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382"""HTTP client for docling-serve.
Wraps docling-serve's ``/v1/convert/file`` endpoint with connection pooling,
circuit breaker, and retry logic. The client is created at app startup and
closed at shutdown via the module-level lifecycle helpers.
When docling runs behind an internal ALB (PRD-1), cold starts produce 503s
and ConnectErrors while EC2 instances spin up. The circuit breaker is tuned
with a high threshold (10) and long timeout (360s) to tolerate this.
Usage::
from src.services.docling_serve_client import get_docling_client
client = get_docling_client()
response = await client.convert(file_content, "syllabus.pdf")
"""
from __future__ import annotations
import asyncio
import logging
from collections.abc import Callable
from typing import Any
import httpx
from pydantic import BaseModel, Field
from src.utils.circuit_breaker import CircuitBreaker
logger = logging.getLogger(__name__)
# ---------------------------------------------------------------------------
# Response model
# ---------------------------------------------------------------------------
class DoclingServeResponse(BaseModel):
"""Parsed response from docling-serve ``/v1/convert/file``."""
md_content: str = ""
json_content: dict[str, Any] = Field(default_factory=dict)
status: str = "unknown"
processing_time: float = 0.0
errors: list[str] = Field(default_factory=list)
# ---------------------------------------------------------------------------
# Client
# ---------------------------------------------------------------------------
# Circuit breaker tuned for decoupled docling behind ALB:
# - threshold=10: tolerate cold-start 503s before tripping
# - timeout=360s: EC2 Spot + model loading can take ~3-5 min
_CIRCUIT_BREAKER = CircuitBreaker(
"docling-serve",
failure_threshold=10,
timeout=360.0,
)
# Limit concurrent docling-serve calls to prevent OOM (~1-2GB per PDF)
_DOCLING_SEMAPHORE = asyncio.Semaphore(int(__import__("os").environ.get("DOCLING_MAX_CONCURRENT", "2")))
class DoclingServeClient:
"""Async HTTP client for docling-serve."""
def __init__(self, base_url: str, timeout: float = 300.0) -> None:
self._base_url = base_url.rstrip("/")
self._client = httpx.AsyncClient(
base_url=self._base_url,
timeout=httpx.Timeout(timeout, connect=10.0),
limits=httpx.Limits(max_connections=10, max_keepalive_connections=5),
)
# -- conversion ---------------------------------------------------------
async def convert(
self,
file_content: bytes,
filename: str,
*,
do_ocr: bool = False,
force_ocr: bool = False,
ocr_engine: str = "easyocr",
ocr_lang: list[str] | None = None,
do_table_structure: bool = True,
include_images: bool = True,
images_scale: float = 2.0,
md_page_break_placeholder: str = "<!-- PAGE_BREAK -->",
image_export_mode: str = "placeholder",
max_retries: int = 2,
timeout: float | None = None,
on_cold_start: Callable[[], None] | None = None,
) -> DoclingServeResponse:
"""Convert a PDF via docling-serve with retry and circuit breaker.
Args:
file_content: Raw PDF bytes.
filename: Original filename (sent as multipart name).
do_ocr: Enable OCR processing.
force_ocr: Force OCR even when text is detected.
ocr_engine: OCR engine name (``easyocr``, ``tesseract``, etc.).
ocr_lang: OCR language codes (EasyOCR format, e.g. ``["en"]``).
do_table_structure: Extract table structure.
include_images: Extract images from the document.
images_scale: Scale factor for extracted images.
md_page_break_placeholder: Marker inserted between pages in MD.
image_export_mode: How images appear in output (``embedded`` / ``placeholder``).
max_retries: Maximum retry attempts on transient errors.
timeout: Per-request timeout override (seconds). When set,
overrides the client-level timeout for this conversion only.
Useful for OCR which is significantly slower than text extraction.
Returns:
Parsed :class:`DoclingServeResponse`.
Raises:
CircuitBreakerOpenError: If the circuit breaker is open.
httpx.HTTPStatusError: On non-retryable HTTP errors.
RuntimeError: If all retries are exhausted.
"""
# Fail fast if circuit breaker is open (before acquiring semaphore)
_CIRCUIT_BREAKER.check_state()
async with _DOCLING_SEMAPHORE:
return await self._convert_with_retry(
file_content,
filename,
do_ocr=do_ocr,
force_ocr=force_ocr,
ocr_engine=ocr_engine,
ocr_lang=ocr_lang or [],
do_table_structure=do_table_structure,
include_images=include_images,
images_scale=images_scale,
md_page_break_placeholder=md_page_break_placeholder,
image_export_mode=image_export_mode,
max_retries=max_retries,
timeout=timeout,
on_cold_start=on_cold_start,
)
async def _convert_with_retry(
self,
file_content: bytes,
filename: str,
*,
do_ocr: bool,
force_ocr: bool,
ocr_engine: str,
ocr_lang: list[str],
do_table_structure: bool,
include_images: bool,
images_scale: float,
md_page_break_placeholder: str,
image_export_mode: str,
max_retries: int,
timeout: float | None = None,
on_cold_start: Callable[[], None] | None = None,
) -> DoclingServeResponse:
"""Inner retry loop (runs inside the concurrency semaphore)."""
last_exc: Exception | None = None
for attempt in range(1, max_retries + 2): # +2 because first attempt is not a retry
try:
response = await self._do_convert(
file_content,
filename,
do_ocr=do_ocr,
force_ocr=force_ocr,
ocr_engine=ocr_engine,
ocr_lang=ocr_lang,
do_table_structure=do_table_structure,
include_images=include_images,
images_scale=images_scale,
md_page_break_placeholder=md_page_break_placeholder,
image_export_mode=image_export_mode,
timeout=timeout,
)
_CIRCUIT_BREAKER.record_success()
return response
except (httpx.RemoteProtocolError, httpx.ConnectError) as exc:
# Server crashed (OOM) or unreachable (cold start / ALB no targets)
last_exc = exc
_CIRCUIT_BREAKER.record_failure()
if attempt <= max_retries:
logger.warning(
"docling-serve unreachable (attempt %d/%d): %s. Waiting for healthy...",
attempt,
max_retries + 1,
type(exc).__name__,
)
if on_cold_start is not None:
on_cold_start()
on_cold_start = None
await self._wait_for_healthy(timeout=300.0)
continue
raise
except (httpx.TimeoutException, TimeoutError) as exc:
last_exc = exc
_CIRCUIT_BREAKER.record_failure()
if attempt <= max_retries:
delay = min(2.0 ** (attempt - 1), 8.0)
logger.warning(
"docling-serve timeout (attempt %d/%d): %s. Retrying in %.1fs",
attempt,
max_retries + 1,
exc,
delay,
)
await asyncio.sleep(delay)
continue
raise
except httpx.HTTPStatusError as exc:
last_exc = exc
status_code = exc.response.status_code
if status_code == 503:
# ALB has no healthy targets — cold start
_CIRCUIT_BREAKER.record_failure()
if attempt <= max_retries:
logger.warning(
"docling-serve 503 (cold start?), waiting for healthy...",
)
if on_cold_start is not None:
on_cold_start()
on_cold_start = None # fire only once
await self._wait_for_healthy(timeout=300.0)
continue
raise
elif status_code == 504:
# Document too slow — not a service failure, no retry
logger.warning(
"docling-serve 504 timeout for '%s' — document too large/complex",
filename,
)
raise
elif status_code >= 500:
_CIRCUIT_BREAKER.record_failure()
if attempt <= max_retries:
delay = min(2.0 ** (attempt - 1), 8.0)
logger.warning(
"docling-serve %d error (attempt %d/%d). Retrying in %.1fs",
status_code,
attempt,
max_retries + 1,
delay,
)
await asyncio.sleep(delay)
continue
raise
# Non-retryable (4xx, etc.)
raise
# Should not reach here, but for type safety
if last_exc:
raise last_exc
raise RuntimeError("docling-serve: unexpected retry loop exit")
async def _wait_for_healthy(self, timeout: float = 300.0) -> None:
"""Poll docling-serve health endpoint until it responds or timeout."""
deadline = asyncio.get_event_loop().time() + timeout
interval = 3.0
while asyncio.get_event_loop().time() < deadline:
await asyncio.sleep(interval)
if await self.check_health():
logger.info("docling-serve is healthy again")
return
logger.warning("docling-serve did not recover within %.0fs", timeout)
async def _do_convert(
self,
file_content: bytes,
filename: str,
*,
do_ocr: bool,
force_ocr: bool,
ocr_engine: str,
ocr_lang: list[str],
do_table_structure: bool,
include_images: bool,
images_scale: float,
md_page_break_placeholder: str,
image_export_mode: str,
timeout: float | None = None,
) -> DoclingServeResponse:
"""Send the actual HTTP request to docling-serve."""
# httpx 0.28+ requires all multipart fields in `files` param when using
# AsyncClient — mixing `files` and `data` creates a SyncByteStream which
# raises RuntimeError. Form fields use ``(None, value)`` tuples.
fields: list[tuple[str, tuple[str | None, str | bytes, str] | tuple[None, str]]] = [
("files", (filename, file_content, "application/pdf")),
("to_formats", (None, "md")),
("to_formats", (None, "json")),
("image_export_mode", (None, image_export_mode)),
("do_ocr", (None, str(do_ocr).lower())),
("force_ocr", (None, str(force_ocr).lower())),
("ocr_engine", (None, ocr_engine)),
("do_table_structure", (None, str(do_table_structure).lower())),
("include_images", (None, str(include_images).lower())),
("images_scale", (None, str(images_scale))),
("md_page_break_placeholder", (None, md_page_break_placeholder)),
]
for lang in ocr_lang:
fields.append(("ocr_lang", (None, lang)))
request_kwargs: dict = {"files": fields}
if timeout is not None:
request_kwargs["timeout"] = httpx.Timeout(timeout, connect=10.0)
resp = await self._client.post("/v1/convert/file", **request_kwargs)
resp.raise_for_status()
body = resp.json()
# Parse the response envelope
doc = body.get("document", {})
return DoclingServeResponse(
md_content=doc.get("md_content", ""),
json_content=doc.get("json_content", {}),
status=body.get("status", "unknown"),
processing_time=body.get("processing_time", 0.0),
errors=body.get("errors", []),
)
# -- health -------------------------------------------------------------
async def check_health(self) -> bool:
"""Check if docling-serve is healthy.
Returns:
``True`` if the service responds to ``/health``, ``False`` otherwise.
"""
try:
resp = await self._client.get("/health")
return resp.status_code == 200
except Exception:
return False
# -- lifecycle ----------------------------------------------------------
async def close(self) -> None:
"""Close the underlying HTTP connection pool."""
await self._client.aclose()
# ---------------------------------------------------------------------------
# Module-level lifecycle helpers
# ---------------------------------------------------------------------------
_client: DoclingServeClient | None = None
def init_docling_client(base_url: str, timeout: float = 120.0) -> DoclingServeClient:
"""Create the module-level docling-serve client (call at app startup)."""
global _client # noqa: PLW0603
_client = DoclingServeClient(base_url, timeout)
logger.info("Docling-serve client initialized: %s (timeout=%.0fs)", base_url, timeout)
return _client
def get_docling_client() -> DoclingServeClient:
"""Return the module-level client, raising if not initialized."""
if _client is None:
raise RuntimeError(
"Docling-serve client not initialized. Call init_docling_client() at startup."
)
return _client
async def close_docling_client() -> None:
"""Close the module-level client (call at app shutdown)."""
global _client # noqa: PLW0603
if _client is not None:
await _client.close()
_client = None
logger.info("Docling-serve client closed")
def reset_docling_circuit_breaker() -> None:
"""Reset the circuit breaker (for testing)."""
_CIRCUIT_BREAKER.reset()