Kubernetes Manifest Quality Review

Kubernetes Manifest Quality Review

Purpose

This skill reviews raw Kubernetes YAML manifests for quality, security, and policy-compliance defects. It covers Deployment, StatefulSet, DaemonSet, Service, Ingress, NetworkPolicy, RBAC, and CRD resources. The review is entirely static — it reads YAML files and never applies manifests to a cluster, never contacts the Kubernetes API, and never requests kubeconfig, service account tokens, or cloud credentials.

Lean operating rules

Schema and structure

• apiVersion or kind missing — CRITICAL: the manifest cannot be applied; flag and stop review of that resource.
• Deprecated API versions (e.g., extensions/v1beta1, networking.k8s.io/v1beta1, policy/v1beta1 PodSecurityPolicy) — HIGH: these will be rejected by newer clusters.
• Missing required labels (app, app.kubernetes.io/name, app.kubernetes.io/version) on Pods and workload controllers — MEDIUM: impairs observability, selector targeting, and policy enforcement.
• No namespace specified (reliance on default namespace) — MEDIUM: encourages lateral movement and policy bypass; everything should be explicitly namespaced.

Pod security (Pod Security Standards)

• securityContext.runAsRoot: true on a container, or no runAsNonRoot: true at pod or container level — HIGH: processes run as UID 0 inside the container.
• privileged: true on a container security context — CRITICAL: the container has near-host-root access.
• allowPrivilegeEscalation: true or field absent (it defaults to true unless privileged: false is set) — HIGH: child processes can gain more privileges than the parent.
• hostNetwork: true, hostPID: true, hostIPC: true on the pod spec — CRITICAL: the pod shares the host network stack, process table, or IPC namespace, enabling broad host compromise.
• capabilities.add containing SYS_ADMIN, NET_ADMIN, ALL, SYS_PTRACE, or DAC_OVERRIDE — CRITICAL: these capabilities provide near-root privilege; drop all capabilities and add only what is specifically required.
• readOnlyRootFilesystem: false or field absent on a container — MEDIUM: a writable root filesystem makes container compromise easier; set to true and use emptyDir or volume mounts for mutable paths.
• seccompProfile absent at pod or container level — MEDIUM: no syscall filtering, increasing the kernel attack surface; use RuntimeDefault or a custom profile.

Image hygiene

• Image tag is :latest or absent — HIGH: non-reproducible deployments; a rollout can silently pull a different image than what was tested.
• No image digest pinning for production manifests — MEDIUM: tag mutability allows supply-chain substitution; prefer image@sha256:<digest>.
• Image pulled from an unverified public registry (e.g., Docker Hub) with no imagePullPolicy: IfNotPresent or digest — MEDIUM: arbitrary public images without integrity verification.

Resource governance

• resources.requests and resources.limits both absent on a container — HIGH: the container is unschedulable on resource-constrained nodes and can starve co-located workloads.
• Memory limit set without a CPU limit — MEDIUM: CPU throttling surprise; the container can be throttled heavily with no visible error.
• Ephemeral storage limit absent on containers known to produce logs or temp files — LOW: unbounded ephemeral storage can exhaust node disk and evict other pods.

Health probes

• livenessProbe missing — HIGH: the kubelet cannot detect application deadlocks or crash-loop conditions and restart the container.
• readinessProbe missing — HIGH: the endpoint controller sends traffic to the pod before the application is ready, causing errors during startup and rolling updates.
• Probe using exec command with no timeoutSeconds specified — MEDIUM: exec probes default to a 1-second timeout; a slow command silently causes probe failures and restarts.

Networking and exposure

• Service type LoadBalancer or NodePort without a comment or annotation documenting the business justification — MEDIUM: these expose services externally or on every node port; ClusterIP is sufficient for internal services.
• Ingress resource with no TLS block configured — HIGH: traffic between the client and the ingress controller is unencrypted.
• No NetworkPolicy resource restricts pod ingress or egress in the namespace — MEDIUM: the default Kubernetes network model is allow-all; without a NetworkPolicy every pod can reach every other pod.
• Ingress annotation nginx.ingress.kubernetes.io/use-proxy-protocol or similar annotation that forwards arbitrary upstream headers into backend requests from untrusted input — CRITICAL: enables SSRF and header injection.

RBAC and service accounts

• ClusterRole with verb * on resource * or on secrets — CRITICAL: any principal bound to this role has full cluster read/write access.
• RoleBinding or ClusterRoleBinding whose subject is system:anonymous or system:unauthenticated — CRITICAL: unauthenticated callers inherit these permissions.
• automountServiceAccountToken: true (or field absent, which defaults to true) on pods that do not contact the Kubernetes API — HIGH: the token is mounted at a known path and exploitable if the container is compromised.
• RBAC role granting get or list on secrets beyond what the workload demonstrably needs — HIGH: broadens blast radius of a credential compromise.

Secrets and config

• Plaintext credentials (passwords, tokens, connection strings) in env.value on a container or in ConfigMap.data — CRITICAL: credentials visible in manifests committed to source control or stored in etcd in plaintext.
• Secret with type: Opaque and a base64-encoded value that decodes to an empty string — MEDIUM: placeholder secret that will cause application startup failures and suggests secrets management is not wired up.

References

Load these only when needed:

• Workflow and output contract — use when executing the full review or formatting the final answer.

Response minimum

Return, at minimum:

• Schema and API version findings
• Pod security findings (PSS Restricted/Baseline comparison)
• Image hygiene findings
• Resource governance findings
• Health probe findings
• Networking and exposure findings
• RBAC and service account findings
• Secrets and config findings
• Severity-labelled finding list (CRITICAL / HIGH / MEDIUM / LOW)
• Safe next actions