Ilker ManapandClaude Opus 5
b40bc481cf
The mirror was a directory and a discipline written down in a README. This makes the three operations that matter into commands, on the mirror host, where `llmgw keys` already sets the precedent of operator tooling that works on files rather than through the API. The gateway still never writes to the mirror. That property was chosen deliberately — a mirror writable by the thing reading from it is a way to replace a model with one every node then fetches without complaint — and a person running a command does not take it away. `serve` states it rather than inheriting it, so a handler added later cannot quietly make the mirror writable. `add` downloads to a temporary name and renames, for the reason the agent's fetcher does: a mirror is copied to every node, so a partial file here is a partial file everywhere. It verifies the length the server promised, reports a checksum — the mirror is the one place a corrupt file reaches every node rather than being caught once — and refuses to replace an existing version, which is the whole point of the layout. `unused` refuses to answer when it cannot read the catalog. An empty catalog and an unreachable one produce the same list, everything, and the obvious next step after that list is deletion. It compares by path rather than by spelling, because a base typed with a different scheme or a trailing slash would otherwise report a file in use as unused. `remove` checks the catalog first and says to retire the entry before deleting the file, because a node that has to refetch a deleted file cannot, and that failure arrives later, on the node, looking like something else. Verified end to end: Range requests answer 206, which is what makes an interrupted fetch on a node resume; writes answer 405; a traversal attempt answers 404. Note: internal/agent/supervisor's TestSidecarRunsBeforeEngine fails under full suite load on main as well as here — it asserts that one shell's echo lands before another's, which the supervisor does not promise. Everything else passes. Left alone rather than fixed in a commit about mirrors. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
llmgw
A single-binary LLM gateway for clusters with multiple InfiniBand fabrics and heterogeneous GPUs.
It serves LLMs running on your own GPU servers (vLLM / SGLang) behind one OpenAI-compatible endpoint. Design document: llmgw-plan.md.
Getting started
Starting from nothing — no packages installed, no drivers, no nodes — follow docs/install.md: it builds a control plane, adds a node and serves a model, and says plainly which parts llmgw does not install for you.
| Guide | For |
|---|---|
| docs/install.md | Standing up a cluster from scratch |
| docs/node-onboarding.md | Adding nodes to one that exists |
| docs/onboarding.md | Giving people accounts and keys |
Status
Releases track the roadmap phases; see CHANGELOG.md.
| Version | Phase | Scope | State |
|---|---|---|---|
| v0.1.0 | 0 | Skeleton and sim-engine | released |
| v0.2.0 | 1 | Static router (filter/score/pick, streaming proxy) | released |
| v0.3.0 | 1.5 | Admission control (priority bands) | released |
| v0.4.0 | 2 | Agent: GPU/IB discovery, engine supervision | released |
| v0.5.0 | 3 | Control plane: catalog, placement, reconciler, ctl | released |
| v0.6.0 | 4 | Multi-node placement and fabric awareness | released |
| v0.7.0 | — | Conversations, agent memory, disk management | released |
| v0.8.0 | — | PostgreSQL, leader election, agent failover | released |
| v1.0.0 | 5 | Tenancy, prefix affinity, benchmarking | planned |
As of v0.6.0 a cluster runs unattended: agents report their hardware, the control plane places replicas — including ones larger than a single machine — models load when someone asks for them and stop when nobody does, and keys, budgets and rate limits decide who may use any of it.
Before v1.0.0: tracing, reference documentation, and filtering on ctl nodes
and ctl replicas for fleets too large to read a whole table of. Two items
that were on this list are not gaps: a model falls through to its fallbacks
when there is no capacity as well as when a budget is spent, and routing
profiles are chosen by the key rather than by a request header on purpose —
a header would let any client promote itself into the top priority band.
One thing is worth saying plainly: multi-node replicas are proven on a simulated cluster and on real hardware without a fabric. The InfiniBand, NVML and NCCL paths are written against the formats and failure modes those tools actually have, but they have not yet run on a machine that has them.
Documentation
- docs/install.md — installing from nothing: control plane, nodes, engines, weights, first request
- docs/quickstart.md — the short path
- docs/choosing-models.md — which models to run, how many of each, and where the weights should live
- docs/data.md — what llmgw stores, what it does not, and what leaves the machine; written for a security review
- docs/reference.md — every configuration key, generated from the structs and checked by a test, so it cannot describe a setting that does not exist or miss one that does
- deploy/mirror/ — a model mirror, which is the cheapest and most useful thing to build around llmgw
- deploy/ha/ — running two control planes, and the one health check that has to be right
- docs/node-onboarding.md, docs/onboarding.md — adding machines, and adding people
Building
make build # bin/llmgw
make test # unit tests
make race # with the race detector
Operating a cluster
llmgw ctl nodes # capacity, health, what is running where
llmgw ctl models # catalog and replica counts
llmgw ctl replicas --model llama # replicas and their shards
llmgw ctl explain-placement llama # why a model has not been placed
llmgw ctl drain gpu-a-01 # move work off a node, one replica at a time
llmgw ctl cordon gpu-a-01 # stop new placement, leave what runs
ctl talks to the admin port (:9090 by default), not the client-facing one.
Add --json to any command for machine-readable output.
explain-placement is the one worth knowing about: "unschedulable" on its own
says nothing about which of six constraints bit, so it prints every candidate
considered and the reason it was rejected.
Running the router
# Two fake engines and a router in front of them.
./bin/llmgw sim-engine --listen :8001 --model llama &
./bin/llmgw sim-engine --listen :8002 --model llama &
./bin/llmgw server \
--endpoint e1=http://127.0.0.1:8001=llama \
--endpoint e2=http://127.0.0.1:8002=llama
curl -N localhost:8080/v1/chat/completions \
-H 'content-type: application/json' \
-H 'x-session-id: demo' \
-d '{"model":"llama","messages":[{"role":"user","content":"hello"}],"stream":true}'
For anything real use a config file; deploy/examples/server.yaml
is commented throughout. Metrics, health and pprof are on the admin port (:9090
by default), deliberately separate from the client-facing one.
Requests carry a priority band (x-llmgw-band). Under load, low bands wait at
the gateway while high bands keep flowing, so the cluster degrades from the
bottom up instead of everywhere at once. Measured effect: interactive p99 stays
within 1.24x of idle while 500 concurrent batch requests run, against 58x with
admission off.
Routing profiles select how endpoints are scored: chat favours session
affinity, batch favours the shortest queue, long-context favours free KV
cache. Pick one per model in the config, or per request with the
x-llmgw-profile header.
sim-engine
Simulates the inference-engine behaviours the router cares about, so the router can be developed and tested without GPUs. What it models:
- continuous batching (bounded number of concurrent sequences)
- KV cache block accounting, queueing once blocks run out (head-of-line blocking included)
- automatic prefix caching (chained block hashes plus an LRU) and its effect on time to first token
- per-token latency growing with batch size
- dropping a request and freeing its blocks when the client disconnects
/metricsusing vLLM's metric names
./bin/llmgw sim-engine --listen :8000 --model llama-3.3-70b
curl -N localhost:8000/v1/chat/completions \
-H 'content-type: application/json' \
-d '{"messages":[{"role":"user","content":"hello"}],"max_tokens":8,"stream":true}'
Tune load and latency behaviour with --max-num-seqs, --num-gpu-blocks,
--prefill-tps, --decode-tps, --batch-contention and
--prefix-cache-blocks. For chaos testing use --fail-rate, and --seed for
deterministic runs.
The engine metric contract
For the router to make routing decisions an engine must expose these three metrics (plan §7.6). sim-engine publishes them under vLLM's real names:
vllm:num_requests_running
vllm:num_requests_waiting
vllm:kv_cache_usage_perc
Adding support for a new engine means satisfying that contract. Metric names drift between versions, so the name mapping is configurable.
Module path
gitea.mynodes.xyz/ilker/llmgw. To change it:
make rename NEW=git.example.com/team/llmgw
Language
Code, comments, tests, commit messages and documentation are in English.