uses YAML instead of domain-specific languages, making it accessible to any Kubernetes user.
How Kyverno Works
Kyverno operates as a Kubernetes admission controller, intercepting API requests before resources are created or modified in your cluster. Here’s the flow:
- User creates a Kubernetes resource (Pod, Deployment, etc.)
- Kubernetes API server sends the request to Kyverno
- Kyverno evaluates the resource against defined policies
- Based on policy rules, Kyverno allows, denies, or modifies the resource
- The final resource is created in the cluster
Installing Kyverno
The easiest way to install Kyverno is using Helm:
1 | # Add Kyverno Helm repository |
Verify the installation:
1 | kubectl get pods -n kyverno |
You should see the Kyverno pods running successfully.
Basic Policy Examples
Let’s start with practical policies that solve real-world problems.
1. Require Resource Limits (Validation Policy)
This policy ensures all containers have resource requests and limits defined:
1 | apiVersion: kyverno.io/v1 |
Apply this policy:
1 | kubectl apply -f require-resources-policy.yaml |
Now try creating a pod without resource limits:
1 | apiVersion: v1 |
This will be rejected with the message “Resource requests and limits are required”.
2. Add Default Labels (Mutation Policy)
This policy automatically adds standard labels to all resources:
1 | apiVersion: kyverno.io/v1 |
With this policy, any new resource will automatically get these labels added.
3. Disallow Privileged Containers (Validation Policy)
Security policy to prevent privileged containers:
1 | apiVersion: kyverno.io/v1 |
4. Generate Default NetworkPolicy (Generation Policy)
Automatically create a default-deny NetworkPolicy for new namespaces:
1 | apiVersion: kyverno.io/v1 |
Testing Your Policies
Test with Valid Resources
Create a pod that complies with your policies:
1 | apiVersion: v1 |
This pod should be created successfully and will have the default labels added automatically.
View Policy Reports
Check policy violations and compliance:
1 | # View cluster policy reports |
Common Use Cases
Enforce Security Standards
1 | apiVersion: kyverno.io/v1 |
Standardize Resource Naming
1 | apiVersion: kyverno.io/v1 |
Best Practices
Start with Audit Mode: Before enforcing policies, run them in audit mode to see their impact:
1 | spec: |
Test Policies: Always test policies in development environments before production.
Use Background Scanning: Enable background scanning to check existing resources:
1 | spec: |
Monitor Policy Performance: Keep policies simple and efficient to avoid impacting cluster performance.
Troubleshooting
Policy Not Working
Check if the policy is correctly applied:
1 | kubectl get cpol |
View Kyverno Logs
1 | kubectl logs -n kyverno deployment/kyverno-admission-controller |
Webhook Issues
Ensure webhooks are properly configured:
1 | kubectl get validatingadmissionpolicies |
Conclusion
Kyverno makes implementing Kubernetes best practices straightforward and automated. By using familiar YAML syntax, teams can quickly create policies that:
- Enhance security by preventing misconfigurations
- Standardize resource configurations across teams
- Automate compliance and governance tasks
- Reduce operational overhead
Start with basic validation policies, test them thoroughly, then gradually add more sophisticated mutation and generation policies as your team becomes comfortable with Kyverno.
The key to success with Kyverno is starting simple and iterating. Begin with one or two essential policies, validate their impact, and expand from there. Your Kubernetes clusters will be more secure, compliant, and easier to manage.
You can find the all the related scripts for this tutorial from here.