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- # Copyright 2015-2019 Prometheus Python Client Developers
- # Copyright 2019 Matrix.org Foundation C.I.C.
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # http://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # See the License for the specific language governing permissions and
- # limitations under the License.
- """
- This code is based off `prometheus_client/exposition.py` from version 0.7.1.
- Due to the renaming of metrics in prometheus_client 0.4.0, this customised
- vendoring of the code will emit both the old versions that Synapse dashboards
- expect, and the newer "best practice" version of the up-to-date official client.
- """
- import logging
- import math
- import threading
- from http.server import BaseHTTPRequestHandler, HTTPServer
- from socketserver import ThreadingMixIn
- from typing import Any, Dict, List, Type, Union
- from urllib.parse import parse_qs, urlparse
- from prometheus_client import REGISTRY, CollectorRegistry
- from prometheus_client.core import Sample
- from twisted.web.resource import Resource
- from twisted.web.server import Request
- logger = logging.getLogger(__name__)
- CONTENT_TYPE_LATEST = "text/plain; version=0.0.4; charset=utf-8"
- def floatToGoString(d: Union[int, float]) -> str:
- d = float(d)
- if d == math.inf:
- return "+Inf"
- elif d == -math.inf:
- return "-Inf"
- elif math.isnan(d):
- return "NaN"
- else:
- s = repr(d)
- dot = s.find(".")
- # Go switches to exponents sooner than Python.
- # We only need to care about positive values for le/quantile.
- if d > 0 and dot > 6:
- mantissa = f"{s[0]}.{s[1:dot]}{s[dot + 1 :]}".rstrip("0.")
- return f"{mantissa}e+0{dot - 1}"
- return s
- def sample_line(line: Sample, name: str) -> str:
- if line.labels:
- labelstr = "{{{0}}}".format(
- ",".join(
- [
- '{}="{}"'.format(
- k,
- v.replace("\\", r"\\").replace("\n", r"\n").replace('"', r"\""),
- )
- for k, v in sorted(line.labels.items())
- ]
- )
- )
- else:
- labelstr = ""
- timestamp = ""
- if line.timestamp is not None:
- # Convert to milliseconds.
- timestamp = f" {int(float(line.timestamp) * 1000):d}"
- return "{}{} {}{}\n".format(name, labelstr, floatToGoString(line.value), timestamp)
- # Mapping from new metric names to legacy metric names.
- # We translate these back to their old names when exposing them through our
- # legacy vendored exporter.
- # Only this legacy exposition module applies these name changes.
- LEGACY_METRIC_NAMES = {
- "synapse_util_caches_cache_hits": "synapse_util_caches_cache:hits",
- "synapse_util_caches_cache_size": "synapse_util_caches_cache:size",
- "synapse_util_caches_cache_evicted_size": "synapse_util_caches_cache:evicted_size",
- "synapse_util_caches_cache": "synapse_util_caches_cache:total",
- "synapse_util_caches_response_cache_size": "synapse_util_caches_response_cache:size",
- "synapse_util_caches_response_cache_hits": "synapse_util_caches_response_cache:hits",
- "synapse_util_caches_response_cache_evicted_size": "synapse_util_caches_response_cache:evicted_size",
- "synapse_util_caches_response_cache": "synapse_util_caches_response_cache:total",
- "synapse_federation_client_sent_pdu_destinations": "synapse_federation_client_sent_pdu_destinations:total",
- "synapse_federation_client_sent_pdu_destinations_count": "synapse_federation_client_sent_pdu_destinations:count",
- "synapse_admin_mau_current": "synapse_admin_mau:current",
- "synapse_admin_mau_max": "synapse_admin_mau:max",
- "synapse_admin_mau_registered_reserved_users": "synapse_admin_mau:registered_reserved_users",
- }
- def generate_latest(registry: CollectorRegistry, emit_help: bool = False) -> bytes:
- """
- Generate metrics in legacy format. Modern metrics are generated directly
- by prometheus-client.
- """
- output = []
- for metric in registry.collect():
- if not metric.samples:
- # No samples, don't bother.
- continue
- # Translate to legacy metric name if it has one.
- mname = LEGACY_METRIC_NAMES.get(metric.name, metric.name)
- mnewname = metric.name
- mtype = metric.type
- # OpenMetrics -> Prometheus
- if mtype == "counter":
- mnewname = mnewname + "_total"
- elif mtype == "info":
- mtype = "gauge"
- mnewname = mnewname + "_info"
- elif mtype == "stateset":
- mtype = "gauge"
- elif mtype == "gaugehistogram":
- mtype = "histogram"
- elif mtype == "unknown":
- mtype = "untyped"
- # Output in the old format for compatibility.
- if emit_help:
- output.append(
- "# HELP {} {}\n".format(
- mname,
- metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
- )
- )
- output.append(f"# TYPE {mname} {mtype}\n")
- om_samples: Dict[str, List[str]] = {}
- for s in metric.samples:
- for suffix in ["_created", "_gsum", "_gcount"]:
- if s.name == mname + suffix:
- # OpenMetrics specific sample, put in a gauge at the end.
- # (these come from gaugehistograms which don't get renamed,
- # so no need to faff with mnewname)
- om_samples.setdefault(suffix, []).append(sample_line(s, s.name))
- break
- else:
- newname = s.name.replace(mnewname, mname)
- if ":" in newname and newname.endswith("_total"):
- newname = newname[: -len("_total")]
- output.append(sample_line(s, newname))
- for suffix, lines in sorted(om_samples.items()):
- if emit_help:
- output.append(
- "# HELP {}{} {}\n".format(
- mname,
- suffix,
- metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
- )
- )
- output.append(f"# TYPE {mname}{suffix} gauge\n")
- output.extend(lines)
- # Get rid of the weird colon things while we're at it
- if mtype == "counter":
- mnewname = mnewname.replace(":total", "")
- mnewname = mnewname.replace(":", "_")
- if mname == mnewname:
- continue
- # Also output in the new format, if it's different.
- if emit_help:
- output.append(
- "# HELP {} {}\n".format(
- mnewname,
- metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
- )
- )
- output.append(f"# TYPE {mnewname} {mtype}\n")
- for s in metric.samples:
- # Get rid of the OpenMetrics specific samples (we should already have
- # dealt with them above anyway.)
- for suffix in ["_created", "_gsum", "_gcount"]:
- if s.name == mname + suffix:
- break
- else:
- sample_name = LEGACY_METRIC_NAMES.get(s.name, s.name)
- output.append(
- sample_line(s, sample_name.replace(":total", "").replace(":", "_"))
- )
- return "".join(output).encode("utf-8")
- class MetricsHandler(BaseHTTPRequestHandler):
- """HTTP handler that gives metrics from ``REGISTRY``."""
- registry = REGISTRY
- def do_GET(self) -> None:
- registry = self.registry
- params = parse_qs(urlparse(self.path).query)
- if "help" in params:
- emit_help = True
- else:
- emit_help = False
- try:
- output = generate_latest(registry, emit_help=emit_help)
- except Exception:
- self.send_error(500, "error generating metric output")
- raise
- try:
- self.send_response(200)
- self.send_header("Content-Type", CONTENT_TYPE_LATEST)
- self.send_header("Content-Length", str(len(output)))
- self.end_headers()
- self.wfile.write(output)
- except BrokenPipeError as e:
- logger.warning(
- "BrokenPipeError when serving metrics (%s). Did Prometheus restart?", e
- )
- def log_message(self, format: str, *args: Any) -> None:
- """Log nothing."""
- @classmethod
- def factory(cls, registry: CollectorRegistry) -> Type:
- """Returns a dynamic MetricsHandler class tied
- to the passed registry.
- """
- # This implementation relies on MetricsHandler.registry
- # (defined above and defaulted to REGISTRY).
- # As we have unicode_literals, we need to create a str()
- # object for type().
- cls_name = str(cls.__name__)
- MyMetricsHandler = type(cls_name, (cls, object), {"registry": registry})
- return MyMetricsHandler
- class _ThreadingSimpleServer(ThreadingMixIn, HTTPServer):
- """Thread per request HTTP server."""
- # Make worker threads "fire and forget". Beginning with Python 3.7 this
- # prevents a memory leak because ``ThreadingMixIn`` starts to gather all
- # non-daemon threads in a list in order to join on them at server close.
- # Enabling daemon threads virtually makes ``_ThreadingSimpleServer`` the
- # same as Python 3.7's ``ThreadingHTTPServer``.
- daemon_threads = True
- def start_http_server(
- port: int, addr: str = "", registry: CollectorRegistry = REGISTRY
- ) -> None:
- """Starts an HTTP server for prometheus metrics as a daemon thread"""
- CustomMetricsHandler = MetricsHandler.factory(registry)
- httpd = _ThreadingSimpleServer((addr, port), CustomMetricsHandler)
- t = threading.Thread(target=httpd.serve_forever)
- t.daemon = True
- t.start()
- class MetricsResource(Resource):
- """
- Twisted ``Resource`` that serves prometheus metrics.
- """
- isLeaf = True
- def __init__(self, registry: CollectorRegistry = REGISTRY):
- self.registry = registry
- def render_GET(self, request: Request) -> bytes:
- request.setHeader(b"Content-Type", CONTENT_TYPE_LATEST.encode("ascii"))
- response = generate_latest(self.registry)
- request.setHeader(b"Content-Length", str(len(response)))
- return response
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