decomposer: generate deliverable files for Define the service contract and project architecture for the FastAPI endpoint monitoring service.; Implement the typed monitor CRUD API and concurrency-safe in-memory state according to the service design.; Implement secure on-demand endpoint checks with status updates, latency measurement, robust error handling, and redacted structured logs.; Add operational API endpoints and environment-driven runtime configuration to the monitoring service.; Create automated tests for the monitoring service.; Package the service with Docker and developer documentation.; Validate the complete project.

app/main.py

@@ -1,117 +1,101 @@
 from contextlib import asynccontextmanager
-from datetime import UTC, datetime
+from typing import AsyncIterator
-from typing import Annotated, AsyncIterator
 from uuid import UUID
 
-from fastapi import Depends, FastAPI, HTTPException, Response, status
+from fastapi import Depends, FastAPI, HTTPException, Request, Response, status
 
 from app.checker import EndpointChecker
-from app.config import get_settings
+from app.config import Settings, get_settings
 from app.logging import configure_logging
-from app.models import CurrentStatus, Monitor, MonitorCreate, MonitorUpdate, State
+from app.models import CheckResponse, CurrentStatus, Monitor, MonitorCreate, MonitorUpdate
-from app.security import DestinationRejected
 from app.store import MonitorStore
 
 
-@asynccontextmanager
+def not_found() -> HTTPException:
-async def lifespan(app: FastAPI) -> AsyncIterator[None]:
+    return HTTPException(status_code=404, detail={"code": "monitor_not_found", "message": "monitor does not exist"})
-    settings = get_settings()
-    configure_logging(settings.log_level)
-    app.state.store = MonitorStore()
-    app.state.checker = EndpointChecker(settings)
-    app.state.ready = True
-    yield
-    app.state.ready = False
 
 
-app = FastAPI(title="Endpoint Monitor", version="0.1.0", lifespan=lifespan)
+def get_store(request: Request) -> MonitorStore:
+    return request.app.state.store
 
 
-def store() -> MonitorStore:
+def get_checker(request: Request) -> EndpointChecker:
-    return app.state.store  # type: ignore[no-any-return]
+    return request.app.state.checker
 
 
-def checker() -> EndpointChecker:
+def create_app(
-    return app.state.checker  # type: ignore[no-any-return]
+    settings: Settings | None = None,
+    store: MonitorStore | None = None,
+    checker: EndpointChecker | None = None,
+) -> FastAPI:
+    config = settings or get_settings()
+
+    @asynccontextmanager
+    async def lifespan(app: FastAPI) -> AsyncIterator[None]:
+        configure_logging(config.log_level)
+        yield
+
+    app = FastAPI(title="Endpoint Monitor Service", version="0.1.0", lifespan=lifespan)
+    app.state.store = store or MonitorStore()
+    app.state.checker = checker or EndpointChecker(config)
+
+    @app.get("/health")
+    async def health() -> dict[str, str]:
+        return {"status": "ok"}
+
+    @app.get("/ready")
+    async def ready() -> dict[str, str]:
+        return {"status": "ready", "storage": "process-local-memory"}
+
+    @app.post("/monitors", response_model=Monitor, status_code=status.HTTP_201_CREATED)
+    async def create_monitor(value: MonitorCreate, state: MonitorStore = Depends(get_store)) -> Monitor:
+        return await state.create(value)
+
+    @app.get("/monitors", response_model=list[Monitor])
+    async def list_monitors(state: MonitorStore = Depends(get_store)) -> list[Monitor]:
+        return await state.list()
+
+    @app.get("/monitors/{monitor_id}", response_model=Monitor)
+    async def read_monitor(monitor_id: UUID, state: MonitorStore = Depends(get_store)) -> Monitor:
+        item = await state.get(monitor_id)
+        if item is None:
+            raise not_found()
+        return item
+
+    @app.put("/monitors/{monitor_id}", response_model=Monitor)
+    async def update_monitor(monitor_id: UUID, value: MonitorUpdate, state: MonitorStore = Depends(get_store)) -> Monitor:
+        item = await state.update(monitor_id, value)
+        if item is None:
+            raise not_found()
+        return item
+
+    @app.delete("/monitors/{monitor_id}", status_code=status.HTTP_204_NO_CONTENT)
+    async def delete_monitor(monitor_id: UUID, state: MonitorStore = Depends(get_store)) -> Response:
+        if not await state.delete(monitor_id):
+            raise not_found()
+        return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+    @app.post("/monitors/{monitor_id}/check", response_model=CheckResponse)
+    async def run_check(
+        monitor_id: UUID,
+        state: MonitorStore = Depends(get_store),
+        endpoint_checker: EndpointChecker = Depends(get_checker),
+    ) -> CheckResponse:
+        snapshot = await state.get(monitor_id)
+        if snapshot is None:
+            raise not_found()
+        result = await endpoint_checker.check(str(snapshot.url), str(monitor_id))
+        applied = await state.set_status_if_current(monitor_id, snapshot.revision, result)
+        return CheckResponse(monitor_id=monitor_id, status=result, applied=applied)
+
+    @app.get("/monitors/{monitor_id}/status", response_model=CurrentStatus | None)
+    async def current_status(monitor_id: UUID, state: MonitorStore = Depends(get_store)) -> CurrentStatus | None:
+        item = await state.get(monitor_id)
+        if item is None:
+            raise not_found()
+        return item.current_status
+
+    return app
 
 
-Store = Annotated[MonitorStore, Depends(store)]
+app = create_app()
-Checker = Annotated[EndpointChecker, Depends(checker)]
-
-
-def missing() -> HTTPException:
-    return HTTPException(status_code=404, detail="monitor not found")
-
-
-@app.get("/healthz")
-async def health() -> dict[str, str]:
-    return {"status": "ok"}
-
-
-@app.get("/readyz")
-async def readiness() -> dict[str, str]:
-    if not getattr(app.state, "ready", False):
-        raise HTTPException(status_code=503, detail="not ready")
-    return {"status": "ready"}
-
-
-@app.post("/v1/monitors", response_model=Monitor, status_code=status.HTTP_201_CREATED)
-async def create_monitor(payload: MonitorCreate, state: Store) -> Monitor:
-    return await state.create(payload)
-
-
-@app.get("/v1/monitors", response_model=list[Monitor])
-async def list_monitors(state: Store) -> list[Monitor]:
-    return await state.list()
-
-
-@app.get("/v1/monitors/{monitor_id}", response_model=Monitor)
-async def get_monitor(monitor_id: UUID, state: Store) -> Monitor:
-    item = await state.get(monitor_id)
-    if item is None:
-        raise missing()
-    return item
-
-
-@app.patch("/v1/monitors/{monitor_id}", response_model=Monitor)
-async def update_monitor(monitor_id: UUID, payload: MonitorUpdate, state: Store) -> Monitor:
-    if not payload.model_fields_set:
-        raise HTTPException(status_code=422, detail="at least one field is required")
-    item = await state.update(monitor_id, payload)
-    if item is None:
-        raise missing()
-    return item
-
-
-@app.delete("/v1/monitors/{monitor_id}", status_code=status.HTTP_204_NO_CONTENT)
-async def delete_monitor(monitor_id: UUID, state: Store) -> Response:
-    if not await state.delete(monitor_id):
-        raise missing()
-    return Response(status_code=status.HTTP_204_NO_CONTENT)
-
-
-@app.get("/v1/monitors/{monitor_id}/status", response_model=CurrentStatus)
-async def current_status(monitor_id: UUID, state: Store) -> CurrentStatus:
-    item = await state.get(monitor_id)
-    if item is None:
-        raise missing()
-    return item.current_status
-
-
-@app.post("/v1/monitors/{monitor_id}/check", response_model=CurrentStatus)
-async def check_monitor(monitor_id: UUID, state: Store, worker: Checker) -> CurrentStatus:
-    item = await state.get(monitor_id)
-    if item is None:
-        raise missing()
-    try:
-        result = await worker.check(str(monitor_id), str(item.url))
-    except DestinationRejected as exc:
-        result = CurrentStatus(
-            state=State.ERROR, checked_at=datetime.now(UTC), error=str(exc)[:200]
-        )
-        if await state.set_status(monitor_id, result) is None:
-            raise missing() from exc
-        raise HTTPException(status_code=400, detail=str(exc)) from exc
-    if await state.set_status(monitor_id, result) is None:
-        raise missing()
-    return result