Kubernetes Manifest Audit

Kubernetes Manifest Audit

ultrathink

Output path directive (canonical — overrides in-body references). All file outputs from this skill MUST be written under .anthril/audits/kubernetes-manifest-audit/. Run mkdir -p .anthril/audits/kubernetes-manifest-audit before the first Write call. Primary artefact: .anthril/audits/kubernetes-manifest-audit/<artefact>. Do NOT write to the project root or to bare filenames at cwd. Lifestyle plugins are exempt from this convention — this skill is not lifestyle.

When to use

Run this skill when the user mentions:

• Kubernetes audit, k8s security
• CIS Kubernetes Benchmark
• Helm chart review, Kustomize review
• Pod security standards
• NSA/CISA Kubernetes Hardening Guide

Covers nine categories: pod security (runAsNonRoot, readOnlyRootFilesystem, allowPrivilegeEscalation, dropped capabilities, no host namespaces), resource requests and limits, liveness/readiness/startup probes, image hygiene (digest pinning, pull policy, scoped imagePullSecrets), secrets and config (no plaintext Secrets in Git, external secret operators), networking (NetworkPolicies, Service types, Ingress TLS), RBAC (per-workload ServiceAccounts, no wildcard verbs), availability (PodDisruptionBudgets, replicas, topology spread, anti-affinity), and Helm hygiene (values.schema.json, sensible defaults).

Before You Start

1. Determine operating mode. --live reads from a real cluster via kubectl, runs kube-bench and kube-hunter if installed. --apply produces YAML patches or kubectl patch commands (cluster changes require an explicit second confirmation). --runtime runs a scoped chaos experiment against non-prod (chaos-mesh or a simple pod-kill) if configured.
2. Enumerate manifest groups. Run scripts/list-manifests.sh.
3. Sub-agent budget. One agent per chart / Kustomize overlay / manifest directory. Warn above 10.
4. Load .k8s-ignore for suppressions.
5. Production-name guard. In --apply or --runtime, refuse targets whose namespace or context contains prod/production without --i-really-mean-prod.

User Context

$ARGUMENTS

Manifest inventory: !bash "${CLAUDE_PLUGIN_ROOT}/skills/kubernetes-manifest-audit/scripts/list-manifests.sh"

Live-mode tools: !which kubectl 2>/dev/null || echo "kubectl:unavailable" · !which helm 2>/dev/null || echo "helm:unavailable" · !which kube-bench 2>/dev/null || echo "kube-bench:unavailable"

Audit Phases

Phase 1: Discovery & Mode Selection

1. Parse inventory. Group manifests into audit units: one per Helm chart, one per Kustomize overlay, one per directory of raw manifests.
2. In --live mode, verify kubectl context is set and non-prod (or --i-really-mean-prod is present).
3. Confirm scope with the user; warn if >10 groups.

Phase 2: Per-Group Snapshot

For each group, extract every manifest's kind and relevant fields:

• Deployments, StatefulSets, DaemonSets, Jobs, CronJobs — spec.template.spec (containers, securityContext, resources, probes, volumes), replicas, strategy
• Services, Ingresses — type, ports, TLS
• ConfigMaps, Secrets — data keys (never values), sealing status
• RBAC — ServiceAccounts, Roles/ClusterRoles, Bindings
• NetworkPolicies — selectors, ingress/egress rules
• PDBs, HPAs — target workloads and thresholds
• Helm-specific: Chart.yaml, values.yaml, values.schema.json, templates/

In --live mode, cross-reference with kubectl get output per namespace.

Phase 3: Parallel Sub-Agent Audit

Spawn one Agent(subagent_type=Explore) per group (single assistant message). Each walks categories A–I from reference.md §1.

• A. Pod security — runAsNonRoot, readOnlyRootFilesystem, allowPrivilegeEscalation: false, dropped capabilities, no hostNetwork/hostPID/hostIPC, seccomp profile
• B. Resources — every container has requests + limits for cpu and memory; QoS tier appropriate
• C. Probes — liveness, readiness, startup configured; thresholds sensible
• D. Image hygiene — digest-pinned, imagePullPolicy: IfNotPresent (not Always in prod), imagePullSecrets scoped
• E. Secrets & config — no plaintext Secret YAML in Git (SealedSecrets / External Secrets / SOPS acceptable); ConfigMap not misused for secrets
• F. Networking — NetworkPolicy present for each workload namespace; Service type sensible; Ingress TLS
• G. RBAC — per-workload ServiceAccount; no wildcard verbs: ["*"] or resources: ["*"]
• H. Availability — PDB for critical workloads; replicas > 1 for prod; topology spread or anti-affinity; rolling update surge/unavailable bounds
• I. Helm hygiene — values.schema.json, templated fields have defaults, no hardcoded production values in values.yaml

Sub-agents may read kubectl get <kind> -o yaml in --live mode but MUST NOT run kubectl apply, kubectl delete, kubectl patch, helm install, or helm upgrade.

Phase 4: Merge & Risk Register

Merge sub-agent output. Cross-reference with kube-bench output if available (attach matching CIS IDs to findings). Assign K8S-001… IDs.

Phase 5: Remediation Drafting

Emit commented YAML to k8s-suggested.yaml. Each block shows the target file:line, the evidence, and the fix.

For --live mode, alternatives as kubectl patch commands are included — but commented out, never executed.

Phase 6: Apply Mode (opt-in)

Interactive [a]pply / [s]kip / [A]ll / [q]uit loop. YAML file edits go through Edit. kubectl patch execution requires the literal word DESTROY confirmation and writes both the patch command and the prior state to apply-log.md.

Phase 7: Runtime Testing (opt-in)

When --runtime and a non-prod cluster is confirmed:

1. Identify the target Deployment (user-selected; defaults to the most-replicated non-system one).
2. Run a scoped chaos experiment: single pod deletion, confirm rolling recovery within its progressDeadlineSeconds.
3. Alternative: run kubectl drain on one node if --chaos-node flag is passed.
4. Record metrics from kubectl top pods pre/post if metrics-server is available.
5. Attach results to the report as "Runtime resilience test".

Phase 8: Reporting

Write kubernetes-manifest-audit.md + kubernetes-manifest-audit.json + k8s-suggested.yaml (+ cluster-state.json in --live mode and chaos-run.md in --runtime).

Scoring

Weights: A=20, B=15, C=10, D=10, E=15, F=10, G=10, H=5, I=5 (sum 100). See reference.md §3.

Important Principles

• Default security is insecure. A Deployment with no securityContext runs as root with full capabilities. This is always at least HIGH.
• No requests = best-effort QoS. The first pod to be evicted under memory pressure. Flag every container missing requests.
• Secrets in plaintext YAML belong outside Git. SealedSecrets / External Secrets Operator / SOPS / cluster-managed Secrets are all acceptable alternatives.
• Ingress without TLS is HIGH severity on prod. Often downgraded to MEDIUM on internal-only ingress, but still flagged.
• replicas: 1 in prod is MEDIUM-HIGH. A single pod is a single point of failure.
• Helm's values.yaml is often production values. Treat it as a manifest — it deploys real things.
• Runtime chaos is non-prod only. Never run a chaos experiment against a cluster whose context/namespace contains prod/production without --i-really-mean-prod.
• Australian English. DD/MM/YYYY. Markdown-first.

Edge Cases

1. Pure Helm chart (no rendered manifests in Git). Run helm template to render, then audit the rendered output.
2. Operator-managed CRDs. Audit the CR spec; note that operator semantics may enforce additional rules outside this skill's view.
3. GitOps repo (Argo CD / Flux). Audit source manifests; in --live mode, note the sync state but do not edit.
4. Cluster-scoped resources (ClusterRoles, ClusterRoleBindings). Weight RBAC findings higher; cluster-wide scope amplifies blast radius.
5. Mutating admission webhooks in cluster. Rendered manifests may differ from deployed. In --live mode, cross-check.
6. DaemonSets often need host namespaces. CNI plugins, log shippers — flag but allow suppression.
7. Jobs and CronJobs — probes don't apply; resource requests still do.
8. NetworkPolicy absence — if the CNI doesn't enforce NetworkPolicy, skip F findings for that group (note in report).

Source: anthril/official-claude-plugins — distributed by TomeVault.