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LocalAI/docs/content/features
Ettore Di Giacinto 49b3d22974 feat(worker): serve the control plane over the tunnel, not over NATS
Ten NATS subscriptions on the worker become ten HTTP routes under
/v1/control/, served on the loopback HTTP server the worker already runs
and reached only through the tunnel's existing `http` stream tag.

The carrier is the tag that already exists rather than a new one. A new
tag would have had to invent correlation, per-request deadlines,
unbounded payloads and a progress stream, and each of those is a place
this branch has already put a defect. It would also have added a fifth
entry to the worker's stream-refusal vocabulary, which decides what a
frontend reaps on and took eight fixes to settle. Riding `http` means a
control RPC to a worker another replica holds takes the same relay the
inference path takes, which is the path that has been measured.

The request and reply DTOs are untouched, so a body on a control route
is byte-for-byte what the corresponding subject carried. No subject was
deleted: agent workers still subscribe to nodes.<id>.backend.stop.

Install and upgrade stream. They answer application/x-ndjson: zero or
more {"progress":...} lines carrying the same event the per-op NATS
subject carried, then exactly one {"reply":...} line, always last. That
deletes the 8000-byte notification cap structurally instead of
reproducing it on a new carrier: a progress line is written into the
response the caller is already reading, so there is nothing to size and
no subscribe-before-request window. The debouncer is shared with the
NATS publisher rather than forked, so the ~4/s tick bound is one fact.

A verb's own failure is a 200 with Error set, never a 5xx. The frontend
maps a transport failure onto "no route to that worker", which nothing
may act on, and the worker's answer onto evidence a reap guard may act
on; answering 500 for a failed install would put the worker's verdict
in the bucket reserved for a broken link. Only a request that could not
be read or routed is non-2xx.

Control RPCs carry the caller's budget. r.Context() replaces four
context.Background() calls at the gallery-install sites, and the one
pre-existing fixed timeout on model.unload is now derived from the
caller's context so a shorter budget is honoured. No timeout is invented.

The inner `go func()` in the install and upgrade handlers is deleted
rather than nested: it existed because one subscription served every
install, and over HTTP each request already has its own goroutine.
Per-backend serialization stays lockBackend, which is what actually
prevented two requests racing the gallery directory.

Bounds against a boundary the worker now serves: every body is capped at
8 MiB before any decode; the 404 echoes at most 128 bytes of the request
path, cut on a rune boundary so a half rune cannot travel downstream as
a replacement character; non-POST is refused before the body is read so
a probe cannot fire a command; the streaming responses set nosniff.

The routes mount through nodes.AuthenticatedRoutes, which hands the
registrar a private mux and puts the whole prefix behind the same
constant-time bearer check as the file routes. The worker's HTTP server
now takes the supervisor as a required parameter, so there is no way to
start it without the control plane mounted.

Assisted-by: Claude Opus 5 [claude-code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
2026-09-02 15:51:58 +00:00
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