Brev — TAO execution glue

Brev — TAO execution glue

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).

NVIDIA Brev provides on-demand GPU instances (pre-loaded with NVIDIA drivers, CUDA, Docker, and the NVIDIA Container Toolkit). Brev is instance-based: you provision an instance, run commands on it over brev exec, and delete it when done.

This skill is deliberately thin. Provisioning and managing instances — create, search by GPU/​price, start/​stop, delete, login — is owned by NVIDIA Brev's own agent skill, not duplicated here. This skill covers only the TAO-specific part: running a TAO container on a reached instance through the four-verb docker contract, deferring the container-how to tao-run-on-docker over brev exec.

Provisioning: use the official Brev skill or MCP

NVIDIA Brev publishes an agent skill that manages instances in natural language ("create an A100 instance", "search for GPUs under $3/​hr", "stop all my instances"). Install it once — it self-registers into your agent's skills dir and is discovered at runtime:

curl -fsSL https://raw.githubusercontent.com/​brevdev/​brev-cli/​main/​scripts/​install-agent-skill.sh | bash
# installs to ~/​.claude/​skills/​brev-cli/ , ~/​.codex/​skills/​brev-cli/ , ~/​.agents/​skills/​brev-cli/

Or connect the Brev MCP server (https://docs.nvidia.com/​brev/​_mcp/​server). Either one owns login/​auth quirks, placement IDs, GPU search, and teardown flags. It does not cover container execution on the instance — that is this skill.

Preflight for this skill: the brev CLI is on PATH and logged in (headless: brev login --token "$BREV_API_TOKEN" before any other call), and you can reach a target instance — poll with a two-word command until it succeeds before issuing real work (a fresh instance reports RUNNING before sshd is up):

for i in $(seq 1 60); do brev exec <instance> "echo ok" 2>/​dev/​null | grep -qx ok && break; sleep 5; done
brev exec <instance> "echo ok" 2>/​dev/​null | grep -qx ok || { echo "instance not exec-ready"; exit 1; }

The probe must be two words, quoted as one argument. A single-token probe (brev exec <instance> -- true) passes even when every real command is broken, because brev exec [instance...] <command> treats only the LAST positional as the command — so a lone true lands in the right slot by accident while docker run ... does not. See brev exec argument form below.

Allow ≥ 600 s for the first brev exec on a new instance (SSH bring-up + first container pull); a 60–120 s wrapper timeout truncates startup and looks like a spurious exec failed.

Storage

No shared NFS/​Lustre — storage tier B/​C via tao-data-io: stage inputs from S3 to the instance's local disk (or fetch in-container) and upload results to S3 before deleting the instance. Instance-local ~/ persists across stop/​start but not across delete/​create, so the results upload must precede teardown.

Execution — the four verbs (a compound over Docker)

Brev is a compound consumer: submit reaches an instance, then defers the container-how to the four docker verbs (tao-run-on-docker) run over brev exec. It is not a symmetric peer — teardown must additionally delete the instance to stop billing. $BANK = ${TAO_SKILL_BANK_PATH}.

• submit — reach an instance (provision/​reuse via the official Brev skill or MCP; reuse an existing instance by its instance_id; wait for readiness, above). Lint the assembled command, open the record to mint $JOB_ID before launch, then run the docker submit verb inside the instance and mark RUNNING:

  redact_secrets.py lint <<<"$REMOTE_CMD"     # no inline secrets; creds as -e VAR
  JOB_ID=$("$BANK/​scripts/​tao_job_record.py" open \
    --platform brev --image "$IMG" \
    --network-arch "$ARCH" --action "$ACTION" \
    --storage-tier "$TIER" --results-root "$RESULTS_ROOT")
  brev exec <instance> "docker inspect '$JOB_ID' >/​dev/​null 2>&1 && { echo '$JOB_ID already submitted'; exit 0; }; docker run -d --name '$JOB_ID' --label 'tao-job=$JOB_ID' ..."
  "$BANK/​scripts/​tao_job_record.py" mark "$JOB_ID" --state RUNNING \
    --backend-ref "<instance>/​$JOB_ID"       # instance is part of the ref: the
                                             # container is unreachable without it
  

• status / logs — brev exec <instance> "docker inspect $JOB_ID" / brev exec <instance> "docker logs $JOB_ID", mapped to the vocab exactly as the docker verbs do. Recover <instance> from the record's backend-ref.

• cancel / teardown — remove the container, then for an ephemeral instance delete it (stops billing), then mark the record. Never leave an ephemeral instance running:

  brev exec <instance> "docker rm -f $JOB_ID"
  brev delete <instance>                      # ephemeral instances only
  "$BANK/​scripts/​tao_job_record.py" mark "$JOB_ID" --state CANCELED --source agent
  

brev exec argument form

The remote command is one argument. The CLI signature is brev exec [instance...] <command>: every positional except the last is an instance name, and -- only ends flag parsing — it does not group the words after it. So brev exec <inst> -- docker inspect "$JOB_ID" is read as instances <inst> docker inspect plus command "$JOB_ID", and fails with could not look up instance "docker" / ssh: illegal option -- - (exit 255) — an error that reads like an instance or SSH fault but is a syntax fault. Quote every remote command as a single string, exactly as brev exec --help shows.

NGC auth once per instance — never put NGC_KEY on argv (it lands in the remote process table); pipe it to --password-stdin:

IMG=nvcr.io/​nvidia/​tao/​tao-toolkit:7.2.0-pyt  # versions-key: images.tao_toolkit.pyt

# NGC auth (one-time per instance) — value never on argv.
# Single-quoted locally so $NGC_KEY expands in the instance's shell; export it
# there first (or pipe it in from the local shell, if the instance has no copy).
brev exec <instance> 'printf %s "$NGC_KEY" | docker login nvcr.io -u "$oauthtoken" --password-stdin'

# Verify auth without reading ~/​.docker/​config.json. Failure before a successful
# login = not authenticated; failure after = the key's org lacks entitlement.
brev exec <instance> "docker manifest inspect $IMG >/​dev/​null && echo AUTH_OK || echo AUTH_FAIL"

# Pull BEFORE the GPU run. `docker run` would pull implicitly, but the instance
# bills from boot, so a multi-GB first-time TAO pull is billed GPU-idle time.
# Pulling as its own step also separates a pull failure (auth/​entitlement) from
# a training failure in the logs.
brev exec <instance> "docker image inspect $IMG >/​dev/​null 2>&1 || docker pull $IMG"

# Run a TAO job (the docker `submit` verb, over brev exec)
brev exec <instance> "docker inspect '$JOB_ID' >/​dev/​null 2>&1 && { echo '$JOB_ID already submitted'; exit 0; }; docker run -d --name '$JOB_ID' --label 'tao-job=$JOB_ID' --gpus all -v ~/​data:/​data -e NGC_KEY '$IMG' visual_changenet train -e /​data/​spec.yaml"

Multi-GPU and multi-node

Multi-node is not supported on Brev — instance-based, no cross-instance coordination. Multi-GPU on a single instance is supported (up to 8× H100 / A100 / L40S); torchrun --nproc-per-node=N or PyTorch DDP work within the instance.