Commit Graph
19 Commits
Author SHA1 Message Date
Ilker ManapandClaude Opus 5.5 daed835d88 Measure each node's CPU and memory, and give every node a page
The nodes are CPU machines, and nothing measured how busy one was: the
heartbeat carried GPU memory and disk, and llmgw_node_memory_bytes is the
total. The agent now reads /proc between heartbeats - CPU across all
cores, load averages, memory used and available, and each engine's
process group's cores and resident memory - and sends it with the
heartbeat. Nothing new runs on the nodes and Prometheus needs no new
target: the control plane exports it with the rest of the fleet, as
llmgw_node_cpu_utilization_percent, llmgw_node_cpus, llmgw_node_load,
llmgw_node_memory_used_bytes, llmgw_node_memory_available_bytes,
llmgw_shard_cpu_cores and llmgw_shard_memory_bytes. A measurement more
than a minute old is left out rather than repeated.

The cluster page's node table shows CPU and RAM as bars, and each node
links to a page of its own: current CPU, RAM, load and disk, the engines
on it with their cores and memory, and an hour of CPU, RAM, load,
per-model cores and memory and queue depth from Prometheus. It refreshes
in place.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 23:21:23 +02:00
Ilker ManapandClaude Opus 5.5 33e678ab84 Show a node's logs on the admin page
Seeing what a node did meant ssh through a jump host, to a machine whose
address nobody remembers, to read a journal only root may open. When an
engine install failed on a new node today, the reason was one line — and it
was four steps away from the page that said the install had failed.

Each node's row on the cluster page now links to its logs: the agent's own,
and every engine running there, chosen from the list the node itself sends.
The page can follow, refreshing every five seconds, and is on both the admin
listener and /admin. `llmgw ctl logs NODE [--source SHARD] [-n N]` reads the
same.

They travel over the stream the agent already holds, so they need nothing
the control plane does not already have: a request goes down, the lines come
back, and a reply that does not come in ten seconds is an agent too old to
answer. The agent keeps its last 2000 lines in memory as well as writing them
wherever it did before; the engines' last few hundred lines were already kept
and sent only when one crashed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 12:27:47 +02:00
Ilker ManapandClaude Opus 5.5 a40fc53e09 Wait for a new machine's own apt, and retry a failed install sooner
Found by building a node from nothing. Its agent tried to install libgomp1
while cloud-init and unattended-upgrades were running apt, and failed with
"Unable to lock directory /var/lib/apt/lists/": DPkg::Lock::Timeout covers
dpkg's lock, not the one `apt-get update` takes on its lists. The node was
correctly kept out of placement and said why, and then sat idle for the ten
minutes until the next pass.

A package command that fails only on a held lock is now retried for up to
ten minutes, reported as "waiting for another apt-get to finish" rather than
as a failure. A pass that does fail is retried after a minute, backing off to
ten.

The weights directory is created when the agent starts rather than by the
first download, so a new node reports its disk from its first heartbeat.

Onboarding takes several control plane addresses, comma separated, so a new
node gets the same failover list as the rest.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 12:14:22 +02:00
Ilker ManapandClaude Opus 5.5 7d97c6b74f Install a node's engines on the node, instead of trusting what is there
A node ran whatever llama-server somebody had once unpacked on it. Onboarding
checked an engine only when told its path, installed none, and a node with
nothing on it registered as ready. The one time that went wrong it went wrong
invisibly: the binary was there, executable, and could not start for want of
libgomp1, while the node reported healthy.

The control plane now says which engines every node has, at which version —
`engines:` in server.yaml, defaulting to the llama.cpp build this release was
checked against — and each agent converges on it. What only the node can
know, the node works out: the build for its processor and driver (CUDA with
its runtime when an NVIDIA driver is loaded, CPU otherwise), the OS packages
that build needs from its own package sources, and whether the result runs.
Every archive is checked against the sha256 GitHub publishes for it and
unpacked refusing any path or link that leaves the install directory. ldd
names a missing library outright; running `--version` proves the rest. Only
then is a directory marked installed, and it is checked again every ten
minutes, because an unrelated upgrade can remove a library.

An engine is reported only once installed and seen to run, or when the
agent's configuration names it on purpose — never because something happened
to be on PATH. The agent now says when it has probed, so an empty list means
"has none" rather than "too old to say": a node rebuilt from nothing is no
longer a candidate for every model at the moment it can run none of them.
Placement's refusal carries the node's own words, "installing: downloading
llama-b10991-bin-ubuntu-x64.tar.gz (16 MB)", and so do `ctl nodes` and the
cluster page, along with a warning for a CPU without AVX2 — the VM CPU type
that makes everything five times slower and nothing look wrong.

Agents also report their OS, architecture, vector extensions and NVIDIA
driver. Onboarding installs llmgw itself from the CI release for the node's
architecture, checked against the release's checksums, rather than copying
whatever binary the operator's machine had.

vLLM and SGLang are not installed yet: they are Python environments of
several gigabytes, not an archive, and still have to be named in the agent's
configuration.

Also fixes a race on the weights fingerprint, which two heartbeat loops touch
during a failover.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 10:59:59 +02:00
Ilker ManapandClaude Opus 5.5 20deb22dfa Let a node describe itself instead of being described by hand
CI / test (push) Successful in 1m47s
Every agent file on the cluster named its own node, its own address, the
path to llama-server and two weight directories — different on every node,
kept true by hand, and not true: node05 carried "ram: 32g" beside a measured
31 GB, looked for weights in an empty directory while fetching them into
another, and the other four never looked in theirs at all, so four nodes
reported no disk. Growing a node's RAM would have gone unnoticed, because
memory was read once, at registration.

The agent now finds these out. Its id is the hostname, which is also the
certificate's common name. Its address is the one on the route to the
control plane, which the kernel picks for a UDP dial without sending
anything. llama-server is looked for on PATH and then where release archives
are unpacked. A missing nvidia-smi is a node without NVIDIA cards rather
than a failed discovery — which also cut discovery short before InfiniBand
on every CPU node not told to skip GPUs. Fetched weights land in
/var/lib/llmgw-weights by default, and wherever they land is always looked
in.

Memory is read on every heartbeat, and installed engines are probed again
each minute and sent when they change, so a VM given more RAM or a node
given vLLM becomes a candidate without anyone restarting its agent. The
control plane logs both changes, since "the node now qualifies" is the
answer to why a model placed an hour after it was asked for.

What is written still wins. The agent file shrinks to the control plane's
addresses and the TLS files, the same on every node; onboarding writes only
the overrides it was given. What cannot be found stays configuration: which
fabric an adapter is on, because OpenSM's default prefix is the same on all
of them.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 10:13:42 +02:00
Ilker ManapandClaude Opus 5 03e38e7dda Carry the profile fingerprint to the agent and back
CI / test (push) Successful in 1m39s
The stale-profile flag could not fire where it matters. The control plane
keeps no record of a running replica across its own restart — it rebuilds
them from what the agents report — and adoption left the fingerprint empty,
so every replica read as unknown afterwards. That is precisely the moment
the catalog is most likely to have been edited: change the configuration,
restart the server, and nothing would ever say the fleet disagrees with it.

The fingerprint now travels with StartShard, the agent keeps it beside the
pool and fabric it already echoes back, and adoption takes the replica's
version from the agent rather than from the catalog it is about to be
compared against. An agent too old to report it sends nothing, which still
reads as unknown rather than as matching.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-27 23:22:44 +02:00
Ilker ManapandClaude Opus 5 2acd794022 Stop placing engines on nodes that do not have them
CI / test (push) Successful in 1m42s
A node's registry holds an adapter for every engine whether or not its binary
exists, the agent never said which were installed, and placement carried an
Engine field it had never once read. So a vLLM replica was as happily placed on
a node with no vLLM: the node registered healthy, the shard failed minutes
later with "executable file not found" in the engine's own words, and the
reconciler tried again.

That is how fifteen gigabytes of safetensors reached this cluster's mirror
before anybody noticed it had no card and no vLLM to run them with.

Agents now probe what is installed and report it — the protocol has carried
engine_versions since it was written and nothing ever filled it in. Placement
filters on the key set, `ctl nodes` has a column, and the mirror page's serve
warning is a fact instead of a guess about cards, which would have waved
through a fleet of eight-GPU nodes that never had vLLM.

Probing resolves binaries and runs none of them. The first version asked each
engine for --version, which is fine for an engine and not fine for the wrapper
scripts people put in front of one: a script that shifts past flags it does not
recognise and then execs the server will start an inference server, at agent
startup, on every node. The agent's own test suite installs exactly such a
script and caught it. So presence is a path lookup, and the version is left to
`ctl engine-check`, which is run by somebody who meant to run the engine.

SGLang is the exception and has to execute, because a module has no path to
look up — but the command is llmgw's own one-line import rather than the
engine's launcher. Its exit code is the answer: python3 is on almost every
machine, and treating a failed import as "installed" reported SGLang on every
node in a fleet that had none, which is the failure being fixed, inverted.

Probed once, not per reconnect, and bounded by the context that registration
waits on: an agent that cannot reach the control plane is worse than one
reporting an incomplete list.

A node that reports no engines at all is not excluded anywhere — by placement,
or by the page. That is what every agent older than this reports, and emptying
a fleet on a control plane upgrade is a worse failure than the one being fixed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-27 16:11:55 +02:00
Ilker ManapandClaude Opus 5 a35e8796d2 Carry a download's progress to where somebody is looking at it
CI / test (push) Successful in 1m28s
The agent has always logged a percentage as it fetches weights, with a comment
saying a replica pulling a hundred gigabytes and one that is wedged look
identical from the control plane. They still did: the log is on the node, and
the node is not where anyone is looking when a replica has been starting for
ten minutes.

Progress now rides on the shard status and appears under the replica in `ctl
replicas` — a line rather than a column, because most replicas are not
downloading anything and a column would be empty for all of them.

It is deliberately not a state transition. Treating each chunk as one would
re-mark the shard as starting on every report and reset the timer that decides
when a slow start has become a failed one, so an hour-long download would keep
a doomed replica alive indefinitely. It arrives on its own method for that
reason, and a real transition clears it — otherwise a finished download sits in
the listing at ninety-nine percent under a shard that has been serving for an
hour.

Watchers are keyed by source rather than by shard, because a fetch is
single-flight: eight shards starting together produce one download and all
eight are waiting on it.

No percentage is invented when the server sent no length. One that stops moving
is worse than a byte count that keeps rising, so the field is absent and the
listing says "so far".

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-27 07:49:08 +02:00
Ilker ManapandClaude Opus 5 4ba84fa90e Let an agent find the leader instead of being told one address
CI / test (push) Successful in 1m32s
The second half of leadership. A standby that refuses to place but still holds
an agent's stream is worse than useless: commands travel down the stream the
agent opened, so the leader's placements fail with "no agent connected" for a
node that is plainly connected.

So a standby refuses the stream, before reading the opening message, and says
why. And an agent takes a list rather than an address, trying each in turn — a
standby refusing, a stopped control plane refusing the connection and a crashed
one never answering are the same thing from a node, and the answer to all three
is somewhere else.

`server` and `servers` are both accepted, with `server` first when both are
given: every agent configuration written before there could be a second control
plane names one address, and an operator adding a standby expects the one
already working to stay preferred. With a single address the behaviour is
exactly what it was, including the backoff — which is skipped only while there
is another address that has not just been tried, because the delay exists to
stop hammering one control plane and the next one has not been hammered.

Removed a check that asked whether one field was empty, which is how the first
run of these tests failed: the list was populated and `server` was not, and an
agent configured entirely correctly was refused by its own validation.

The tests run a real agent against a real service over h2c. The first attempt
used a plain HTTP server, and the refusal arrived as an HTTP/2 framing error
that said nothing about why — which is exactly what an operator would have seen.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-25 19:30:06 +02:00
Ilker ManapandClaude Opus 5 45e913bd10 Refresh disk and weights while the agent runs, not once when it starts
CI / test (push) Successful in 1m46s
Found by answering "where can we see this live". `ctl weights` was offering a
file for deletion that I had deleted two days earlier, and the node's disk
figure was the one it had when its agent started. Discover() is called at
registration and nowhere else, so both were frozen.

Disk is a fact about a moment, not about a machine. Sampled once, the figure
is wrong on exactly the node worth watching — the one busy filling up — and it
stays wrong until that agent restarts. The heartbeat already refreshes GPU
memory for the same reason, with a comment about noticing a foreign process
"after registration"; disk belonged beside it and I did not put it there.

The stale list cut both ways. A model fetched after registration was invisible
until a restart, so placement could not prefer the node that had just spent ten
minutes downloading it, and the disk check could not see the space it used.

Storage goes in every heartbeat, being a few numbers per filesystem. The file
list goes only when a fingerprint of paths and sizes changes, with a flag
saying the list is meant — without that, an empty list would be ambiguous
between "this node now holds nothing" and "nothing to report", and the second
reading would empty a node's inventory five seconds after it registered.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-20 09:57:25 +02:00
Ilker ManapandClaude Opus 5 774e134ed1 Refuse a node with no room, and take back only what llmgw put there
CI / test (push) Successful in 1m39s
Two halves of the same problem: nothing stopped a model being placed on a node
that could not hold it, and nothing ever removed the weights of a model that
had been deleted from the catalog.

Placement now has a disk check, shaped exactly like the memory one it sits
beside, with one addition: it is skipped on a node that already holds the
weights. A node holding the file needs no room for it, and without that the
node best placed to run a model — because it already has it — is the one most
likely to be rejected, since holding the file is what used the space.

Reclaiming is the dangerous half, so the whole design is about what it will
not do. llmgw deletes only files it fetched itself, and that is a calculation
rather than a heuristic: the cache name is a hash of the source, so the set of
wanted files can be computed from the catalog exactly. Anything without that
name was put there by an operator — scp, a shared mount, a copy by hand — and
is none of this system's business however unreferenced it looks. A model that
took a week to copy must not be removable by a command someone ran to tidy up.

The node checks every path again before unlinking it, and that duplication is
the point. The control plane knows the catalog; the node knows its disk. A
control plane that is wrong, newer than the agent, or tampered with must not be
able to talk a node into deleting something, so the agent refuses anything
outside its own cache directory or without the cache name — including a path
that tries to traverse out of it.

Listing is the default and deleting takes --collect. The summary says "asked to
remove", because each node decides, and one that refuses a path it cannot prove
it fetched is this working rather than failing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-18 09:51:05 +02:00
Ilker ManapandClaude Opus 5 b619546516 Stop trusting hardware facts that were never checked
CI / test (push) Successful in 1m32s
Three places where the system took the infrastructure's word for something
and would have failed silently on real hardware.

A declared fabric adapter that is not on the node. Fabric membership has to
be configuration — OpenSM's default subnet prefix is identical on every
fabric, so a matching prefix proves nothing — but taking it entirely on
trust was a different mistake. A typo, or a card that enumerated
differently after a reboot, produced NCCL_IB_HCA naming an adapter that
does not exist.

An adapter with no ACTIVE port. Physically linked with no subnet manager
sits in INIT: it looks healthy to anything counting adapters, carries no
data, survives a reboot, and looks like a software problem. Discovery had
recorded port state all along and placement only ever asked whether a
fabric had any adapters listed.

Both end the same way — the replica starts, passes its health checks, and
hangs on its first all-reduce, which is the failure the fabric invariant
exists to prevent arriving through a door nobody was watching. The agent
now compares declared against discovered, where both are visible for the
only time, and does not advertise a fabric that cannot carry traffic. The
reason is logged on the machine that knows it, because the operator who
typed the adapter name is the only person who can fix it. The fabric's rate
is the slowest active link, since a collective runs at the speed of its
slowest.

And NVLink topology, which no published binary could see. NVML is its only
source, the bindings need cgo, and CGO_ENABLED=0 is deliberate so the
portable binary runs on an older libc. The cost was silent: tensor groups
fall back to the lowest free indices, which is right on an SXM board with
NVSwitch and wrong on a PCIe box where bridges pair specific cards — a
group straddling two of them runs several times slower and nothing says so.
Releases now also publish an nvml build for those nodes, and
llmgw_gpu_nvlink_peers makes the difference visible: a flat zero across a
fleet means the topology is unknown rather than absent.

A test that declared mlx5_0 and mlx5_1 on a node whose sysfs held neither
had been passing, because nothing compared the two.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-17 17:29:15 +02:00
Ilker ManapandClaude Opus 5 943c23a412 Fetch a model's weights when the simple arrangement needs it
CI / test (push) Successful in 1m26s
The default arrangement is the simple one: every node keeps its own copy.
So a source naming a remote file is now fetched before the engine is
launched, rather than left to fail as a missing path minutes into a load.

Eight shards of a tensor-parallel replica start at the same instant and
want the same file; they produce one download. An interrupted fetch resumes
instead of starting over, which matters at forty gigabytes, and the
download is written beside its target and renamed only when complete — a
partial file under the model's name would be found by the next scan,
reported as present, and handed to an engine that fails on it.

The exotic arrangements need no code, which is the point. Weights on a
Lustre mount or an image exported over the fabric are simply present, and
present means nothing is fetched. The escape hatch from a distribution
mechanism is a distribution mechanism that checks first.

Wiring it up caught a regression in my own design. A bare model id —
"Qwen/Qwen2.5-7B-Instruct" — is a documented source that vLLM and SGLang
resolve themselves, and treating every non-remote source as a local path
made every existing vLLM profile fail. Only an absolute or explicitly
relative path is now checked as a file; anything else is passed through
untouched. Three agent tests failed on the same change for a better reason:
they used "/models/x", and the new check is exactly the one that catches
that.

Whole repositories of shards are deliberately not fetched here. vLLM and
SGLang do that well already, and a second snapshot downloader would be work
spent arriving back where we started.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-17 08:46:03 +02:00
Ilker ManapandClaude Opus 5 c13c567cc5 Know where the weights are, without owning the storage
CI / test (push) Successful in 1m32s
Storage will be different at every installation — Lustre, NFS over RDMA, an
image exported with SRP or NVMe-oF, local NVMe, an rsync — so llmgw observes
it rather than managing it. An agent told which directories to look in
reports what it can see; how the files got there is nobody's business here,
and a node told nothing reports nothing and behaves exactly as every node
did before this existed.

That fact buys two things. Placement prefers a node that already holds the
model over one that must first move tens of gigabytes, as a preference and
never a filter: fetching them is a valid answer, and refusing to place would
turn a slow start into no start at all. And ctl status shows what each
fabric holds.

Per fabric because fabrics are not connected to one another. Weights in
ib-a are not weights in ib-b — the only path between them is the management
network — so a model seeded into one fabric leaves the rest of the cluster
unable to serve it without a slow copy, and nothing said so before now. One
shared filer counts the same as twenty local copies, because "can this
fabric serve it" is the question being asked.

Three distinctions the tests hold to, because each is a way to get this
quietly wrong. A node that was never asked to look must rank with one that
looked and has nothing, or enabling the feature on a single node would
drain every other. An empty directory is not weights, because a
half-finished download looks exactly like one and would send placement to a
node whose engine then fails to load. And local storage is never mistaken
for shared: a filer read as local costs an unnecessary copy, while local
read as shared would have the cluster believe a model is everywhere when it
is on one node.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-17 08:21:16 +02:00
Ilker ManapandClaude Opus 5 1431426db0 Finish adopting an engine instead of stopping at "it is alive"
CI / test (push) Successful in 1m26s
Adoption set a shard to Starting and started a liveness poll, and that was
all. Nothing health-checked it, so nothing ever moved it to Ready. The
control plane then waited out the profile's startup timeout and killed a
perfectly healthy engine so it could start an identical one.

An agent restart exists precisely so that engines are not interrupted. It
was costing every model on the node a full reload, minutes of it, which is
the failure adoption was written to prevent.

Measured on node05 while deploying today's other changes: the engine
answered /health the whole time and the replica sat in Starting for three
minutes until the timeout reaped it. I had seen this earlier in the session
and worked around it by killing the engine to force a clean restart, which
made the symptom go away and left the cause in place.

An adopted shard now takes the same two paths a freshly started one does: a
rank that serves HTTP is health-checked, a worker is judged by staying
alive. Run in the background, because recovery happens before the agent
connects and a slow check must not delay registration. An engine that will
not answer is left for the control plane to replace rather than killed
locally, which would race the decision it already has a timeout for.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-16 23:58:53 +02:00
Ilker ManapandClaude Opus 5 ec1b6b04df Fix an agent that could neither explain itself nor stop
CI / test (push) Successful in 54s
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>
2026-09-16 08:03:21 +02:00
ilkerandClaude Opus 5 1d1a6aebb0 Phase 4: make a multi-node replica able to start
CI / test (push) Failing after 53s
Placement and environment generation had landed early, which made multi-node
look further along than it was. A replica spanning nodes could not come up at
all, and all three reasons came down to assumptions that only hold on one node.

Not every rank serves HTTP. The agent health-checked every shard at its own
port, but only the leader answers; workers timed out, reported Failed and took
the replica with them. Engine.ServesHTTP now says which ranks serve, and a
worker is judged by staying alive. That is deliberately weaker evidence: the
replica's real readiness is the leader answering, which only happens once every
worker has joined.

A shard is not always one process. Engine.Commands returns a sequence — every
command but the last is a sidecar kept alive for the shard's lifetime and torn
down with it, and the last one's exit is the shard's. vLLM under Ray is why: the
leader runs a Ray head and then the server against it, while a worker runs only
the join and no vLLM process at all. RayCommand had been written and tested but
never called, so launch_mode: ray would have run vllm serve against a cluster
that did not exist. Sidecars are killed with the shard, because a Ray head left
behind holds the port the next replica needs.

Start order was backwards. Workers went first, on the theory that the head
should wait for them. Both engines put the rendezvous point on rank 0, so a
worker started first has nothing to connect to. vLLM's server blocks until the
Ray cluster has the GPUs it needs, so the leader can start immediately and waits
on its own. A command can now also require that rendezvous point to be listening
before the next starts, bounded by a timeout so a head that never appears fails
the shard instead of hanging it.

Stop was also killing only the engine, leaving sidecars behind.

None of this is verified against real engines — it is tested with stub
processes. The Ray sequencing, and which launch mode a given vLLM version wants,
can only be confirmed on hardware.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-16 06:20:03 +02:00
ilkerandClaude Opus 5 75a8e76706 Survive a control plane restart without orphaning live engines
CI / test (push) Successful in 1m44s
Not persisting replica state left one hole: restarting the control plane made it
forget every replica while the engines kept running. They held GPUs the
inventory believed were free, so the next placement failed to allocate, with an
error naming the new process rather than the old one.

The fix belongs on the agent, not in a database. A row can say "running" about a
process that died; the fleet cannot.

- the supervisor writes the full shard spec, not just a pid and command line. A
  pid identifies a process; the spec is what lets it be described back to the
  control plane and matched to a replica.
- Adopt takes over an engine a previous agent left running. It is not this
  process's child, so it cannot be waited on: it is watched by polling and
  stopped by signalling its group directly. Its earlier output is gone and the
  log says so rather than presenting emptiness as silence.
- every Register reports what the agent is running, not only the first, because
  a reconnect may be a control plane restart and has to recover the same way.
- the reconciler rebuilds replicas from those reports and reclaims their GPUs.
  Anything whose model or profile left the catalog is stopped; nothing will
  route to it and it is holding cards.
- an engine the agent cannot identify is killed. A process holding GPUs that
  nothing can describe is worse than no process, because placement hands those
  GPUs out again.

Stop was also wrong for adopted shards: it checked for an exec.Cmd, which they
do not have, and reported them stopped without killing anything.

TestAgentReconnects had been passing for no reason. httptest's
CloseClientConnections does nothing to an h2c stream — prior-knowledge h2c
hijacks the connection and httptest stops tracking hijacked ones — so the agent
never reconnected, and the assertion on the connection map passed on a stale
entry. Tests now sever connections through their own listener and count opened
streams.

Plan §11 also records what multi-node still needs, since placement landing early
makes it look further along than it is: workers never become Ready because the
agent health-checks every shard while only rank 0 serves HTTP; RayCommand is
written and tested but never called; and startup is fire-and-forget.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-16 06:15:04 +02:00
ilkerandClaude Opus 5 2373726efd Agent stream: connect the fleet to the control plane
CI / test (push) Failing after 1m29s
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>
2026-09-16 02:48:21 +02:00