Logging, Monitoring ও Load Testing

uv add structlog

# core/logging.py
import logging
import structlog


def setup_logging(json_logs: bool) -> None:
    logging.basicConfig(level=logging.INFO, format="%(message)s")
    structlog.configure(
        processors=[
            structlog.contextvars.merge_contextvars,          # request_id ইত্যাদি নিজে যোগ হবে
            structlog.processors.add_log_level,
            structlog.processors.TimeStamper(fmt="iso", utc=True),
            structlog.processors.format_exc_info,
            structlog.processors.JSONRenderer() if json_logs else structlog.dev.ConsoleRenderer(),
        ],
    )


log = structlog.get_logger()

# middleware: প্রতিটা request এ id আর সময়
import time
import uuid
import structlog

@app.middleware("http")
async def request_context(request, call_next):
    rid = request.headers.get("X-Request-ID") or uuid.uuid4().hex[:16]
    structlog.contextvars.clear_contextvars()
    structlog.contextvars.bind_contextvars(request_id=rid, path=request.url.path, method=request.method)
    start = time.perf_counter()
    try:
        response = await call_next(request)
    except Exception:
        log.exception("request_failed")
        raise
    ms = round((time.perf_counter() - start) * 1000, 1)
    log.info("request_done", status=response.status_code, duration_ms=ms)
    response.headers["X-Request-ID"] = rid
    return response

log.info("order_created", order_id=order.id, total=order.total, restaurant_id=order.restaurant_id)

{"event": "order_created", "order_id": 1042, "total": 55000, "restaurant_id": 15,
 "request_id": "a8f3c19e0b2d4f11", "path": "/v1/orders", "level": "info", "timestamp": "2026-10-29T06:15:02Z"}

uv add "sentry-sdk[fastapi]"

import sentry_sdk

sentry_sdk.init(
    dsn=settings.sentry_dsn,
    environment=settings.environment,
    release=settings.git_sha,                 # কোন deploy এ bug এলো
    traces_sample_rate=0.1,                   # ১০% request এর performance trace
    send_default_pii=False,                   # ব্যক্তিগত তথ্য পাঠাবে না
)

uv add prometheus-fastapi-instrumentator

from prometheus_fastapi_instrumentator import Instrumentator

Instrumentator().instrument(app).expose(app, endpoint="/metrics", include_in_schema=False)

from prometheus_client import Counter, Histogram

ORDERS = Counter("orders_created_total", "মোট order", ["city"])
PAYMENT_LATENCY = Histogram("payment_gateway_seconds", "Payment gateway এর সময়")

ORDERS.labels(city="dhaka").inc()
with PAYMENT_LATENCY.time():
    await gateway.charge(...)

uv add --dev locust

# locustfile.py
import random
import uuid
from locust import HttpUser, task, between


class NoteUser(HttpUser):
    wait_time = between(1, 3)                       # প্রতিটা কাজের মাঝে ১-৩ সেকেন্ড

    def on_start(self):
        email = f"load-{uuid.uuid4().hex[:8]}@test.com"
        self.client.post("/v1/auth/register", json={"email": email, "name": "Load", "password": "secret123"})
        r = self.client.post("/v1/auth/login", json={"email": email, "password": "secret123"})
        self.client.headers["Authorization"] = f"Bearer {r.json()['access_token']}"

    @task(5)                                         # সবচেয়ে বেশি: list দেখা
    def list_notes(self):
        self.client.get("/v1/notes?limit=20", name="/v1/notes")

    @task(2)
    def create_note(self):
        self.client.post("/v1/notes", json={"title": f"নোট {random.randint(1, 9999)}"},
                         headers={"Idempotency-Key": uuid.uuid4().hex})

    @task(1)
    def search(self):
        self.client.get("/v1/notes?search=নোট", name="/v1/notes?search")

uv run locust -H http://localhost:8000
# browser এ http://localhost:8089, user সংখ্যা ধীরে ধীরে বাড়াও