Senior LevelCloud Computing (AWS/GCP/Azure)
How do you enforce Supply Chain Security in Kubernetes using Sigstore Cosign and Kyverno policy enforcement?
❓ Interview Prompt: Explain Container Software Supply Chain Security, Sigstore Cosign image signing, OIDC keyless signing, and Kyverno admission controller verification.
Preventing unauthorized or malicious container images from deploying into production Kubernetes clusters requires Software Supply Chain Verification.
Security Pipeline Mechanics:
1
CI/CD Build & Sign (Sigstore Cosign): During container build, Cosign signs the Docker image digest using OIDC keyless signing (Fulcio CA + Rekor transparency log).
2
Kubernetes Admission Control (Kyverno / OPA Gatekeeper):
•
A Kyverno Admission Controller intercepts every 'kubectl apply' pod deployment request.
•
Verifies the cryptographic Cosign signature against trusted public keys before permitting pod scheduling!
•
Rejects unsigned or tampered container images automatically.
Code Implementation Example
yaml
# Kyverno Policy verifying Sigstore Cosign container image signatures
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: verify-image-signature
spec:
validationFailureAction: Enforce # Block non-compliant pod deployments!
rules:
- name: verify-signature
match:
any:
- resources:
kinds: ["Pod"]
verifyImages:
- imageReferences: ["gcr.io/company/*"]
attestors:
- entries:
- keys:
publickeys: |
-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE...
-----END PUBLIC KEY-----💡Kyverno ClusterPolicy verifying Cosign digital signatures on container images.
🎯 Interview Key Takeaway
Enforce container supply chain security by signing images with Sigstore Cosign and verifying signatures via Kyverno admission controllers.
#Supply Chain Security#Cosign#Kyverno#Kubernetes Security#Senior
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