Add experimental configuration option to allow disabling legacy Prometheus metric names. (#13540)

Co-authored-by: David Robertson <davidr@element.io>

1 files changed, 0 insertions, 262 deletions

diff --git a/synapse/metrics/_exposition.py b/synapse/metrics/_exposition.py
deleted file mode 100644
index 353d0a63b6..0000000000
--- a/synapse/metrics/_exposition.py
+++ /dev/null
@@ -1,262 +0,0 @@
-# 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 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
-
-from synapse.util import caches
-
-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)
-
-
-def generate_latest(registry: CollectorRegistry, emit_help: bool = False) -> bytes:
-
-    # Trigger the cache metrics to be rescraped, which updates the common
-    # metrics but do not produce metrics themselves
-    for collector in caches.collectors_by_name.values():
-        collector.collect()
-
-    output = []
-
-    for metric in registry.collect():
-        if not metric.samples:
-            # No samples, don't bother.
-            continue
-
-        mname = 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 == metric.name + 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(
-                        metric.name,
-                        suffix,
-                        metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
-                    )
-                )
-            output.append(f"# TYPE {metric.name}{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 == metric.name + suffix:
-                    break
-            else:
-                output.append(
-                    sample_line(s, s.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
-        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)
-
-    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