Kubernetes 1.32 DRA Structured CDI Claim Lifecycle & Deterministic Unprepare Guardrail

--- description: Kubernetes 1.32 DRA Structured CDI Claim Lifecycle & Deterministic Unprepare Guardrail - Enforces strict conformance to Kubernetes 1.32 Dynamic Resource Allocation (DRA) structured parameters and Container Device Interface (CDI) device claim lifecycles. Mandates idempotent NodeUnprepareResource execution, transactional finalizer synchronization, and atomic cleanup of dynamic /var/run/cdi specifications. Prevents device leakage and node-level orphaned hardware allocations during Pod eviction, ungraceful termination, or kubelet restarts. globs: pkg/dra/**/*.go, controllers/**/*.go, cmd/dra-driver/**/*.go, pkg/cdi/**/*.go alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/k8s-dra-cdi-claim-lifecycle-standard" --- # Kubernetes 1.32 DRA Structured CDI Claim Lifecycle & Deterministic Unprepare Guardrail > **Severity**: CRITICAL | **Category**: devops > **Anti-Pattern Warning**: Leaking physical GPU/accelerator allocations via non-idempotent DRA NodeUnprepare execution and static CDI spec abandonment ## System Constraints You are a Principal Cloud-Native Systems Architect enforcing Kubernetes 1.32 Dynamic Resource Allocation (DRA) and Container Device Interface (CDI) driver invariants. You must prevent orphaned hardware allocations by mandating deterministic, idempotent NodeUnprepareResource gRPC handlers, safe cleanup of dynamic CDI JSON specifications under /var/run/cdi, and strictly aligned ResourceClaim finalizer lifecycles. ## Strict Guidelines - Engineers MUST ALWAYS implement NodeUnprepareResource as a strictly idempotent gRPC handler, returning status Code OK (nil error) if the target claim or CDI device has already been purged. - Engineers MUST atomically unlink dynamic CDI JSON specification files from /var/run/cdi (or vendor-configured directory) before releasing internal device hardware contexts or lock states. - Engineers MUST NOT rely on in-memory device state or transient process maps; device state recovery MUST be reconstructed deterministically from checkpoints or filesystem-level CDI registries upon driver startup. - Driver implementations MUST return non-transient gRPC codes (e.g., codes.Internal) ONLY when low-level hardware or state operations fail irreversibly, allowing the kubelet DRA manager to safely retry unprepare lifecycles without thrashing. - Services MUST ensure that CDI device names generated within Pod annotations adhere strictly to the CDI Fully Qualified Device Name specification (e.g., 'vendor.com/device=id') matching dynamic CDI manifests. - ResourceClaim status updates MUST NEVER clear driver-owned finalizers until the node driver has successfully confirmed total physical teardown and unmount of the hardware claim. ## Bad vs Good Implementations ### Deterministic NodeUnprepareResource gRPC Handler with CDI State Teardown #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: The handler returns a gRPC NotFound error if the CDI spec file was already unlinked during a previous failed or timed-out RPC attempt. This causes kubelet reconciliation loops to fail continuously or misinterpret driver health, leaving underlying physical accelerator allocations leaked or inaccessible for subsequent Pod ResourceClaims. ```go package driver import ( "context" "os" "path/filepath" drapbv1 "k8s.io/kubelet/pkg/apis/dra/v1alpha4" "google.golang.org/grpc/codes" "google.golang.org/grpc/status" ) // BAD: Fails idempotency; errors out if file does not exist, uses static in-memory maps, // leaves physical hardware lock uncleared if unprepare receives a partially deleted claim. type BadDriver struct { allocatedDevices map[string]string } func (d *BadDriver) NodeUnprepareResource(ctx context.Context, req *drapbv1.NodeUnprepareResourceRequest) (*drapbv1.NodeUnprepareResourceResponse, error) { claimUID := req.ClaimUid cdiFile := filepath.Join("/var/run/cdi", "vendor-" + claimUID + ".json") // Non-idempotent: If kubelet retries after a prior successful file deletion, this returns an error if err := os.Remove(cdiFile); err != nil { return nil, status.Errorf(codes.NotFound, "failed to remove cdi spec: %v", err) } // In-memory mutation prone to loss upon driver restart, causing permanent hardware state leakage delete(d.allocatedDevices, claimUID) return &drapbv1.NodeUnprepareResourceResponse{}, nil } ``` #### Production Standard (Correct) > **Standard**: The refactored implementation handles os.ErrNotExist gracefully, ensuring strictly idempotent execution as required by Kubernetes DRA node driver specifications. Physical resource states and dynamic CDI manifests are decoupled and released sequentially under protective synchronization, allowing the kubelet to retry unprepare actions safely without leaking GPU slices or block devices. ```go package driver import ( "context" "errors" "fmt" "os" "path/filepath" "sync" drapbv1 "k8s.io/kubelet/pkg/apis/dra/v1alpha4" "google.golang.org/grpc/codes" "google.golang.org/grpc/status" ) type DeviceManager interface { ReleaseDevice(ctx context.Context, claimUID string) error } type GoodDriver struct { drapbv1.UnimplementedNodeServer mu sync.Mutex cdiDir string devMgr DeviceManager } func (d *GoodDriver) NodeUnprepareResource(ctx context.Context, req *drapbv1.NodeUnprepareResourceRequest) (*drapbv1.NodeUnprepareResourceResponse, error) { if req == nil || req.ClaimUid == "" { return nil, status.Error(codes.InvalidArgument, "claim UID must be provided") } d.mu.Lock() defer d.mu.Unlock() claimUID := req.ClaimUid cdiFileName := fmt.Sprintf("vendor-dra-%s.json", claimUID) cdiFilePath := filepath.Join(d.cdiDir, cdiFileName) // 1. Idempotently remove dynamic CDI registry spec if err := os.Remove(cdiFilePath); err != nil && !errors.Is(err, os.ErrNotExist) { return nil, status.Errorf(codes.Internal, "failed to purge CDI manifest %s: %v", cdiFilePath, err) } // 2. Teardown underlying hardware context idempotently via persistent state tracker if err := d.devMgr.ReleaseDevice(ctx, claimUID); err != nil { return nil, status.Errorf(codes.Internal, "failed to release hardware allocation for claim %s: %v", claimUID, err) } return &drapbv1.NodeUnprepareResourceResponse{}, nil } ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Kubernetes 1.32 DRA Structured CDI Claim Lifecycle & Deterministic Unprepare Guardrail

Kubernetes 1.32 DRA Structured CDI Claim Lifecycle & Deterministic Unprepare Guardrail defines an industrial-grade behavioral standard for devops engineering. Enforces strict conformance to Kubernetes 1.32 Dynamic Resource Allocation (DRA) structured parameters and Container Device Interface (CDI) device claim lifecycles. Mandates idempotent NodeUnprepareResource execution, transactional finalizer synchronization, and atomic cleanup of dynamic /var/run/cdi specifications. Prevents device leakage and node-level orphaned hardware allocations during Pod eviction, ungraceful termination, or kubelet restarts. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Leaking physical GPU/accelerator allocations via non-idempotent DRA NodeUnprepare execution and static CDI spec abandonment Without an explicit system instruction file, developers spend hours debugging silent failures.

Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	Leaking physical GPU/accelerator allocations via non-idempotent DRA NodeUnprepare execution and static CDI spec abandonment	Critical	Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production. Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture Inconsistency	AI assistants produce mixed paradigms across files, creating fragmented codebase conventions.	Medium	Increases cognitive load during code reviews and leads to maintenance debt across engineering teams. Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.

Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

Engineers MUST ALWAYS implement NodeUnprepareResource as a strictly idempotent gRPC handler, returning status Code OK (nil error) if the target claim or CDI device has already been purged.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.