@graphql-yoga/plugin-prometheus/esm/index.js

Prometheus plugin for GraphQL Yoga.

import { usePrometheus as useEnvelopPrometheus, } from '@envelop/prometheus';
import { Histogram, register as defaultRegistry } from 'prom-client';
function headersToObj(headers) {
    const obj = {};
    headers.forEach((value, key) => {
        obj[key] = value;
    });
    return obj;
}
export function usePrometheus(options) {
    const endpoint = options.endpoint || '/metrics';
    const registry = options.registry || defaultRegistry;
    const httpHistogram = new Histogram({
        name: 'graphql_yoga_http_duration',
        help: 'Time spent on HTTP connection',
        labelNames: [
            'url',
            'method',
            'requestHeaders',
            'statusCode',
            'statusText',
            'responseHeaders',
        ],
        registers: [registry],
    });
    const startByRequest = new WeakMap();
    return {
        onPluginInit({ addPlugin }) {
            addPlugin(useEnvelopPrometheus({ ...options, registry }));
        },
        async onRequest({ request, url, fetchAPI, endResponse }) {
            startByRequest.set(request, Date.now());
            if (url.pathname === endpoint) {
                const metrics = await registry.metrics();
                const response = new fetchAPI.Response(metrics, {
                    headers: {
                        'Content-Type': registry.contentType,
                    },
                });
                endResponse(response);
            }
        },
        onResponse({ request, response }) {
            const start = startByRequest.get(request);
            if (start) {
                const duration = Date.now() - start;
                httpHistogram.observe({
                    url: request.url,
                    method: request.method,
                    requestHeaders: JSON.stringify(headersToObj(request.headers)),
                    statusCode: response.status,
                    statusText: response.statusText,
                    responseHeaders: JSON.stringify(headersToObj(response.headers)),
                }, duration);
            }
        },
    };
}