overleaf/libraries/metrics/README.md

overleaf/metrics-module

Wrappers the prom-client npm module to provide Prometheus metrics at /metrics.

Use:

// Metrics must be initialized before importing anything else
require('@overleaf/metrics/initialize')

const express = require('express')
const metrics = require('@overleaf/metrics')
const app = express()
metrics.injectMetricsRoute(app)

Request logging can be enabled:

const logger = require('@overleaf/logger')
...
app.use(metrics.http.monitor(logger))

The metrics module can be configured through the following environment variables:

• DEBUG_METRICS - enables display of debugging messages to the console.
• GCP_OPENTELEMETRY - enables OpenTelemetry tracing for GCP
• JAEGER_OPENTELEMETRY - enables OpenTelemetry tracing for Jaeger (in the dev environment)
• METRICS_APP_NAME - the app label for metrics and spans
• METRICS_COMPRESSION_LEVEL - sets the compression level for /metrics
• STACKDRIVER_LOGGING - toggles the request logging format
• UV_THREADPOOL_SIZE - sets the libuv thread pool size