Kubernetes

Kubernetes

Standalone install? If this session was not initialized by the TAO skill bank plugin, run the tao-setup skill first (host preflight, credentials, cross-skill discovery).

Submits TAO container jobs as Kubernetes Jobs. Works on any cluster reachable via kubeconfig (EKS / GKE / AKS / on-prem) or in-cluster service account (when running inside a pod).

Single-pod by default; opt into multi-node distributed training via num_nodes > 1 (uses Indexed Job + headless Service, see Multi-node training below).

Preflight

Three checks: GPU host runtime ready, cluster reachable via kubectl, GPU Operator/​device plugin present.

# 0. GPU node host runtime.
# Run this on each self-managed GPU worker node or in the node image build.
# Set TAO_K8S_SKIP_NODE_RUNTIME_CHECK=1 only when using managed GPU nodes whose
# driver/​toolkit lifecycle is owned by the cloud provider or GPU Operator policy.
if [ "${TAO_K8S_SKIP_NODE_RUNTIME_CHECK:-0}" != "1" ]; then
  TAO_SKILL_BANK_ROOT="${TAO_SKILL_BANK_ROOT:-$PWD}"
  SETUP_SCRIPT="${TAO_SKILL_BANK_ROOT}/​skills/​platform/​tao-setup-nvidia-gpu-host/​scripts/​setup-nvidia-gpu-host.sh"

  bash "$SETUP_SCRIPT" --backend kubernetes --check-only || {
    echo "MISSING: TAO Kubernetes GPU node runtime is not ready."
    echo "For self-managed GPU nodes, run after user approval:"
    echo "  bash \"$SETUP_SCRIPT\" --backend kubernetes --install --yes"
    echo "For managed clusters, verify the node image/​GPU Operator policy installs driver 580 and toolkit 1.19.0, then set TAO_K8S_SKIP_NODE_RUNTIME_CHECK=1."
    exit 1
  }
fi

# 1. Cluster reachable (kubeconfig OR in-cluster service account)
command -v kubectl >/​dev/​null 2>&1 || {
  echo "MISSING: kubectl not found on PATH. Install kubectl to submit Jobs."
  exit 1
}
kubectl cluster-info >/​dev/​null 2>&1 || {
  echo "MISSING: no reachable cluster (kubeconfig at ~/​.kube/​config, \$KUBECONFIG, or in-pod service account)."
  echo "Configure kubectl for your cluster, or set \$KUBECONFIG:"
  echo "  EKS: aws eks update-kubeconfig --name <cluster> --region <region>"
  echo "  GKE: gcloud container clusters get-credentials <cluster> --region <region>"
  echo "  AKS: az aks get-credentials --resource-group <rg> --name <cluster>"
  echo "  local: minikube start   (see 'Local cluster' below)"
  exit 1
}

# 2. NVIDIA GPU Operator present (soft check — warn, don't fail)
gpu=$(kubectl get nodes -o jsonpath='{range .items[*]}{.status.allocatable.nvidia\.com/​gpu}{"\n"}{end}' 2>/​dev/​null | grep -v '^$' | head -1)
if [ -z "$gpu" ] || [ "$gpu" = "0" ]; then
  echo "WARN: no nvidia.com/​gpu allocatable on this cluster."
  echo "Install the NVIDIA GPU Operator before submitting GPU jobs:"
  echo "  https://docs.nvidia.com/​datacenter/​cloud-native/​gpu-operator/​latest/​getting-started.html"
fi

The GPU node runtime check is mandatory for self-managed nodes. For managed clusters where the client is not running on a GPU worker, verify the provider node image or GPU Operator policy and set TAO_K8S_SKIP_NODE_RUNTIME_CHECK=1 instead of running the installer on the client. The GPU-capacity warning here is a soft check; the submit verb re-checks allocatable nvidia.com/​gpu and hard-fails before applying the manifest (there is no gang scheduling, so a too-big Job would sit Pending forever).

Credentials & configuration

• Kubeconfig (one of):
  • ~/​.kube/​config — default discovery path
  • $KUBECONFIG — alternate path
  • In-cluster service account — used when running inside a pod (no kubeconfig needed)
• TAO_K8S_NAMESPACE (optional): default namespace for Job submission. Defaults to default.
• TAO_K8S_CONTEXT (optional): kubeconfig context name to switch clusters.
• NGC_KEY (optional): for nvcr.io image pulls. If you've pre-created an image-pull secret in the target namespace, reference its name in the rendered manifest's imagePullSecrets.
• AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY / S3_BUCKET_NAME / S3_ENDPOINT_URL (optional): for S3 dataset I/​O (storage tier C), injected into the pod via the per-job Secret (envFrom.secretRef), never inline. Legacy ACCESS_KEY/SECRET_KEY are mapped by tao-data-io.

Do not ask for Brev or SLURM credentials for Kubernetes runs. Ask for S3 credentials only when the selected workflow uses s3:// inputs or outputs, and ask for model-specific credentials such as HF_TOKEN only when the selected model requires them. Before launch, verify the selected namespace can create Jobs, dataset/​result paths are visible from the pod, and PVC/​mounted filesystem paths are proven to be mounted into the job container; an agent-host local path is not sufficient proof.

Execution — the four verbs

tao-run-on-kubernetes is a platform consumer: it runs a spec-bundle via kubectl, mutating only the job-record. No nvidia-tao-sdk, no tao_sdk import — jobs are submitted with plain kubectl apply. $BANK = ${TAO_SKILL_BANK_PATH}.

submit

1. GPU-capacity gate — hard-fail first (no gang scheduling → a too-big Job sits Pending forever):

   ALLOC=$(kubectl get nodes -o jsonpath='{range .items[*]}{.status.allocatable.nvidia\.com/​gpu}{"\n"}{end}' | awk '{s+=$1} END{print s+0}')
   [ "${ALLOC:-0}" -ge "$NUM_GPUS" ] || { echo "insufficient GPUs: need $NUM_GPUS, allocatable $ALLOC"; exit 1; }
   

2. Storage tier (via tao-data-io): A = mount a bound PVC/​NFS holding the data (author the mount paths, no fetch — the air-gap answer, and what the packaged template does); C = ephemeral: an initContainer fetches from S3 into a shared emptyDir and a final step uploads results to S3 before TTL.

   Tier C holds the GPU while it downloads. A pod reserves nvidia.com/​gpu for its whole lifetime, initContainers included, so a large tier-C fetch — or a first-time multi-GB image pull — is billed and reaper-eligible idle GPU time, exactly like pulling inside a SLURM allocation. Prefer tier A when the data is already on a PVC; choose tier C knowingly, for small inputs.

   A producer action request may declare several mounts, including duplicate- source aliases for logical and embedded absolute paths. Read references/​action-request.md and use its staging map plus packaged renderer. For mode=config, materialize the producer's nested spec first, stage that exact generated file, and pass it back to the renderer so the pod receives a verified read-only config mount. The legacy single-root template cannot represent that contract.

3. Open the record — mints the id, binds results_dir, before launch:

   JOB_ID=$("$BANK/​scripts/​tao_job_record.py" open --platform kubernetes --image "$IMAGE" \
     --network-arch "$ARCH" --action "$ACTION" --storage-tier "$TIER" --results-dir "$RESULTS_DIR")
   

   results_dir must be a mounted (surviving) volume path or an S3 prefix — ttlSecondsAfterFinished deletes the Job and its logs after it ends, so nothing is recoverable from the Job object later.

4. Render, gate, apply, and record RUNNING. For a producer action request, follow references/​action-request.md; it owns backend-name normalization, conditional Secret references, native argv rendering, server dry-run, and binding the applied object name to the job-record. For a simple one-root spec-bundle, render templates/​k8s/​single-pod-job.yaml.tmpl, run redact_secrets.py lint plus kubectl apply --dry-run=server, apply it, and mark the record with backend-ref=<namespace>/<actual-object-name>.

A submit that skipped the gate or the open has no id — so it cannot launch.

status

Keep K8S_JOB_NAME from submit. On reattach, read the job-record's backend_ref=<namespace>/<name> and recover both values from that field; do not assume the Kubernetes name equals the record id.

kubectl get job "$K8S_JOB_NAME" -n "$NAMESPACE" \
  -o jsonpath='{.status.conditions[0].type} {.status.active} {.status.succeeded} {.status.failed}'

logs

kubectl logs -n "$NAMESPACE" -l "job-name=$K8S_JOB_NAME" --tail "${N:-200}"

cancel

kubectl delete job "$K8S_JOB_NAME" -n "$NAMESPACE" --cascade=foreground
if [ -n "${CRED_SECRET:-}" ]; then
  kubectl delete secret "$CRED_SECRET" -n "$NAMESPACE" --ignore-not-found
fi
"$BANK/​scripts/​tao_job_record.py" mark "$JOB_ID" --state CANCELED --source agent

Multi-node (nodes > 1)

Same four verbs, plus:

1. Version gate: require k8s ≥ 1.28 (kubectl version -o json) — the pod hostname <job>-<index> (PodIndexLabel) that MASTER_ADDR=<job>-0.<svc> resolves to needs it; on older clusters rank-0 hangs at rendezvous.
2. Capacity gate ×nodes: hard-fail unless allocatable GPUs ≥ gpus_per_node × nodes (no gang scheduling → a partial start leaves rank-0 waiting forever).
3. Render templates/​k8s/​indexed-job.yaml.tmpl — the headless Service + Indexed Job + rendezvous env (WORLD_SIZE = node count, NODE_RANK from JOB_COMPLETION_INDEX, MASTER_ADDR=<job>-0.<svc>, /​dev/​shm 16Gi so NCCL doesn't silently hang). kubectl apply -f creates the Service and Job together; cancel deletes the Job (Foreground) and the Service.
4. NCCL probe first (as SLURM) — a 2-node all-reduce with a timeout; on hang, set the cluster NCCL env and re-probe; cache per cluster.

Local cluster (development, CI, and evals)

A throwaway minikube/​kind cluster exercises admission, the four verbs, job-record wiring, and log plumbing without cluster quota — and is what an agent-driven eval should provision for itself. kubectl and minikube are single static binaries needing no root, so a non-root CI container can install them itself.

Two prerequisites keep a rendered Job Pending, and the first masks the second: the PVC the template mounts must exist (persistentvolumeclaim "<name>" not found fires before any GPU complaint), then a Job requesting nvidia.com/​gpu on a GPU-less cluster reports Insufficient nvidia.com/​gpu and waits forever. Render NUM_GPUS=0 for a lifecycle-only run and say GPU scheduling was not verified; on a Linux GPU host, minikube start --driver=docker --gpus all passes real GPUs through, so one GPU box suffices for a GPU-real smoke.

Install commands, driver choice, the container/​host-networking caveat, and the fake-device-plugin middle option: references/​local-cluster.md.

Container shell

The simple single-pod template invokes its command via /​bin/​sh -c (POSIX sh, present in busybox/​distroless as well as TAO images). For producer action requests, an args-mode command and its arguments are native container argv; a producer that needs a shell declares the shell and its script explicitly. A simple config-mode command also becomes native argv after {config_path} is substituted. A producer-owned config command that is itself a multi-line shell script is preserved verbatim under /​bin/​sh -c; the renderer never constructs shell text from config values.

GPU Operator dependency

The submit verb refuses to launch GPU jobs on a cluster with no nvidia.com/​gpu allocatable. For self-managed clusters, first run the tao-setup-nvidia-gpu-host install action on every GPU worker node or bake the same package set into the node image:

bash skills/​platform/​tao-setup-nvidia-gpu-host/​scripts/​setup-nvidia-gpu-host.sh --backend kubernetes --install --yes

Then install the NVIDIA GPU Operator or device plugin:

helm repo add nvidia https://helm.ngc.nvidia.com/​nvidia
helm repo update
helm install --wait gpu-operator -n gpu-operator --create-namespace nvidia/​gpu-operator

Full guide: https://docs.nvidia.com/datacenter/cloud-native/gpu-operator/latest/getting-started.html

Multi-node training (distributed)

Set num_nodes > 1 (see the Multi-node (nodes > 1) verb steps above) to run distributed training across N pods. Rendering templates/​k8s/​indexed-job.yaml.tmpl provisions:

1. A headless Service named after the Job (selector: job-name=<job-name>, clusterIP: None, publishNotReadyAddresses: true so pods can rendezvous before they're all Ready).

2. An Indexed Job with parallelism = completions = num_nodes, completionMode: Indexed. Each pod gets JOB_COMPLETION_INDEX injected by k8s automatically (= the node rank).

3. A command wrapper that exports the rendezvous env vars before invoking the user command. Two naming conventions are exported simultaneously:

   Env var	Value	Read by
   WORLD_SIZE	num_nodes	TAO PyTorch container's nvidia_tao_pytorch/​core/​entrypoint.py (uses this to mean node count, even though PyTorch's own convention is total processes)
   NUM_GPU_PER_NODE	gpu_count	TAO PyTorch container's entrypoint
   NNODES	num_nodes	torchrun and PyTorch-standard rendezvous
   NPROC_PER_NODE	gpu_count	torchrun
   NODE_RANK	$JOB_COMPLETION_INDEX	both
   MASTER_ADDR	<job-name>-0.<job-name> (pod-0's DNS)	both
   MASTER_PORT	29500	both (TAO's default)

   Both naming conventions are set so TAO entrypoints (dino train, etc.) and raw torchrun commands work without modification.

For a TAO entrypoint, the container reads spec.train.num_nodes and the wired env vars — e.g. dino train -e /​tmp/​spec.yaml with gpu_count=8, num_nodes=4 (4 × 8 = 32 GPUs total).

For raw torchrun-based commands (non-TAO containers), the wrapper invokes:

torchrun --nnodes=$NNODES --nproc-per-node=$NPROC_PER_NODE --node-rank=$NODE_RANK \
  --master-addr=$MASTER_ADDR --master-port=$MASTER_PORT train.py

The capacity check sums across nodes: gpu_count × num_nodes ≤ cluster's allocatable nvidia.com/​gpu.

Cluster requirements for multi-node

• k8s 1.28+ is required for stable pod hostnames in Indexed Jobs (the PodIndexLabel feature). On older clusters the MASTER_ADDR=<job>-0.<svc> DNS lookup fails. Verify with kubectl version.
• Pod-to-pod networking must be open on port 29500 (PyTorch default; configurable via MASTER_PORT env var). Most CNIs (Calico, Cilium, AWS VPC CNI) allow this by default; restrictive NetworkPolicies must be relaxed.
• NCCL in the container talks GPU-to-GPU; if the cluster has multi-NIC nodes or RDMA, set NCCL_SOCKET_IFNAME / NCCL_IB_HCA in the container env of the rendered manifest.

Reference reading

• Kubernetes Indexed Job: https://kubernetes.io/docs/concepts/workloads/controllers/job/#completion-mode
• Indexed Job for batch ML: https://kubernetes.io/blog/2022/06/01/indexed-jobs-mpi/
• PyTorch distributed (env-var rendezvous): https://pytorch.org/docs/stable/elastic/run.html
• NCCL networking tuning (NCCL_SOCKET_IFNAME, NCCL_IB_HCA): https://docs.nvidia.com/deeplearning/nccl/user-guide/docs/env.html

Kubernetes operator alternatives

For more sophisticated topologies (gang scheduling, PyTorch elastic / fault-tolerant training, MPI / Horovod, RDMA setup), reach for an operator instead of plain Indexed Job:

• MPI Operator — https://github.com/kubeflow/mpi-operator — for MPI / Horovod workloads.
• Kubeflow Training Operator (PyTorchJob, TFJob) — https://www.kubeflow.org/docs/components/training/ — for elastic PyTorch training with built-in restart logic.
• Volcano — https://volcano.sh/ — gang scheduling, queues, fair-share. Useful in shared multi-tenant clusters.
• Kueue — https://kueue.sigs.k8s.io/ — quota / queue layer on top of any of the above.

This skill's Indexed Job path is intentionally simple and dependency-free; if you need elastic restart or gang scheduling, layer one of these on top and submit jobs through the operator's CRD instead.

Common error patterns

No nvidia.com/​gpu resources allocatable on the cluster — the GPU Operator (or NVIDIA Device Plugin) isn't installed. Install per the link above; verify with kubectl get nodes -o jsonpath='{.items[*].status.allocatable}'.

ImagePullBackOff / ErrImagePull — the cluster can't pull the image. For nvcr.io: pre-create an image-pull secret in the namespace and reference it as the pod's imagePullSecrets in the rendered manifest: Feed the key over stdin — --docker-password=$NGC_KEY would put the secret in argv, where it is visible in the host's process table and shell history:

set -a; source /​path/​to/​.env; set +a   # omit if already exported
kubectl create secret generic ngc-pull-secret -n tao-jobs \
  --type=kubernetes.io/​dockerconfigjson \
  --from-file=.dockerconfigjson=/​dev/​stdin <<EOF
{"auths": {"nvcr.io": {"username": "\$oauthtoken", "password": "${NGC_KEY}"}}}
EOF
# Verify without reading the secret back:
kubectl get secret ngc-pull-secret -n tao-jobs >/​dev/​null && echo SECRET_OK

Pod stays Pending forever — kubectl describe pod -l job-name=$JOB_ID shows the scheduling reason in the Events. Common causes: insufficient GPU capacity (Insufficient nvidia.com/​gpu), no node matches the pod's nodeSelector, missing image-pull secret, or PVC mount failure.

OOMKilled (exit 137) — container exceeded memory. Reduce batch size, lower max_length, or add a memory request/​limit and target a larger node.

CredentialError: Could not authenticate to a Kubernetes cluster — neither kubeconfig nor in-cluster auth worked. Run kubectl get nodes to verify your config, or set $KUBECONFIG to the right path.

What this skill does NOT support (yet)

• Elastic / fault-tolerant training. Indexed Job has backoff_limit=0 — failures fail the whole training run. For elastic restart (e.g., resume from checkpoint after a node death), use Kubeflow's PyTorchJob operator instead.
• Gang scheduling. Indexed Job pods are scheduled independently — no all-or-nothing. Multi-node training will partially start if only some pods can be scheduled (rank-0 will hang waiting for peers). For all-or-nothing scheduling on shared clusters, use Volcano or Kueue.
• MPI / Horovod. Use the MPI Operator. The Indexed Job path here is PyTorch-distributed-shaped (env-var rendezvous on MASTER_ADDR:MASTER_PORT).
• Auto-creating image-pull secrets from $NGC_KEY. You pre-create the secret in the target namespace and pass the name. K8s namespace conventions vary widely, so we keep secret creation explicit.