83 lines
2.5 KiB
TypeScript
83 lines
2.5 KiB
TypeScript
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import type { Context } from 'hono'
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import type { CounterConfiguration, HistogramConfiguration, Metric } from 'prom-client'
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import { Counter, Histogram, type Registry } from 'prom-client'
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export type MetricOptions = {
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disabled?: boolean;
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customLabels?: Record<string, (c: Context) => string>;
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} & (
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({ type: 'counter' } & CounterConfiguration<string>) |
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({ type: 'histogram' } & HistogramConfiguration<string>)
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)
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const standardMetrics = {
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requestDuration: {
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type: 'histogram',
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name: 'http_request_duration_seconds',
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help: 'Duration of HTTP requests in seconds',
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labelNames: ['method', 'status', 'ok', 'route'],
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// OpenTelemetry recommendation for histogram buckets of http request duration:
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// https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#metric-httpserverrequestduration
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buckets: [ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ],
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},
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requestsTotal: {
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type: 'counter',
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name: 'http_requests_total',
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help: 'Total number of HTTP requests',
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labelNames: ['method', 'status', 'ok', 'route'],
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},
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} satisfies Record<string, MetricOptions>
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export type MetricName = keyof typeof standardMetrics
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export type CustomMetricsOptions = {
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[Name in MetricName]?: Partial<Omit<MetricOptions, 'type' | 'collect' | 'labelNames'>>
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}
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type CreatedMetrics = {
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[Name in MetricName]: (typeof standardMetrics)[Name]['type'] extends 'counter' ? Counter<string> : Histogram<string>
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}
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const getMetricConstructor = (type: MetricOptions['type']) => ({
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counter: Counter,
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histogram: Histogram,
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})[type]
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export const createStandardMetrics = ({
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registry,
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prefix = '',
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customOptions,
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} : {
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registry: Registry;
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prefix?: string;
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customOptions?: CustomMetricsOptions;
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}) => {
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const createdMetrics: Record<string, Metric> = {}
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for (const [metric, options] of Object.entries(standardMetrics)) {
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const opts: MetricOptions = {
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...options,
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...customOptions?.[metric as MetricName],
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}
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if (opts.disabled) {
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continue
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}
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const MetricConstructor = getMetricConstructor(opts.type)
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createdMetrics[metric] = new MetricConstructor({
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...(opts as object),
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name: `${prefix}${opts.name}`,
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help: opts.help,
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registers: [...opts.registers ?? [], registry],
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labelNames: [...opts.labelNames ?? [], ...Object.keys(opts.customLabels ?? {})],
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...(opts.type === 'histogram' && opts.buckets && {
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buckets: opts.buckets,
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}),
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})
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}
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return createdMetrics as CreatedMetrics
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}
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