a075ff4120829d4febce91e7aa3782ef51ecb378
15
Commits
| Author | SHA1 | Message | Date | |
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 Ilker ManapandClaude Opus 5
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058ee382fa |
An agent reporting nothing is reporting something
CI / test (push) Successful in 1m18s
The previous commit taught the reconciler to let go of shards an agent says it is not running. It made no difference on the cluster, because the service returned early when the agent's list was empty — which is precisely the case that carries the news. So the fix was dead code in production while its unit tests passed, and they passed because they called the reconciler directly. The test added here goes through the real stream instead, and asserts only that an agent running nothing reaches the reconciler at all. That is the lesson worth keeping: a test that calls the function under test directly cannot tell you the caller never calls it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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Ilker ManapandClaude Opus 5
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aef1c143c5 |
Let go of shards an agent says it is not running
CI / test (push) Successful in 1m19s
Adoption handled "the agent has something we do not know about". The mirror image was missing: "we think the agent has something it does not". Both follow from the same rule — the fleet is authoritative about what is running (plan §6.5) — and without the second half an engine that dies while its agent survives leaves the control plane believing a replica is Ready forever. Measured on the cluster: the engine was killed, the agent restarted and registered with nothing running, and the replica stayed Ready pointing at a dead port for two and a half minutes until I stopped watching. Traffic survived, because the breaker took the endpoint out and retries covered it — 24 requests, none failed — so the only symptom was a cluster quietly running a third short. A registration follows a fresh connection, so anything dispatched over a previous one is not running by definition; there is no window where a shard is legitimately started but unreported. The previous commit's disown rule was too broad, which this turned up: when a known replica had a live shard it disowned everything the agent reported for it, including the shards we already knew. A reconnecting agent would have been told to stop the replica that was serving. It now disowns only what it does not recognise. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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Ilker ManapandClaude Opus 5
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5c837c531b |
Pin down where CPU replicas land, and where they deliberately do not
CI / test (push) Successful in 1m15s
Two tests for behaviour that looked wrong on the cluster and was not. Three replicas all landed on one node, which is correct when it is the only node registered: spreading is a preference and a model left unplaced to preserve a preference would be worse. Over successive ticks with somewhere to go, they spread. What neither test asserts, because it is not true: nothing rebalances them afterwards. A replica that moved on its own would interrupt the traffic it is serving, and v1 has no autoscaler to decide it is worth it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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Ilker ManapandClaude Opus 5
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8a062fec35 |
Stop reusing replica ids, and stop handing out ports strays still hold
The previous commit's adoption fix made a deeper problem visible instead of
fixing it. Replica ids were the model name and a counter, and the counter
restarted with the process — so a control plane that came back placed a
replica called llama-1 while an engine started before the restart, still
running on a different node, also called itself llama-1.
Two nodes then claimed the same shard id. Adoption handed it back and forth
between them, every placement landed on a port an orphan was still bound to,
and the engine failed to bind, which failed the replica, which placed another
one on the same port. On the real cluster that loop ran for minutes:
couldn't bind HTTP server socket, hostname: 0.0.0.0, port: 20002
Ids now carry four random bytes, which costs nothing and makes the collision
impossible. The "already known" branch in adoption goes back to meaning what
it says: an agent reconnecting, not a name clash across restarts.
Ports a stray still holds are also reserved now. Stopping is not instant and
an engine keeps its socket until it exits, so the allocator has to know about
sockets no replica claims — otherwise the same loop reappears in the window
between telling an agent to stop something and it actually stopping.
Two of the tests written for the previous commit had quietly become vacuous
under the new ids, asserting things about a literal llama-1 that no longer
exists. They capture the id now.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Ilker ManapandClaude Opus 5
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05bdc7d6d4 |
Add ctl bench, and fix two holes it walked into
`ctl bench` measures what a replica can actually serve, so weight, target_waiting and kv_ceiling stop being numbers somebody typed. Concurrency climbs until the SLO breaks and the last level that met it is the capacity: peak throughput arrives long after latency has become unusable, so throughput alone overstates what the hardware can serve. Queue depth and KV usage are read from the engine while it is still meeting the target, which is exactly what admission should treat as healthy. Prompts are unique per request by default. With one repeated prompt the engine's cache answers most of the prefill and the measurement describes the cache rather than the hardware; --shared-prefix asks that question deliberately, and it now produces byte-identical prompts, which the first version did not — it dropped the random header and still picked words at random, so the cache missed and the flag quietly measured the thing it exists to avoid. Running it against the cluster turned up two real defects: A replica stuck in Starting never timed out. Every other way out of that state needs the agent to report something, and when it never does the replica sits there holding GPUs and counting towards the model's replica count while serving nothing. Two of them had been like that for eight minutes past a two-minute startup timeout, and nothing would ever have moved them. They were stuck because adoption lost to a replica we had only placed. Replica ids come from the model name and a counter, so a control plane that restarts and places before its agents reconnect builds a different replica under the same id on a freshly allocated port; the agent's report of the engine that was actually serving was then discarded as already-known. The cluster pointed at port 20004 while the engine answered on 20000. The fleet is authoritative about what is running, so what we merely placed now loses to what an agent reports — unless our copy has a shard that has actually come up, in which case two things really are running and the stray is the one we did not ask for. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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Ilker ManapandClaude Opus 5
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1839832b8b |
Add a landing page and a read-only cluster dashboard
CI / test (push) Successful in 1m2s
Pasting the gateway's address into a browser returned 404, which looks like a broken endpoint rather than one that tells you how to use it. Two pages, and the split between them is a security boundary rather than a layout choice. The landing page is served without a key — it has to be, because the person reading it is the one who does not have one yet — so it contains no data at all: it says how to connect, not what is here. Model names stay behind /v1/models. It reconstructs the address from the forwarded headers so the copy-pasteable example names the address the client actually used rather than the internal one; those headers are reflected into displayed text and never used for a decision. The dashboard shows nodes, models, replicas, placement failures and usage, and lives on the admin listener only. That listener is loopback-bound and also serves pprof, which can dump the process heap — where API keys sit in plaintext — so reaching the page from elsewhere is an SSH tunnel's job. It is read-only: anything that mints a credential stays in `llmgw keys`, where it needs a shell rather than a browser session this project has no way to authenticate. Mounting the landing page uncovered a hole in the exemption list. An entry ending in "/" was a prefix rule, and "/" ends in "/", so exempting the landing page would have exempted every path there is — authentication still installed, still logging, and letting the whole API through. "/" is now exact, with a test enumerating what must and must not be exempt. Server-rendered templates and one stylesheet, embedded. The single-binary goal rules out a JavaScript toolchain and nothing on either page needs one. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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Ilker ManapandClaude Opus 5
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501db3d3e8 |
Add the llama.cpp engine, and let a profile ask for no GPU
llama.cpp is what makes a cluster with no cards useful: it serves the same OpenAI API on CPU, so the whole path — placement, supervision, scraping, scheduling, admission — can be exercised end to end on ordinary machines. Three things had to give way for it. A profile may now omit its GPU class, and that is how it says it runs on the CPU. Only engines that can actually serve without a card may omit it; for vLLM an omitted class stays an error, because otherwise a typo becomes a replica placed on a machine with no hardware and diagnosed minutes later during model loading. Placement spreads CPU replicas instead of bin packing them, since unlike GPUs there is no allocation to stop two of them sharing a machine's cores. Metric mappings are now per engine rather than per cluster. llama.cpp calls the same three numbers requests_processing, requests_deferred and kv_cache_usage_ratio, and a single global mapping would leave half a mixed fleet unmeasurable. An empty mapping still defaults to vLLM's names; one that names its own Running metric is taken as a complete statement, so the fields it leaves blank stay blank rather than being filled with names that engine cannot have. The adapter refuses multi-node and tensor-parallel profiles. llama.cpp splits across local GPUs by a different mechanism than this adapter drives, and accepting either would produce a replica that starts and then serves from one machine while the catalog believes it has several. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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Ilker ManapandClaude Opus 5
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1e3cafdc86 |
Add a private CA and mutual TLS for the agent stream
A node's identity was whatever the agent said it was. With mutual TLS the control plane compares the client certificate's common name against the claimed node id and refuses the connection when they disagree, so identity becomes something a node proves rather than something it picks. A public authority cannot supply these certificates: Let's Encrypt and its peers stopped issuing the clientAuth usage, and Go verifies client chains against it. Hence internal/tlsconf/ca.go, a small authority whose key lives on one machine and whose root is trusted everywhere, and `llmgw ctl cert` over it so issuing is reproducible instead of remembered openssl. The server certificate's hosts matter more than they look: hostname verification reads subject alternative names and ignores the common name entirely, so a certificate without the address agents dial — bare IP included — is rejected no matter what its subject says. There is a test for exactly that, because it is the failure everyone hits once. requireIdentity stays wired to false until the configuration lands, so this commit changes no running behaviour. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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 ilkerandClaude Opus 5
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e1eb1d4149 |
Phase 3: ctl, and make draining a rolling move
CI / test (push) Failing after 50s
ctl talks to a management API on the admin listener, not the client-facing one. The two have different audiences: one serves inference to whoever holds an API key, the other lets a caller cordon nodes and read the cluster's shape. - nodes surfaces unhealthy GPUs and why they are excluded. That is usually the answer when a node looks idle but nothing will schedule onto it, and it was invisible before. - explain-placement prints every candidate considered and why it was rejected. - replicas shows the shards a replica is made of, with per-shard errors. - cordon, uncordon and drain are one endpoint with different targets, because the difference between cordon and drain is exactly what an operator needs to be sure of before running either. Draining had to be fixed first to make ctl drain worth having. A drained replica was stopped on the next pass, which cuts in-flight requests — the thing draining exists to avoid. Now a node marked Draining has its replicas drained, the model falls below its desired count, a replacement is placed elsewhere, and the original is stopped only once the replacement is serving. A grace period bounds it, because draining the only node that can host a model would otherwise never finish and the node could never be taken out of service. Verified against a two-node cluster of real binaries: draining moved a replica to the surviving node and traffic kept returning 200 throughout. ctl logs is deliberately absent. It needs a request/response pair the agent protocol does not have, and the failure path already ships an engine log tail with every status report — so the case that matters most is covered, and reading a healthy shard's output on demand is not worth a protocol change yet. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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ilkerandClaude Opus 5
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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> |
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ilkerandClaude Opus 5
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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> |
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ilkerandClaude Opus 5
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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> |
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ilkerandClaude Opus 5
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c1b9ea1bc2 |
Phase 3 (3/3): wire the control plane to the router
CI / test (push) Successful in 50s
Ready replicas become router endpoints with no static configuration involved. Endpoints that survive an update keep their live state — inflight counts, breaker state, drain rate — so a replica that was already serving does not start from cold because another one moved. The sink is an interface, so when the router and control plane split into separate processes it becomes a watch stream and nothing above it changes. Phase 3's exit criterion now holds end to end. A node hosting a live replica is killed while four clients stream continuously; the control plane marks it unreachable, then lost, rebuilds the replica on a survivor and republishes. Across three runs ~370 requests completed with zero failures and no replica was left on the dead node. This proves the control logic, not the transport: the agent fleet is simulated and the real path still needs the stream. The race detector caught a genuine bug while this went in. startReplica read the replica's fields after publishing it to the map, and scaleUp walked replica pointers outside the lock; both raced with agent status reports, which arrive from another goroutine and mutate exactly those fields. Against the simulated fleet the reports came back fast enough to hit the window on every run. State is snapshotted under the lock now and those functions work from values. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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ilkerandClaude Opus 5
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f0134a2f95 |
Phase 3 (2/3): catalog and reconciler
CI / test (push) Successful in 24s
The desired-versus-actual loop, with a Dispatcher interface where the agent stream will go. The loop's logic is where the interesting failures live, not the transport, so it is tested against a fake dispatcher and a synthetic clock. - catalog: models, profiles, aliases, fallbacks, scaling bounds. Aliases and fallbacks resolve at load rather than at request time, because a typo in a fallback should stop a deployment instead of surfacing during the outage when the fallback is finally needed. The node/GPU/TP arithmetic is checked here too, so a bad profile fails at config load rather than minutes into loading. - reconciler: one replica placed per pass, since placement depends on what is already allocated and several from one snapshot would be handed the same GPUs. Workers start before rank 0: SGLang's ranks rendezvous and vLLM under Ray needs its workers attached before the head serves. - a failed shard fails the whole replica. The others are waiting on collectives that will never complete while holding GPUs, so every shard is stopped and the replica rebuilt, with a jittered exponential backoff carried on the model rather than on the replica that was just destroyed. - node expiry has two stages, Unreachable then Lost, deliberately far apart: a network blip must not tear down replicas that are still serving, and rebuilding a multi-node replica costs tens of minutes of model loading. - scale-down drains before stopping, so in-flight requests finish. The phase 3 exit criterion is half met. TestLostNodeMovesReplicas covers the reconciliation half end to end. The router continuing to serve throughout needs the EndpointSource wiring and the agent stream. Writing the tests caught a real property of the design worth recording: advancing the clock makes every node look silent, so placement correctly stops. The test harness now heartbeats nodes as it advances time, except where a node going silent is the point. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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ilkerandClaude Opus 5
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06672d1b85 |
Phase 3 (1/3): cluster inventory and placement
CI / test (push) Successful in 23s
The two hard constraints from plan §1.1 are enforced structurally rather than checked after the fact: there is no code path that can combine nodes from two fabrics, and only GPUs of the profile's class are ever considered. Getting either wrong produces a replica that starts, passes health checks, and then hangs or crawls under load — which looks like success until traffic arrives. - inventory: nodes, hardware, fabric attachments, allocations. A re-registering agent cannot clear an operator's cordon, since a cordon is usually in place because something is wrong with the node. A GPU with an ECC fault or another process on it is not free in any useful sense. Replicas are released whole, because they fail whole. - placement: highest-priority profile that fits, with every rejected candidate explained. "Unschedulable" on its own tells an operator nothing about which of six constraints bit. - bin packing fills partly used nodes first so whole nodes stay free for large models that cannot be split; multi-node replicas get the emptiest machines instead, being the least movable thing in the cluster. - NVLink-aware GPU selection keeps a tensor-parallel group inside one domain where the topology is known, falling back to lowest free indices otherwise. Property-based tests generate 400 random clusters and assert the invariants on every placement produced: one fabric per multi-node replica, only that fabric's HCAs per shard, one GPU class, no unhealthy or already-allocated GPU. The table-driven tests cover the cases someone thought of; these cover the rest. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |