feat: flow runtime on LFX with tests
- LfxClient (upload/run/info/delete, typed errors, serve-key auth) - Flows API: CRUD, versions, deploy, sync run, SSE stream proxy, runs - Approvals callback endpoint (flow terminal-state contract) - Runner: envelope in, status from approval side-effect (no interrupts) - Fixture generator (lfx serializers) + simple_rule/approval_handoff fixtures verified against real lfx serve - 14 tests green (real LFX subprocess + live uvicorn callback server)
This commit is contained in:
Jonas Miederer
parent
e178ae406d
commit
96c0da33c7
15 changed files with 5070 additions and 5 deletions
311
backend/app/flows/api.py
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311
backend/app/flows/api.py
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"""Flows + approvals HTTP API."""
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from __future__ import annotations
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import json
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from collections.abc import AsyncIterator, Iterator
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from uuid import UUID
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import httpx
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from fastapi import APIRouter, Depends, HTTPException, Query
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from fastapi.responses import StreamingResponse
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from sqlmodel import Session
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from app.db import get_engine, get_session
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from app.settings import settings
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from . import runner, store
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from .lfx_client import (
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LfxClient,
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LfxConflict,
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LfxError,
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LfxInvalidFlow,
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LfxNotFound,
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LfxRunFailed,
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LfxUnavailable,
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)
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from .schemas import (
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ApprovalCreate,
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ApprovalRead,
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FlowDefinitionCreate,
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FlowDefinitionRead,
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FlowVersionCreate,
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FlowVersionRead,
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RunRead,
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RunRequest,
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)
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flows_router = APIRouter(prefix="/api/flows", tags=["flows"])
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approvals_router = APIRouter(prefix="/api/approvals", tags=["approvals"])
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def get_db() -> Iterator[Session]:
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yield from get_session()
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def get_lfx() -> LfxClient:
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return LfxClient(settings.lfx_url, api_key=settings.lfx_api_key or None)
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def _read_definition(d) -> FlowDefinitionRead:
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return FlowDefinitionRead(
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id=d.id,
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name=d.name,
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description=d.description,
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status=d.status,
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continuation_flow_id=d.continuation_flow_id,
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created_at=d.created_at,
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)
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def _read_version(v) -> FlowVersionRead:
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return FlowVersionRead(
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id=v.id,
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flow_id=v.flow_id,
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version_no=v.version_no,
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langflow_json=v.langflow_json,
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lfx_flow_id=v.lfx_flow_id,
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deployed_at=v.deployed_at,
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author=v.author,
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created_at=v.created_at,
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)
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def _read_run(r) -> RunRead:
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return RunRead(
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id=r.id,
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version_id=r.version_id,
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tenant_id=r.tenant_id,
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status=r.status,
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input=r.input,
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output=r.output,
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session_id=r.session_id,
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created_at=r.created_at,
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finished_at=r.finished_at,
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)
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def _read_task(t) -> ApprovalRead:
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return ApprovalRead(
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id=t.id,
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run_id=t.run_id,
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version_id=t.version_id,
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tenant_id=t.tenant_id,
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title=t.title,
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payload=t.payload,
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continuation_flow_id=t.continuation_flow_id,
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approver=t.approver,
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status=t.status,
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decision_note=t.decision_note,
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created_at=t.created_at,
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decided_at=t.decided_at,
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)
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@flows_router.post("", response_model=FlowDefinitionRead, status_code=201)
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def create_flow(data: FlowDefinitionCreate, session: Session = Depends(get_db)):
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try:
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return _read_definition(store.create_definition(session, data))
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except store.ConflictError as exc:
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raise HTTPException(status_code=409, detail=str(exc)) from exc
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except store.InvalidError as exc:
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raise HTTPException(status_code=422, detail=str(exc)) from exc
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@flows_router.get("", response_model=list[FlowDefinitionRead])
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def list_flows(session: Session = Depends(get_db)):
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return [_read_definition(d) for d in store.list_definitions(session)]
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@flows_router.get("/{flow_id}", response_model=FlowDefinitionRead)
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def get_flow(flow_id: UUID, session: Session = Depends(get_db)):
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try:
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return _read_definition(store.get_definition(session, flow_id))
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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@flows_router.post(
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"/{flow_id}/versions", response_model=FlowVersionRead, status_code=201
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)
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def create_version(
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flow_id: UUID, data: FlowVersionCreate, session: Session = Depends(get_db)
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):
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try:
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return _read_version(store.create_version(session, flow_id, data))
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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except store.InvalidError as exc:
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raise HTTPException(status_code=422, detail=str(exc)) from exc
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@flows_router.get("/{flow_id}/versions", response_model=list[FlowVersionRead])
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def list_versions(flow_id: UUID, session: Session = Depends(get_db)):
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try:
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return [_read_version(v) for v in store.list_versions(session, flow_id)]
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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@flows_router.post(
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"/{flow_id}/versions/{version_no}/deploy", response_model=FlowVersionRead
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)
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async def deploy_version(
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flow_id: UUID,
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version_no: int,
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session: Session = Depends(get_db),
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lfx: LfxClient = Depends(get_lfx),
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):
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try:
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version = store.get_version_by_no(session, flow_id, version_no)
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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try:
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uploaded = await lfx.upload_flow(
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version.langflow_json, flow_id=str(version.id), replace=True
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)
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except LfxInvalidFlow as exc:
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raise HTTPException(status_code=422, detail=str(exc)) from exc
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except LfxConflict as exc:
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raise HTTPException(status_code=409, detail=str(exc)) from exc
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except LfxUnavailable as exc:
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raise HTTPException(status_code=503, detail=str(exc)) from exc
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except LfxError as exc:
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raise HTTPException(status_code=502, detail=str(exc)) from exc
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return _read_version(store.mark_deployed(session, version, uploaded.id))
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def _resolve_version(session: Session, flow_id: UUID, version_no: int | None):
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if version_no is not None:
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return store.get_version_by_no(session, flow_id, version_no)
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return store.get_latest_deployed_version(session, flow_id)
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@flows_router.post("/{flow_id}/run", response_model=RunRead)
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async def run_flow(
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flow_id: UUID,
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data: RunRequest,
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stream: bool = Query(default=False),
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session: Session = Depends(get_db),
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lfx: LfxClient = Depends(get_lfx),
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):
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try:
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version = _resolve_version(session, flow_id, data.version_no)
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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except store.InvalidError as exc:
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raise HTTPException(status_code=422, detail=str(exc)) from exc
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if stream:
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return await _run_stream(session, lfx, version, data)
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try:
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run = await runner.execute_run(
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session,
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lfx,
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version,
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payload=data.input,
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tenant_id=data.tenant_id,
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session_id=data.session_id,
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callback_base_url=data.callback_base_url or settings.callback_base_url,
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continuation_flow_id=data.continuation_flow_id,
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)
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except LfxNotFound as exc:
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raise HTTPException(status_code=502, detail=f"LFX drift: {exc}") from exc
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except LfxUnavailable as exc:
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raise HTTPException(status_code=503, detail=str(exc)) from exc
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except LfxError as exc:
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raise HTTPException(status_code=502, detail=str(exc)) from exc
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return _read_run(run)
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async def _run_stream(session: Session, lfx: LfxClient, version, data: RunRequest):
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if not version.lfx_flow_id:
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raise HTTPException(
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status_code=422, detail=f"version {version.id} is not deployed to LFX"
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)
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run = store.create_run(
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session,
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version,
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input=data.input,
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tenant_id=data.tenant_id,
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session_id=data.session_id,
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)
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envelope = runner.build_envelope(
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payload=data.input,
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run_id=run.id,
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callback_base_url=data.callback_base_url or settings.callback_base_url,
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continuation_flow_id=data.continuation_flow_id,
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)
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run_id = run.id
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lfx_flow_id = version.lfx_flow_id
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session_id = data.session_id or str(run.id)
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async def event_gen() -> AsyncIterator[str]:
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yield f"event: run\ndata: {json.dumps({'run_id': str(run_id)})}\n\n"
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try:
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async with httpx.AsyncClient(
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base_url=lfx.base_url, timeout=lfx.timeout, headers=lfx._headers()
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) as client:
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async with client.stream(
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"POST",
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f"/flows/{lfx_flow_id}/stream",
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json={"input_value": envelope, "session_id": session_id},
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) as response:
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if response.status_code == 404:
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raise LfxNotFound(f"flow {lfx_flow_id} unknown to LFX")
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response.raise_for_status()
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async for chunk in response.aiter_text():
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yield chunk
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except (LfxNotFound, httpx.HTTPError) as exc:
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yield f"event: error\ndata: {json.dumps({'error': str(exc)})}\n\n"
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# Finalize from a fresh session: the request session may be closed.
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with Session(get_engine()) as fresh:
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try:
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fresh_run = store.get_run(fresh, run_id)
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status = (
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"pending_approval"
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if runner._task_exists(fresh, run_id)
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else "completed"
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)
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store.set_run_result(fresh, fresh_run, status, {"streamed": True})
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except store.NotFoundError:
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status = "failed"
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yield f"event: run_finished\ndata: {json.dumps({'run_id': str(run_id), 'status': status})}\n\n"
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return StreamingResponse(event_gen(), media_type="text/event-stream")
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@flows_router.get("/{flow_id}/runs", response_model=list[RunRead])
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def list_runs(flow_id: UUID, session: Session = Depends(get_db)):
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try:
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return [_read_run(r) for r in store.list_runs(session, flow_id)]
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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@flows_router.get("/runs/{run_id}", response_model=RunRead)
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def get_run(run_id: UUID, session: Session = Depends(get_db)):
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try:
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return _read_run(store.get_run(session, run_id))
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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@approvals_router.post("", response_model=ApprovalRead, status_code=201)
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def create_approval(data: ApprovalCreate, session: Session = Depends(get_db)):
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"""Flow callback contract: report a terminal approval state for a run."""
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try:
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return _read_task(store.create_approval_task(session, data))
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except store.NotFoundError as exc:
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raise HTTPException(status_code=404, detail=str(exc)) from exc
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except store.ConflictError as exc:
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raise HTTPException(status_code=409, detail=str(exc)) from exc
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except store.InvalidError as exc:
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raise HTTPException(status_code=422, detail=str(exc)) from exc
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@approvals_router.get("", response_model=list[ApprovalRead])
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def list_approvals(
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tenant_id: str | None = Query(default=None),
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session: Session = Depends(get_db),
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):
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return [_read_task(t) for t in store.list_approval_tasks(session, tenant_id)]
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