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9e93b10 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 | """OpenTelemetry metrics bootstrap for rexpro-ai.
This module initialises a MeterProvider that sends metrics to an OTLP
collector. The collector is responsible for exposing a Prometheus
`/metrics` endpoint – rexpro does **not** expose it directly.
Metrics collected:
* http.server.requests (counter)
* http.server.duration (histogram, milliseconds)
Attributes used: http.method, http.route, http.status_code
If you wish to add more attributes (e.g. user-agent) you can, but beware of
high-cardinality label sets.
"""
from __future__ import annotations
import datetime
import logging
import time
from base64 import b64encode
from typing import Dict, Iterable, List, Optional
from fastapi import FastAPI, Request
from rexpro_ai.env import (
OTEL_METRICS_BASIC_AUTH_PASSWORD,
OTEL_METRICS_BASIC_AUTH_USERNAME,
OTEL_METRICS_EXPORT_INTERVAL_MILLIS,
OTEL_METRICS_EXPORTER_OTLP_ENDPOINT,
OTEL_METRICS_EXPORTER_OTLP_INSECURE,
OTEL_METRICS_OTLP_SPAN_EXPORTER,
OTEL_SERVICE_NAME,
)
from rexpro_ai.models.users import User
from opentelemetry import metrics
from opentelemetry.exporter.otlp.proto.grpc.metric_exporter import (
OTLPMetricExporter,
)
from opentelemetry.exporter.otlp.proto.http.metric_exporter import (
OTLPMetricExporter as OTLPHttpMetricExporter,
)
from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.metrics.export import (
PeriodicExportingMetricReader,
)
from opentelemetry.sdk.metrics.view import View
from opentelemetry.sdk.resources import Resource
from sqlalchemy import Engine, func, select
from sqlalchemy.orm import Session
logger = logging.getLogger(__name__)
# ---------------------------------------------------------------------------
# Sync DB helpers for OTel gauge callbacks
#
# The OTel Python SDK calls observable-instrument callbacks *synchronously*
# from a background collection thread — async callbacks are NOT supported
# (the SDK does not ``await`` the return value).
#
# Rather than bridging into the async event loop, we run plain synchronous
# SQL queries using the sync engine that is already available at setup time.
# This avoids any cross-thread / cross-loop concerns entirely.
# ---------------------------------------------------------------------------
def _count_total_users(db_engine: Engine) -> Optional[int]:
"""Return the total number of registered users (sync)."""
with Session(db_engine) as session:
return session.execute(select(func.count()).select_from(User)).scalar()
def _count_active_users(db_engine: Engine) -> Optional[int]:
"""Return the number of users active within the last 3 minutes (sync)."""
three_minutes_ago = int(time.time()) - 180
with Session(db_engine) as session:
return session.execute(
select(func.count()).select_from(User).filter(User.last_active_at >= three_minutes_ago)
).scalar()
def _count_users_active_today(db_engine: Engine) -> Optional[int]:
"""Return the number of users active since midnight today (sync)."""
now = int(datetime.datetime.now().timestamp())
today_midnight = now - (now % 86400)
with Session(db_engine) as session:
return session.execute(
select(func.count()).select_from(User).filter(User.last_active_at > today_midnight)
).scalar()
def _build_meter_provider(resource: Resource) -> MeterProvider:
"""Return a configured MeterProvider."""
headers = []
if OTEL_METRICS_BASIC_AUTH_USERNAME and OTEL_METRICS_BASIC_AUTH_PASSWORD:
auth_string = f'{OTEL_METRICS_BASIC_AUTH_USERNAME}:{OTEL_METRICS_BASIC_AUTH_PASSWORD}'
auth_header = b64encode(auth_string.encode()).decode()
headers = [('authorization', f'Basic {auth_header}')]
# Periodic reader pushes metrics over OTLP/gRPC to collector
if OTEL_METRICS_OTLP_SPAN_EXPORTER == 'http':
readers: List[PeriodicExportingMetricReader] = [
PeriodicExportingMetricReader(
OTLPHttpMetricExporter(endpoint=OTEL_METRICS_EXPORTER_OTLP_ENDPOINT, headers=headers),
export_interval_millis=OTEL_METRICS_EXPORT_INTERVAL_MILLIS,
)
]
else:
readers: List[PeriodicExportingMetricReader] = [
PeriodicExportingMetricReader(
OTLPMetricExporter(
endpoint=OTEL_METRICS_EXPORTER_OTLP_ENDPOINT,
insecure=OTEL_METRICS_EXPORTER_OTLP_INSECURE,
headers=headers,
),
export_interval_millis=OTEL_METRICS_EXPORT_INTERVAL_MILLIS,
)
]
# Optional view to limit cardinality: drop user-agent etc.
views: List[View] = [
View(
instrument_name='http.server.duration',
attribute_keys=['http.method', 'http.route', 'http.status_code'],
),
View(
instrument_name='http.server.requests',
attribute_keys=['http.method', 'http.route', 'http.status_code'],
),
View(
instrument_name='rexpro.users.total',
),
View(
instrument_name='rexpro.users.active',
),
View(
instrument_name='rexpro.users.active.today',
),
]
provider = MeterProvider(
resource=resource,
metric_readers=list(readers),
views=views,
)
return provider
def setup_metrics(app: FastAPI, resource: Resource, db_engine: Engine) -> None:
"""Attach OTel metrics middleware to *app* and initialise provider."""
metrics.set_meter_provider(_build_meter_provider(resource))
meter = metrics.get_meter(__name__)
# Instruments
request_counter = meter.create_counter(
name='http.server.requests',
description='Counts the total number of inbound HTTP requests.',
unit='1',
)
duration_histogram = meter.create_histogram(
name='http.server.duration',
description='Measures the duration of inbound HTTP requests.',
unit='ms',
)
# -- Observable gauge callbacks ----------------------------------------
# These are called synchronously by the OTel SDK from a background
# collection thread. They use the sync DB engine directly — no async
# bridging required.
def observe_total_users(
options: metrics.CallbackOptions,
) -> Iterable[metrics.Observation]:
try:
value = _count_total_users(db_engine)
if value is not None:
yield metrics.Observation(value=value)
except Exception:
logger.debug('Failed to observe total users', exc_info=True)
def observe_active_users(
options: metrics.CallbackOptions,
) -> Iterable[metrics.Observation]:
try:
value = _count_active_users(db_engine)
if value is not None:
yield metrics.Observation(value=value)
except Exception:
logger.debug('Failed to observe active users', exc_info=True)
def observe_users_active_today(
options: metrics.CallbackOptions,
) -> Iterable[metrics.Observation]:
try:
value = _count_users_active_today(db_engine)
if value is not None:
yield metrics.Observation(value=value)
except Exception:
logger.debug('Failed to observe users active today', exc_info=True)
meter.create_observable_gauge(
name='rexpro.users.total',
description='Total number of registered users',
unit='users',
callbacks=[observe_total_users],
)
meter.create_observable_gauge(
name='rexpro.users.active',
description='Number of currently active users',
unit='users',
callbacks=[observe_active_users],
)
meter.create_observable_gauge(
name='rexpro.users.active.today',
description='Number of users active since midnight today',
unit='users',
callbacks=[observe_users_active_today],
)
# FastAPI middleware
@app.middleware('http')
async def _metrics_middleware(request: Request, call_next):
start_time = time.perf_counter()
status_code = None
try:
response = await call_next(request)
status_code = getattr(response, 'status_code', 500)
return response
except Exception:
status_code = 500
raise
finally:
elapsed_ms = (time.perf_counter() - start_time) * 1000.0
# Route template e.g. "/items/{item_id}" instead of real path.
route = request.scope.get('route')
route_path = getattr(route, 'path', request.url.path)
attrs: Dict[str, str | int] = {
'http.method': request.method,
'http.route': route_path,
'http.status_code': status_code,
}
request_counter.add(1, attrs)
duration_histogram.record(elapsed_ms, attrs)
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