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

Prometheus plugin for GraphQL Yoga.

import { usePrometheus as useEnvelopPrometheus, createCounter, createHistogram, createSummary, } from '@envelop/prometheus';
import { getOperationAST } from 'graphql';
import { Histogram, register as defaultRegistry } from 'prom-client';
export { createCounter, createHistogram, createSummary };
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;
    let httpHistogram;
    if (options.http) {
        const labelNames = [
            'url',
            'method',
            'statusCode',
            'statusText',
            'operationName',
            'operationType',
        ];
        if (options.httpRequestHeaders) {
            labelNames.push('requestHeaders');
        }
        if (options.httpResponseHeaders) {
            labelNames.push('responseHeaders');
        }
        httpHistogram =
            typeof options.http === 'object'
                ? options.http
                : createHistogram({
                    histogram: new Histogram({
                        name: 'graphql_yoga_http_duration',
                        help: 'Time spent on HTTP connection',
                        labelNames,
                        registers: [registry],
                    }),
                    fillLabelsFn(params, { request, response }) {
                        const labels = {
                            operationName: params.operationName || 'Anonymous',
                            url: request.url,
                            method: request.method,
                            statusCode: response.status,
                            statusText: response.statusText,
                        };
                        if (params?.operationType) {
                            labels.operationType = params.operationType;
                        }
                        if (options.httpRequestHeaders) {
                            labels.requestHeaders = JSON.stringify(headersToObj(request.headers));
                        }
                        if (options.httpResponseHeaders) {
                            labels.responseHeaders = JSON.stringify(headersToObj(response.headers));
                        }
                        return labels;
                    },
                });
    }
    const startByRequest = new WeakMap();
    const paramsByRequest = 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);
            }
        },
        onExecute({ args }) {
            const operationAST = getOperationAST(args.document, args.operationName);
            const operationType = operationAST?.operation;
            const operationName = operationAST?.name?.value;
            paramsByRequest.set(args.contextValue.request, {
                document: args.document,
                operationName,
                operationType,
            });
        },
        onResponse({ request, response, serverContext }) {
            const start = startByRequest.get(request);
            if (start) {
                const duration = Date.now() - start;
                const params = paramsByRequest.get(request);
                httpHistogram?.histogram.observe(httpHistogram.fillLabelsFn(params || {}, {
                    ...serverContext,
                    request,
                    response,
                }), duration);
            }
        },
    };
}