Aleksei Sokol
53f14a8624
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Changes: - put ObservabilityMiddleware before ExceptionHandlerMiddleware to avoid repetative code - add application startup and last metrics update metrics along with CPU usage metric and threads count - move host and port to new uvicorn section at config along with new reload and forwarded_allow_ips - add request_id and remove trace_id/span_id generation if tracing is disabled - move logging logic from utils to observability - pass trace_id/span_id in HEX form
109 lines
4.2 KiB
Django/Jinja
109 lines
4.2 KiB
Django/Jinja
"""Observability middleware is defined here."""
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import time
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import uuid
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from fastapi import FastAPI, Request
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from opentelemetry import context as tracing_context
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from opentelemetry import trace
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from opentelemetry.semconv.attributes import http_attributes, url_attributes
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from opentelemetry.trace import NonRecordingSpan, SpanContext, TraceFlags
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from starlette.middleware.base import BaseHTTPMiddleware
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from {{project_slug}}.dependencies import logger_dep
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from {{project_slug}}.observability.metrics import Metrics
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from {{project_slug}}.observability.utils import URLsMapper, get_tracing_headers
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_tracer = trace.get_tracer_provider().get_tracer(__name__)
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class ObservabilityMiddleware(BaseHTTPMiddleware): # pylint: disable=too-few-public-methods
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"""Middleware for global observability requests.
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- Generate tracing span and adds response headers
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'X-Trace-Id', 'X-Span-Id' (if tracing is configured) and 'X-Request-Id'
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- Binds trace_id it to logger passing it in request state (`request.state.logger`)
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- Collects metrics for Prometheus
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"""
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def __init__(self, app: FastAPI, metrics: Metrics, urls_mapper: URLsMapper):
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super().__init__(app)
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self._http_metrics = metrics.http
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self._urls_mapper = urls_mapper
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async def dispatch(self, request: Request, call_next):
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logger = logger_dep.from_request(request)
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_try_get_parent_span_id(request)
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with _tracer.start_as_current_span("http request") as span:
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request_id = str(uuid.uuid4())
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logger = logger.bind(request_id=request_id)
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logger_dep.attach_to_request(request, logger)
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span.set_attributes(
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{
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http_attributes.HTTP_REQUEST_METHOD: request.method,
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url_attributes.URL_PATH: request.url.path,
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url_attributes.URL_QUERY: str(request.query_params),
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"request_client": request.client.host,
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"request_id": request_id,
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}
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)
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await logger.ainfo(
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"http begin",
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client=request.client.host,
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path_params=request.path_params,
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method=request.method,
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url=str(request.url),
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)
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path_for_metric = self._urls_mapper.map(request.method, request.url.path)
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self._http_metrics.requests_started.add(1, {"method": request.method, "path": path_for_metric})
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self._http_metrics.inflight_requests.add(1)
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time_begin = time.monotonic()
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result = await call_next(request)
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duration_seconds = time.monotonic() - time_begin
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result.headers.update({"X-Request-Id": request_id} | get_tracing_headers())
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await logger.ainfo("http end", time_consumed=round(duration_seconds, 3), status_code=result.status_code)
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self._http_metrics.requests_finished.add(
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1,
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{
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http_attributes.HTTP_REQUEST_METHOD: request.method,
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url_attributes.URL_PATH: path_for_metric,
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http_attributes.HTTP_RESPONSE_STATUS_CODE: result.status_code,
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},
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)
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self._http_metrics.inflight_requests.add(-1)
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if result.status_code // 100 == 2:
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span.set_status(trace.StatusCode.OK)
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span.set_attribute(http_attributes.HTTP_RESPONSE_STATUS_CODE, result.status_code)
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self._http_metrics.request_processing_duration.record(
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duration_seconds, {"method": request.method, "path": path_for_metric}
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)
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return result
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def _try_get_parent_span_id(request: Request) -> None:
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trace_id_str = request.headers.get("X-Trace-Id")
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span_id_str = request.headers.get("X-Span-Id")
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if trace_id_str is None or span_id_str is None:
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return
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if not trace_id_str.isalnum() or not span_id_str.isalnum():
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return
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try:
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span_context = SpanContext(
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trace_id=int(trace_id_str, 16), span_id=int(span_id_str, 16), is_remote=True, trace_flags=TraceFlags(0x01)
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)
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except Exception: # pylint: disable=broad-except
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return
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ctx = trace.set_span_in_context(NonRecordingSpan(span_context))
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tracing_context.attach(ctx)
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