comfy-api-proxy 0.1.0

Local proxy exposing the Comfy API v2 in front of a self-hosted ComfyUI instance.

comfy-api-proxy

A local service that puts the Comfy API v2 in front of a self-hosted ComfyUI instance. The same client SDK code that talks to Comfy Cloud can drive a ComfyUI on your own machine instead — and, since this proxy is Python + aiohttp (the same stack as ComfyUI core), the same adapter can later move into core itself. That's the "one contract, three surfaces" idea: Comfy Cloud, this proxy, and (eventually) ComfyUI core all speak the same /api/v2/ shape, so integrator code doesn't need to fork depending on where it's pointed.

Requirements & install

• Python 3.10+ (CI runs 3.10, 3.11, and 3.12 on every pull request).

• Install from PyPI:

  pip install comfy-api-proxy
  

Quickstart

Against a real ComfyUI

Point the proxy at an already-running ComfyUI and it serves /api/v2/* on its own port:

# Start in the background (defaults: ComfyUI at 127.0.0.1:8188, serve on :8189):
comfy-api-proxy start
comfy-api-proxy status
comfy-api-proxy stop

# Point it elsewhere / co-locate with ComfyUI to enable model-directory uploads:
comfy-api-proxy start --comfyui http://127.0.0.1:8188 --port 8189 \
  --comfyui-base-dir /path/to/ComfyUI

# Or run in the foreground (Ctrl+C to stop):
comfy-api-proxy run

No-GPU demo

demo/fake_comfyui.py is a stand-in ComfyUI — just enough of the native /prompt / /history / /queue / /view / /ws surface to run a workflow end to end without a GPU (or ComfyUI installed at all):

python demo/fake_comfyui.py &          # a stand-in ComfyUI on :8188
comfy-api-proxy &                      # the proxy on :8189
python demo/run_demo.py                # submit → wait → download

demo/run_demo.py drives the proxy through the real Python SDK (comfy_sdk.Comfy) — the same client code you'd point at Comfy Cloud — and imports it from a sibling checkout, so clone the SDK repo (see SDKs and the API contract below) next to this one before running the demo:

some-parent-dir/
├── comfy-api-proxy/   (this repo)
└── ComfyPythonSDK/

CI never depends on that checkout being present: the test suite (tests/test_smoke.py) drives the proxy's own HTTP surface directly with only the standard library, so pytest works with nothing but this repo installed.

The /api/v2/ surface

Wraps ComfyUI's native HTTP + WebSocket API one-to-one:

v2 operation	Backed by
POST /api/v2/jobs	Resolves any core/ASSET reference in the workflow to the filename ComfyUI expects, then POST /prompt
GET /api/v2/jobs/{id}	GET /history/{id} (+ /queue while queued/running) — the authoritative, pollable state
POST /api/v2/jobs/{id}/cancel	ComfyUI's atomic POST /api/jobs/{id}/cancel
GET /api/v2/jobs/{id}/events	Server-Sent Events, driven by ComfyUI's /ws (the only live signal ComfyUI exposes)
POST /api/v2/assets	Multipart upload; blake3-hashed and deduped locally; routed to ComfyUI's /upload/image for workflow inputs, or placed directly in a model directory (see below) for model weights
POST /api/v2/assets/from-hash, HEAD /api/v2/assets/by-hash/{hash}	Local hash index
GET /api/v2/assets/{id}, GET /api/v2/assets/{id}/content	Local index / ComfyUI /view, Range-capable

Poll-first, same as the canonical contract: GET /api/v2/jobs/{id} is always the source of truth for a job's state; the SSE stream (GET /api/v2/jobs/{id}/events) is a live convenience layered on top of it — a client that never opens it still sees the same state by polling. See Live events (SSE) below for what the stream carries and its concurrent-connection limit.

Model-file uploads (checkpoints/, loras/, vae/, ...)

ComfyUI's own /upload/image only understands input/output/temp — it has no endpoint for placing a file into a model directory. This proxy can do that itself, but only when it is co-located with ComfyUI (same host, sharing a filesystem) and started with --comfyui-base-dir pointing at the ComfyUI install root. Without that flag, model-directory uploads are rejected with a clear error; workflow-input uploads (images, etc.) work either way.

When enabled, a model upload must clear all of the following before a byte touches disk:

• safetensors-only, verified by parsing the file's own header (the length-prefixed JSON tensor index) — never a pickle/torch.load path.
• Allowlisted destination roots only — the real ComfyUI model directories (checkpoints, loras, vae, controlnet, ...). configs and custom_nodes are deliberately excluded even though ComfyUI itself has directories by those names, since one holds arbitrary YAML and the other arbitrary Python.
• No path traversal, including through a symlink — the resolved, real (symlink-followed) destination path must still land inside the configured model directory.
• Atomic, no-clobber writes — a temp file plus O_EXCL on the final destination, so two uploads can never race into a torn or silently overwritten file.

Once placed, the asset's file_path — and the value substituted for any core/ASSET reference to it in a submitted workflow — is the filename relative to the model-root directory (e.g. my_model.safetensors, not checkpoints/my_model.safetensors). That matches how ComfyUI's own combo widgets/loaders reference a model internally; a category-qualified path would be rejected as an unknown filename.

Live events (SSE)

GET /api/v2/jobs/{id}/events opens one WebSocket connection to ComfyUI, performs its feature_flags handshake, and translates the native progress/progress_state/preview/terminal messages into the v2 SSE event catalog (status, progress, preview, output), throttled to ~2 progress/preview events per second. If ComfyUI's WebSocket is unreachable, the stream falls back to polling /history so it still resolves to an authoritative terminal status rather than failing outright.

A proxy instance also caps concurrent event streams (8 by default, since each one holds open a ComfyUI WebSocket connection). Past that limit, a new stream request gets 429 too_many_streams with a Retry-After hint instead of queuing or degrading — GET /api/v2/jobs/{id} polling is always available regardless, and a slot frees up as soon as the stream it belongs to ends (the job finishes, or the client disconnects).

Security defaults

Everything here is on by default — no flags needed to get to the safe configuration:

• Binds to 127.0.0.1 only. Widening --host to a non-loopback address is refused (the process exits with an error) unless --token is set, or --allow-insecure-bind is passed to explicitly opt out of that guard.
• An optional static bearer token (--token) gates all of /api/v2/* when configured; unset by default, since a self-hosted single-user ComfyUI usually has nothing to authenticate against.
• A default-on origin-check middleware — ported from ComfyUI core's own create_origin_only_middleware — rejects cross-site browser requests even when nothing else is configured, closing the DNS-rebinding / drive-by-CSRF hole any unauthenticated localhost server is exposed to.
• Model-file uploads are safetensors-only, with path-traversal and symlink-escape guards (see Model-file uploads above) — and are rejected outright unless the proxy was started co-located with --comfyui-base-dir.

CLI reference

comfy-api-proxy --comfyui http://127.0.0.1:8188 --port 8189 [options]

Flag	Default	What it does
--comfyui	http://127.0.0.1:8188	Base URL of the self-hosted ComfyUI to proxy.
--host	127.0.0.1	Address to bind. Widening past loopback requires --token or --allow-insecure-bind (see Security defaults).
--port	8189	Port to serve the v2 API on.
--token	(unset)	Require Authorization: Bearer <token> on every /api/v2/* request.
--comfyui-base-dir	(unset)	Filesystem root of a co-located ComfyUI install. Required to enable direct model-directory placement of model-file uploads; without it, model uploads are rejected (workflow-input uploads still work).
--max-upload-mb	100	Max single-request upload size, in MB.
--allow-insecure-bind	false	Permit binding a non-loopback --host without a --token. Unsafe — exposes an unauthenticated proxy to the network.

SDKs and the API contract

Any real integration — and demo/run_demo.py — uses the same client SDKs Comfy Cloud users use, just pointed at this proxy's --host:--port instead of api.comfy.org / cloud.comfy.org:

• ComfyPythonSDK
• ComfyTypeScriptSDK

spec/openapi.yaml in this repo is a synced, filtered copy of that same Comfy API v2 contract — see spec/README.md for what "filtered" means, and Development below for how it's kept in sync.

Development

pip install -e ".[dev]"
ruff check .            # lint
ruff format --check .   # format check
mypy src/comfy_api_proxy   # type-check (lenient - see pyproject.toml)
pytest -v                # unit + end-to-end tests
python3 scripts/generate_models.py && git diff --exit-code src/comfy_api_proxy/schemas/_generated.py
                          # spec-drift check (also runs in CI)

These are exactly the checks CI runs (.github/workflows/ci.yml), each as its own job — lint/format, type-check, spec-drift, and test — with the test job running across Python 3.10, 3.11, and 3.12.

tests/test_smoke.py and tests/test_endpoints.py start the fake ComfyUI stand-in and the real proxy as subprocesses and drive both over plain HTTP (standard library only — no SDK, no third-party client, no dependency on another repo's credentials), covering upload → core/ASSET-reference → run → download, cancel, from-hash/by-hash, the SSE stream (including its concurrent-stream cap), and the model-placement security guards.

Keeping spec/openapi.yaml in sync

The vendored spec is generated, one-way (upstream → here), and never hand-edited. scripts/sync-spec.sh fetches the canonical spec from wherever it's passed (a local path or a URL), runs it through scripts/filter_openapi.py — which strips anything internal-only before a byte lands in this public repo — and writes the result to spec/openapi.yaml plus a spec/VERSION provenance pin. scripts/generate_models.py then regenerates the pydantic models (src/comfy_api_proxy/schemas/_generated.py) that tests/test_schema_conformance.py validates real handler responses against — those models are used only in tests, never on the request-handling hot path. CI's spec-drift job re-runs the generator and fails the build if the checked-in models don't match, so a spec sync without a regeneration gets caught immediately instead of drifting silently. See spec/README.md and docs/sync-workflow.md for the full design.

Scope

Implemented: submit (with core/ASSET resolution), poll, cancel, live SSE events, asset upload/download, from-hash/by-hash dedup, and guarded model-directory placement.

Known limitations:

• State is in-memory only. The asset index and job store live in memory (as does ComfyUI's own history), so all state is lost on restart. A job id or asset id issued before a restart no longer resolves afterward — this includes the HMAC-signed stateless output ids, since the signing secret is regenerated per process. A client that persists an id across a proxy restart must expect a 404; a durable store is a follow-up.
• Idempotency-Key dedup is in-memory. A reused key is rejected (422 idempotency_key_reuse — keys are single-use, no replay), but the claim set lives in the process and is cleared on restart, so a key reused across a proxy restart is not detected. A durable store is a follow-up.
• Uploads are not zero-copy. Large uploads are read fully into memory / a temp file rather than true streaming.