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

Prometheus plugin for GraphQL Yoga.

import { getOperationAST } from 'graphql';
import { register as defaultRegistry } from 'prom-client';
import { createCounter, createHistogram, createSummary, usePrometheus as useEnvelopPrometheus, } from '@envelop/prometheus';
export { createCounter, createHistogram, createSummary, };
export function usePrometheus(options) {
    const endpoint = options.endpoint || '/metrics';
    const registry = options.registry || defaultRegistry;
    let httpHistogram;
    function labelExists(label) {
        if (options.labels?.[label] == null) {
            return true;
        }
        return options.labels[label];
    }
    if (options.http) {
        const labelNames = ['method', 'statusCode'];
        if (labelExists('operationName')) {
            labelNames.push('operationName');
        }
        if (labelExists('operationType')) {
            labelNames.push('operationType');
        }
        httpHistogram =
            typeof options.http === 'object'
                ? options.http
                : createHistogram({
                    registry,
                    histogram: {
                        name: typeof options.http === 'string' ? options.http : 'graphql_yoga_http_duration',
                        help: 'Time spent on HTTP connection',
                        labelNames,
                    },
                    fillLabelsFn(params, { request, response }) {
                        const labels = {
                            method: request.method,
                            statusCode: response.status,
                        };
                        if (labelExists('operationType') && params.operationType) {
                            labels.operationType = params.operationType;
                        }
                        if (labelExists('operationName')) {
                            labels.operationName = params.operationName || 'Anonymous';
                        }
                        return labels;
                    },
                });
    }
    const startByRequest = new WeakMap();
    const paramsByRequest = new WeakMap();
    return {
        onPluginInit({ addPlugin }) {
            addPlugin(useEnvelopPrometheus({ ...options, registry }));
        },
        onRequest({ request, url, fetchAPI, endResponse }) {
            startByRequest.set(request, Date.now());
            if (endpoint && url.pathname === endpoint) {
                return registry.metrics().then(metrics => {
                    endResponse(new fetchAPI.Response(metrics, {
                        headers: {
                            'Content-Type': registry.contentType,
                        },
                    }));
                });
            }
            return undefined;
        },
        onParse() {
            return ({ result: document, context: { params, request } }) => {
                const operationAST = getOperationAST(document, params.operationName);
                paramsByRequest.set(request, {
                    document,
                    operationName: operationAST?.name?.value,
                    operationType: operationAST?.operation,
                });
            };
        },
        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);
            }
        },
    };
}