spark-control/docs/guides/fastapi-image.md

paths

paths
image/**

FastAPI image (image/)

Standalone FastAPI app (Python ≥3.11; ships on python:3.12-slim; UI on port 9999; vanilla HTML/CSS/JS, no framework). Python has no configured linter/formatter — match the style of the file you're editing.

Local dev (no StartOS)

cd image
python3 -m venv .venv && source .venv/bin/activate   # one-time
pip install -e .
export SPARK1_HOST=<ip> SPARK1_USER=<user> SPARK2_HOST=<ip> SPARK2_USER=<user> SSH_KEY_PATH=<private-key>
# Required outside the container — these default to paths under /data, which only exists in the image
# (missing REDACTION_MAP_DB crashes startup; missing CONNECTIVITY_LOG 500s /api/status):
export REDACTION_MAP_DB=/tmp/redaction_maps.db CONNECTIVITY_LOG=/tmp/connectivity.json
uvicorn app.server:app --host 0.0.0.0 --port 9999 --reload

Other env vars: BIND_PORT, MODELS_YAML, SSH_DIR, SSH_KNOWN_HOSTS, MODELS_OVERRIDES, SERVICES_OVERRIDES.

Tests

Two kinds, both run with the image/.venv interpreter (system python3 has no deps):

• pytest unit suite — offline, pure functions, no cluster. .venv/bin/python -m pytest from image/. Lives in image/tests/; currently covers build_launch_command (incl. the shell-injection / shlex round-trip invariant) and the transcript↔diarizer label-merge (_merge_words_with_speakers). Install the test dep once with pip install -e '.[dev]'. Add new pure-function coverage here.
• Standalone scripts — the redaction suites and the live-cluster audio e2e are run directly (not via pytest). See the redaction and audio rules.

Conventions

• Pydantic request models go at module scope, never inside a build_router() body (FastAPI silently 422s otherwise).
• New external-facing endpoints get documented in docs/ (AUDIO_API.md, EMBEDDINGS.md, REDACTION_GATEWAY.md) and noted in release notes.
• SSH-input safety: any user-supplied value that reaches an SSH command on the Sparks MUST go through app/shellsafe.py — validate against a whitelist at the API boundary, then quote_arg/quote_args (shlex.quote) at the sink. Never raw f-string a user value into a command string. Existing sinks: models.build_launch_command, download, nim, services; disk.py keeps its own _SAFE_DIRNAME because it needs $HOME to expand server-side. The vLLM pre-flight (validate.py) relies on shlex.split cleanly reversing this quoting — preserve that invariant.
• CSRF / same-origin: state-mutating control endpoints are guarded by the csrf_guard middleware in server.py (rejects requests whose Origin/Referer host ≠ the served host). A new endpoint meant to be called cross-origin by downstream apps (a proxy/data endpoint) must be added to _CSRF_EXEMPT_PREFIXES, or browser POSTs from those apps will 403. No app-layer token auth by design (LAN/VPN-only; would break consumers).

Layout

• image/app/server.py — FastAPI entry; routers live in sibling modules (audio_proxy.py, llm_proxy.py, embeddings_proxy.py, redaction_gateway.py, swap.py, health.py, deep_health.py, connectivity.py, …).
• image/app/static/ — the dashboard UI.
• image/models.yaml — vLLM model catalog bundled into the image.
• image/spark_embed/ — Dockerfile + app for the embeddings container; built ON a Spark (ARM64, NGC PyTorch base — see the audio/cluster rule for NGC torch-pinning caveats).