Getting TypeError: Converting circular structure to JSON on express app

[ahsannaseem]

Hi, so we are trying to use prometheus-api-metrics following as mentioned in official doc. But getting circular structure to json error.

TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'Socket'
    |     property 'parser' -> object with constructor 'HTTPParser'
    --- property 'socket' closes the circle
    at JSON.stringify (<anonymous>)
    at /Users/ahsannaseem/coding/project-repo/node_modules/prometheus-api-metrics/src/metrics-middleware.js:14:61

code in application.ts

require("dotenv-extended").load();
process.env.NODE_ENV !== "development" ? require("newrelic") : null;
import * as loggerConfig from "./config/logger-config";
loggerConfig.initialize();
import * as bodyParser from "body-parser";
import { registerConfigsAndLoad, container, createDatabasePools } from "./config/inversify.config";
import { loadAndSetScheduleForPeriodicData } from "./services/periodic-loaded-config";
import { Server } from "net";
//declare prometheus-api-metrics
import * as apiMetrics from "prometheus-api-metrics";
let isGlobalsInitilizingStarted: boolean = false;
let isGlobalsInitilized: boolean = false;

export async function initGlobals() {
    if (isGlobalsInitilizingStarted)
        throw new Error("Initilizing is already started.");
    isGlobalsInitilizingStarted = true;
    console.log("Initilized global variables.");
    await require("./config/container-config").configure();
    await registerConfigsAndLoad();
    createDatabasePools();
    // some init can be done in parallel
    await Promise.all([
        require("./config/redis-config").configure(),
        loadAndSetScheduleForPeriodicData()
    ]);

    isGlobalsInitilized = true;
}

export async function startSqsEventListener() {
    if (!isGlobalsInitilized) {
        throw new Error("Globals are noit initilized. Run initGlobals() first.");
    }
    await require("./config/sqs-config").listen();
}

export async function startWebServer(): Promise<Server> {
    if (!isGlobalsInitilized) {
        throw new Error("Globals are noit initilized. Run initGlobals() first.");
    }

    // start http server
    const app = require("express")();
    app.use(bodyParser.json());
// consume api-metrics
    app.use(apiMetrics);
    const routeConfig = require("./config/route-config");
    routeConfig.configure(app);
    const port = process.env.PORT || 3000;
    return app.listen(port, function () {
        console.log("service listening on port", port);
    });
}

[kobik]

Hi @ahsannaseem, when do you get this error? on incoming request?

have you called init first?