Source code for molten.contrib.prometheus
# This file is a part of molten.
#
# Copyright (C) 2018 CLEARTYPE SRL <[email protected]>
#
# molten is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# molten is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import time
from io import BytesIO
from typing import Any, Callable
from molten import HTTP_200, Request, Response
try:
from prometheus_client import (
CONTENT_TYPE_LATEST, CollectorRegistry, Counter, Gauge, Histogram,
generate_latest, multiprocess
)
except ImportError: # pragma: no cover
raise ImportError("'prometheus_client' package missing. Run 'pip install prometheus-client'.")
REQUEST_DURATION = Histogram(
"http_request_duration_seconds",
"Time spent processing a request.",
["method", "path"],
)
REQUEST_COUNT = Counter(
"http_requests_total",
"Request count by method, path and status line.",
["method", "path", "status"],
)
REQUESTS_INPROGRESS = Gauge(
"http_requests_inprogress",
"Requests in progress by method and path",
["method", "path"],
)
#: Micro-optimization to avoid allocating a new dict on every metrics
#: request. Response itself copies the headers its given so this
#: shouldn't be a problem.
_HEADERS = {"content-type": CONTENT_TYPE_LATEST}
[docs]def expose_metrics() -> Response:
"""Expose prometheus metrics from the current process.
"""
return Response(HTTP_200, headers=_HEADERS, stream=BytesIO(generate_latest()))
[docs]def expose_metrics_multiprocess() -> Response: # pragma: no cover
"""Expose prometheus metrics from the current set of processes.
Use this instead of expose_metrics if you're using a multi-process
server.
"""
registry = CollectorRegistry()
multiprocess.MultiProcessCollector(registry)
return Response(HTTP_200, headers=_HEADERS, stream=BytesIO(generate_latest(registry)))
[docs]def prometheus_middleware(handler: Callable[..., Any]) -> Callable[..., Any]:
"""Collect prometheus metrics from your handlers.
"""
def middleware(request: Request) -> Any:
status = "500 Internal Server Error"
start_time = time.monotonic()
requests_inprogress = REQUESTS_INPROGRESS.labels(request.method, request.path)
requests_inprogress.inc()
try:
response = handler()
status = response.status
return response
finally:
requests_inprogress.dec()
REQUEST_COUNT.labels(request.method, request.path, status).inc()
REQUEST_DURATION.labels(request.method, request.path).observe(time.monotonic() - start_time)
return middleware