Q: How can Kyverno be used to strengthen Kubernetes security policies and enforce container validation, signing, and least-privilege mutation?
Production guide to implementing declarative admission control in Kubernetes using Kyverno to enforce Pod Security Standards (Restricted), verify Cosign container signatures, and mutate resource metadata.
#Kyverno #Kubernetes #Security #Admission Control #DevSecOps
🎙️ Candidate Opening & Architectural Context
"Kyverno is a Kubernetes-native policy engine that operates as a dynamic admission controller. Unlike OPA Gatekeeper, which requires writing complex Rego code, Kyverno policies are written in standard Kubernetes YAML to validate, mutate, and generate cluster resources."
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🛠️ Production Runbook & Step-by-Step Resolution
1
Enforce Disallow Root Containers (Pod Security Standards)
Apply a ClusterPolicy that validates pods must set runAsNonRoot: true and drop all Linux capabilities.
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: disallow-root-execution
spec:
validationFailureAction: Enforce
rules:
- name: check-runAsNonRoot
match:
resources:
kinds: ["Pod"]
validate:
message: "Containers must run as non-root!"
pattern:
spec:
securityContext:
runAsNonRoot: true
2
Verify Signed Container Images (Cosign Integration)
Kyverno natively integrates with Sigstore/Cosign. It checks cryptographic signatures and attestations directly during admission before any image is allowed to pull from registries.
3
Auto-Mutate Pod Annotations & Default Labels
Kyverno can automatically mutate incoming manifests to inject required enterprise labels (cost-center, owner) or link imagePullSecrets.
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Kyverno delivers declarative K8s security policies in pure YAML without Rego. Use it to enforce non-root execution, verify Cosign signatures, and auto-inject required metadata."
⚡ 60-Second Elevator Pitch Talking Points
- Kyverno operates as a Kubernetes admission webhook written in standard YAML (no Rego required).
- Validate: enforce Pod Security Standards (Restricted profile, drop capabilities, read-only root FS).
- Verify Images: integrate with Sigstore/Cosign to block unsigned or unverified container images.
- Mutate & Generate: auto-inject standard labels, network policies, and security contexts.
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