Day 14: Securing Kubernetes – Runtime Security and Policy Enforcement

Welcome to Day 14 of the Zero to Platform Engineer in 30 Days challenge! 🚀 Today, we’ll focus on securing Kubernetes clusters, covering runtime security and policy enforcement to ensure your applications and infrastructure are protected from vulnerabilities and misconfigurations.

Why Kubernetes Security Matters?

Kubernetes security is critical to:

Prevent unauthorized access to sensitive data and applications.
Detect and respond to runtime threats.
Ensure compliance with security and governance policies.

🎯 Key Security Concepts:

Runtime Security: Detect and respond to suspicious behavior in running workloads.
Policy Enforcement: Apply guardrails to prevent risky configurations.

What Are Falco and OPA?

Falco

Purpose: Runtime security monitoring.
How It Works: Detects unexpected behavior (e.g., file changes, unauthorized process execution) in Kubernetes clusters.
Key Features:

Monitors workloads in real-time.
Generates alerts for anomalous behavior.

Open Policy Agent (OPA):

Purpose: Policy enforcement.
How It Works: Uses policies written in Rego to evaluate requests and enforce rules in Kubernetes.
Key Features:

Applies guardrails for configurations (e.g., restricting resource requests/limits).
Ensures compliance with security policies.

Hands-On: Securing Kubernetes

Step 1: Install Falco

Add the Helm repository for Falco:

helm repo add falcosecurity https://falcosecurity.github.io/charts
helm repo update

```
 Install Falco in your cluster:
```

helm install falco falcosecurity/falco --namespace falco --create-namespace

3 . Verify that Falco is installed:

kubectl get pods -n falco

4 . View Falco alerts:

kubectl logs -l app=falco -n falco

Step 2: Configure OPA for Policy Enforcement

Add the Gatekeeper Helm chart (OPA Kubernetes extension):

helm repo add gatekeeper https://open-policy-agent.github.io/gatekeeper/charts
helm repo update

Install Gatekeeper in your cluster:

helm install gatekeeper gatekeeper/gatekeeper --namespace gatekeeper-system --create-namespace

Create a sample policy to enforce resource limits:

apiVersion: templates.gatekeeper.sh/v1
kind: ConstraintTemplate
metadata:
  name: k8sresourcelimits
spec:
  crd:
    spec:
      names:
        kind: K8sResourceLimits
  targets:
  - target: admission.k8s.gatekeeper.sh
    rego: |
      package k8sresourcelimits
      deny[msg] {
        input.review.object.spec.containers[_].resources.limits.cpu == ""
        msg := "CPU limits must be set"
      }

4 . Apply the policy:

kubectl apply -f policy.yaml

Test the policy by deploying a Pod without CPU limits and observing the denial.

Step 3: Monitor and Respond to Security Incidents

Simulate a runtime security event (e.g., modifying a critical file inside a container) and observe Falco alerts.
Test policy enforcement with OPA by deploying a misconfigured resource and viewing the rejection.

Activity for Today

Install Falco and configure runtime security monitoring.
Set up OPA/Gatekeeper to enforce a policy for Kubernetes configurations.
Simulate a runtime threat and test policy violations to observe how your security systems respond.

What’s Next?

Now that you’ve secured your Kubernetes clusters, tomorrow we’ll explore automating Kubernetes workflows with tools like Kustomize and Skaffold.

Get ready to level up your platform engineering skills! 🚀

👉 Check it out here: Zero to Platform Engineer Repository

Feel free to clone the repo, experiment with the code, and even contribute if you’d like! 🚀

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