agents.default and agents.nodes.<id> in the cluster's settings hold
everything agent.yaml can say but the agent's id, control planes, address and
certificate, which stay in the file and are refused there. The control plane
sends each node its settings on register and, a second apart, when they
change; an agent whose settings changed checks they load beside its file,
keeps them and starts again on them, engines serving throughout. An edited
agent.yaml that loads restarts the agent too. History, audit, ctl config, the
console and the portal's settings page cover them as the rest of the
settings.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Conflicts: config imports and docgen sources (both kept); agent.pb.go
regenerated with buf from the merged proto (MIG devices and trace context).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
A reconcile pass that does something is a trace, with placement (where it
went, or every candidate turned down), scale-up/down, drain, stop, eviction,
preemption, reaping and restarts beneath it. A replica's start is a span open
from placement until it serves; the start command carries its context in a
new ControlMessage.trace field, and the agent continues the trace through
the weights fetch, engine launch, rendezvous and readiness wait. Stops,
drains, adoption and engine installs are traced on the node, model jobs are
a trace with a span per step linked to the replica's start, and agent.yaml
takes the same tracing block as server.yaml. Off, every span is the no-op one
and commands carry nothing.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Discovery reports a card in MIG mode as its instances instead of the whole
card, on both paths: nvidia-smi (-L names them, -q -x gives their memory,
ids and processes) and NVML (GetMigMode, GetMaxMigDeviceCount,
GetMigDeviceHandleByIndex, behind an interface so it is tested with a fake).
Each instance has its MIG UUID, its own memory, and a class from the card's
and the profile: a100-80g-mig-3g.40gb. Placement numbers instances
1000 + 100 x card + instance and every view shows them as card/migN.
A replica on MIG runs on exactly one instance: a process opens one MIG
device and instances have no NVLink between them, so tp, pp, gpus or nodes
above one on a MIG class are refused in catalog validation and again in
placement, and the planner offers one instance or none. The agent gives
the engine CUDA_VISIBLE_DEVICES=MIG-<uuid> (no Vulkan device variable on
MIG). Memory and processes are per instance; heat, power and wear the
card's; utilisation is left out rather than reported as zero. A card in MIG
mode with nothing carved stays out of placement with the reason, and
llmgw doctor reports each card's mode and instances and warns of the states
in which nothing can run. ctl nodes, ctl status, the console and the plan
count devices by class. docs/install.md has a MIG section.
Written against fakes of nvidia-smi and NVML output; not yet run on MIG
hardware.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
For machines nobody here can log into. It reads the GPUs and their
nvidia-smi topology, NVSwitch and the fabric manager, every InfiniBand
and RoCE port with its counters and RoCE v2 GID, the RDMA and
GPUDirect kernel modules, the agent's declared fabrics against the
adapters, the management interface NCCL will bootstrap over, the
agent unit's memlock limit and the engines installed - and says what
is wrong and how to fix it, most serious first, with the NCCL
environment a shard on each fabric would be given. --json writes every
fact it concluded from, to send back. It exits non-zero when something
fails.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Two bugs found while verifying mTLS against real machines.
session cancelled its own derived context and then asked that context
whether the agent was shutting down. The answer was always yes, so every
stream error read as a clean close: the log said err=<nil>, the backoff
reset, and an agent whose certificate the control plane refused hammered it
forever at the base interval with nothing to diagnose. It now keeps the
parent context to answer that question, and a refusal reaches the operator
naming both the certificate and the claim.
Cancelling the context also did not stop the agent. HTTP/2 watches the
context while the request body is being written, and a bidirectional stream
spends its life blocked on the read side instead, so the read never returned.
Measured on a deployed node: `systemctl stop llmgw-agent` took 90 seconds and
ended in SIGKILL, on every restart. Closing the response when the context
ends is what actually unblocks it.
TestAgentStopsWhenContextEnds hangs reliably without the second fix, which is
the only reason to trust that it tests it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
One bidirectional connect-go stream per node, carrying registration, heartbeats
and shard status up, and start, stop and drain down. The agent dials out: GPU
nodes sit behind firewalls far more often than a control plane does, and an
outbound connection needs no inbound rule on every node in the fleet.
- registration carries the whole hardware inventory, so there is no separate
discovery call and a reconnecting agent refreshes what the scheduler knows.
The fabric labels travel with it; they cannot be inferred from the wire, so
losing them in transit would silently disable multi-node placement.
- agentsvc is both the stream handler and the reconciler's dispatcher, because
it holds the open streams and is therefore the only thing that can deliver a
command to a node.
- the agent validates a profile before launching anything, since an engine that
refuses a profile does so after minutes of loading, then supervises the
process and reports every transition with the engine's output tail on failure.
- reconnects forever with jittered backoff. A control plane restart must not
require touching every GPU node, and a fleet must not reconnect in lockstep
and knock it over again. Engines keep serving throughout, because the router
talks to them directly.
llmgw agent is real now, and llmgw server runs a control plane whenever any
model declares a profile. The static endpoint list stays for router-only runs.
Verified with real binaries as separate processes: the agent registers, a
replica is placed, an engine launches through the vLLM adapter's actual argument
construction, streaming traffic is served, and killing the agent moves the node
through unreachable to lost with placement explaining why nothing can run.
config.Model and catalog.Model were the same thing described twice, so the
router now reads catalog entries directly and the validation rules live in one
place.
Still missing: mTLS. The stream is plaintext HTTP/2 and must stay on a trusted
network until that lands.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
NVML is the only source of NVLink topology, and that topology is what keeps a
tensor-parallel group off the slow path inside a node. It needs cgo, so it sits
behind the nvml tag and the default build keeps using nvidia-smi.
Discover() picks the backend and falls back to nvidia-smi when NVML fails,
logging the fallback rather than performing it silently: on a node that is meant
to have working NVML, a quiet downgrade hides a broken driver installation and
costs the scheduler its topology.
CI now compiles the tagged build. That immediately paid for itself: ErrNoNVML
was declared only in the untagged file, so the tests did not compile under
-tags nvml. It is now declared where both builds can see it.
Not verified: the NVML path has never run against a driver, because there is no
GPU machine available. The NVLink domains it reports should be treated as
unverified until someone runs `llmgw agent inventory` on a real node.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Everything here works without GPUs and is covered by tests. The control plane
connection is not built yet, so llmgw agent itself is still a stub and the phase
exit criterion is not met.
- discovery: IB from /sys/class/infiniband, parsing the formats sysfs actually
uses and telling native InfiniBand from RoCE; GPUs via nvidia-smi, the
cgo-free path, with health flags for uncorrected ECC and memory already held
by another process. A node without IB is not an error, it is a single-node
island.
- engines: vLLM and SGLang command and environment construction, kept free of
process handling so it stays testable. The NCCL environment is the part the
plan marks critical: NCCL_IB_HCA lists only the chosen fabric's adapters,
because leaving it open lets NCCL pick an adapter on a fabric where the peer
is unreachable, and the job then hangs instead of failing.
- validation before launch: no mixed GPU types in a tensor-parallel group, the
node/GPU/TP arithmetic has to add up, and fp8 is refused below compute
capability 8.9 rather than silently falling back to a slower path.
- supervisor: process groups, because engines fork workers that hold GPU memory
and outlive a signal sent only to the leader; a bounded log tail, since engine
output is the only diagnosis when loading fails; Starting separate from
Loading, because a 70B model legitimately takes minutes; and orphan adoption
through pid files fingerprinted with the command line, since pids get reused
and adopting an unrelated process is worse than leaking the original.
- readiness is two questions: /health says the process is up, /v1/models says
the weights loaded. Routing on /health alone sends traffic into a loading model.
- llmgw agent inventory reports what the scheduler would see on a node.
One plan correction: GPU class sizes come from the driver in GiB, which does not
always match the marketing name. An L40S is sold as 48GB and reports 44.99 GiB,
so its class is l40s-45g, not l40s-48g. Consistency matters more than matching
the box, because that number decides whether a model fits. Plan §2 and §5.1
updated.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
ilkerandClaude Opus 5