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@@ -0,0 +1,258 @@
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+# -*- coding: utf-8 -*-
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+# Copyright 2015-2019 Prometheus Python Client Developers
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+# Copyright 2019 Matrix.org Foundation C.I.C.
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+#
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+# Licensed under the Apache License, Version 2.0 (the "License");
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+# you may not use this file except in compliance with the License.
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+# You may obtain a copy of the License at
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+#
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+# http://www.apache.org/licenses/LICENSE-2.0
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+#
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+# Unless required by applicable law or agreed to in writing, software
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+# distributed under the License is distributed on an "AS IS" BASIS,
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+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+# See the License for the specific language governing permissions and
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+# limitations under the License.
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+
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+"""
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+This code is based off `prometheus_client/exposition.py` from version 0.7.1.
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+
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+Due to the renaming of metrics in prometheus_client 0.4.0, this customised
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+vendoring of the code will emit both the old versions that Synapse dashboards
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+expect, and the newer "best practice" version of the up-to-date official client.
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+"""
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+
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+import math
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+import threading
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+from collections import namedtuple
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+from http.server import BaseHTTPRequestHandler, HTTPServer
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+from socketserver import ThreadingMixIn
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+from urllib.parse import parse_qs, urlparse
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+
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+from prometheus_client import REGISTRY
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+
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+from twisted.web.resource import Resource
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+
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+try:
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+ from prometheus_client.samples import Sample
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+except ImportError:
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+ Sample = namedtuple("Sample", ["name", "labels", "value", "timestamp", "exemplar"])
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+
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+
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+CONTENT_TYPE_LATEST = str("text/plain; version=0.0.4; charset=utf-8")
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+
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+
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+INF = float("inf")
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+MINUS_INF = float("-inf")
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+
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+
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+def floatToGoString(d):
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+ d = float(d)
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+ if d == INF:
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+ return "+Inf"
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+ elif d == MINUS_INF:
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+ return "-Inf"
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+ elif math.isnan(d):
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+ return "NaN"
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+ else:
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+ s = repr(d)
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+ dot = s.find(".")
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+ # Go switches to exponents sooner than Python.
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+ # We only need to care about positive values for le/quantile.
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+ if d > 0 and dot > 6:
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+ mantissa = "{0}.{1}{2}".format(s[0], s[1:dot], s[dot + 1 :]).rstrip("0.")
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+ return "{0}e+0{1}".format(mantissa, dot - 1)
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+ return s
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+
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+
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+def sample_line(line, name):
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+ if line.labels:
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+ labelstr = "{{{0}}}".format(
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+ ",".join(
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+ [
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+ '{0}="{1}"'.format(
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+ k,
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+ v.replace("\\", r"\\").replace("\n", r"\n").replace('"', r"\""),
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+ )
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+ for k, v in sorted(line.labels.items())
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+ ]
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+ )
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+ )
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+ else:
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+ labelstr = ""
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+ timestamp = ""
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+ if line.timestamp is not None:
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+ # Convert to milliseconds.
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+ timestamp = " {0:d}".format(int(float(line.timestamp) * 1000))
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+ return "{0}{1} {2}{3}\n".format(
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+ name, labelstr, floatToGoString(line.value), timestamp
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+ )
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+
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+
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+def nameify_sample(sample):
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+ """
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+ If we get a prometheus_client<0.4.0 sample as a tuple, transform it into a
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+ namedtuple which has the names we expect.
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+ """
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+ if not isinstance(sample, Sample):
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+ sample = Sample(*sample, None, None)
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+
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+ return sample
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+
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+
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+def generate_latest(registry, emit_help=False):
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+ output = []
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+
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+ for metric in registry.collect():
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+
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+ if metric.name.startswith("__unused"):
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+ continue
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+
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+ if not metric.samples:
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+ # No samples, don't bother.
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+ continue
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+
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+ mname = metric.name
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+ mnewname = metric.name
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+ mtype = metric.type
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+
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+ # OpenMetrics -> Prometheus
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+ if mtype == "counter":
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+ mnewname = mnewname + "_total"
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+ elif mtype == "info":
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+ mtype = "gauge"
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+ mnewname = mnewname + "_info"
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+ elif mtype == "stateset":
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+ mtype = "gauge"
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+ elif mtype == "gaugehistogram":
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+ mtype = "histogram"
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+ elif mtype == "unknown":
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+ mtype = "untyped"
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+
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+ # Output in the old format for compatibility.
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+ if emit_help:
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+ output.append(
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+ "# HELP {0} {1}\n".format(
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+ mname,
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+ metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
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+ )
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+ )
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+ output.append("# TYPE {0} {1}\n".format(mname, mtype))
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+ for sample in map(nameify_sample, metric.samples):
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+ # Get rid of the OpenMetrics specific samples
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+ for suffix in ["_created", "_gsum", "_gcount"]:
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+ if sample.name.endswith(suffix):
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+ break
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+ else:
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+ newname = sample.name.replace(mnewname, mname)
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+ if ":" in newname and newname.endswith("_total"):
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+ newname = newname[: -len("_total")]
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+ output.append(sample_line(sample, newname))
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+
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+ # Get rid of the weird colon things while we're at it
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+ if mtype == "counter":
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+ mnewname = mnewname.replace(":total", "")
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+ mnewname = mnewname.replace(":", "_")
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+
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+ if mname == mnewname:
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+ continue
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+
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+ # Also output in the new format, if it's different.
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+ if emit_help:
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+ output.append(
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+ "# HELP {0} {1}\n".format(
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+ mnewname,
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+ metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
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+ )
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+ )
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+ output.append("# TYPE {0} {1}\n".format(mnewname, mtype))
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+ for sample in map(nameify_sample, metric.samples):
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+ # Get rid of the OpenMetrics specific samples
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+ for suffix in ["_created", "_gsum", "_gcount"]:
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+ if sample.name.endswith(suffix):
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+ break
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+ else:
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+ output.append(
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+ sample_line(
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+ sample, sample.name.replace(":total", "").replace(":", "_")
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+ )
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+ )
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+
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+ return "".join(output).encode("utf-8")
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+
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+
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+class MetricsHandler(BaseHTTPRequestHandler):
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+ """HTTP handler that gives metrics from ``REGISTRY``."""
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+
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+ registry = REGISTRY
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+
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+ def do_GET(self):
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+ registry = self.registry
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+ params = parse_qs(urlparse(self.path).query)
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+
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+ if "help" in params:
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+ emit_help = True
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+ else:
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+ emit_help = False
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+
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+ try:
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+ output = generate_latest(registry, emit_help=emit_help)
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+ except Exception:
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+ self.send_error(500, "error generating metric output")
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+ raise
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+ self.send_response(200)
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+ self.send_header("Content-Type", CONTENT_TYPE_LATEST)
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+ self.end_headers()
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+ self.wfile.write(output)
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+
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+ def log_message(self, format, *args):
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+ """Log nothing."""
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+
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+ @classmethod
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+ def factory(cls, registry):
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+ """Returns a dynamic MetricsHandler class tied
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+ to the passed registry.
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+ """
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+ # This implementation relies on MetricsHandler.registry
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+ # (defined above and defaulted to REGISTRY).
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+
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+ # As we have unicode_literals, we need to create a str()
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+ # object for type().
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+ cls_name = str(cls.__name__)
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+ MyMetricsHandler = type(cls_name, (cls, object), {"registry": registry})
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+ return MyMetricsHandler
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+
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+
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+class _ThreadingSimpleServer(ThreadingMixIn, HTTPServer):
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+ """Thread per request HTTP server."""
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+
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+ # Make worker threads "fire and forget". Beginning with Python 3.7 this
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+ # prevents a memory leak because ``ThreadingMixIn`` starts to gather all
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+ # non-daemon threads in a list in order to join on them at server close.
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+ # Enabling daemon threads virtually makes ``_ThreadingSimpleServer`` the
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+ # same as Python 3.7's ``ThreadingHTTPServer``.
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+ daemon_threads = True
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+
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+
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+def start_http_server(port, addr="", registry=REGISTRY):
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+ """Starts an HTTP server for prometheus metrics as a daemon thread"""
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+ CustomMetricsHandler = MetricsHandler.factory(registry)
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+ httpd = _ThreadingSimpleServer((addr, port), CustomMetricsHandler)
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+ t = threading.Thread(target=httpd.serve_forever)
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+ t.daemon = True
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+ t.start()
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+
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+
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+class MetricsResource(Resource):
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+ """
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+ Twisted ``Resource`` that serves prometheus metrics.
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+ """
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+
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+ isLeaf = True
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+
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+ def __init__(self, registry=REGISTRY):
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+ self.registry = registry
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+
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+ def render_GET(self, request):
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+ request.setHeader(b"Content-Type", CONTENT_TYPE_LATEST.encode("ascii"))
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+ return generate_latest(self.registry)
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Amber Brown