Reuse TCP connection with node-fetch in node.js - node.js

Question

I am using this function to call an external API
const fetch = require('node-fetch');
fetchdata= async function (result = {}) {
var start_time = new Date().getTime();
let response = await fetch('{API endpoint}', {
method: 'post',
body: JSON.stringify(result),
headers: { 'Content-Type': 'application/json' },
keepalive: true
});
console.log(response)
var time = { 'Respone time': + (new Date().getTime() - start_time) + 'ms' };
console.log(time)
return [response.json(), time];
}
The problem is that i am not sure that node.js is reusing the TCP connection to the API every time i use this function, eventhough i defined the keepalive property.
Reusing the TCP connection can significantly improve response time
Any suggestions will be welcomed.

Answer 1

As documented in https://github.com/node-fetch/node-fetch#custom-agent
const fetch = require('node-fetch');
const http = require('http');
const https = require('https');
const httpAgent = new http.Agent({ keepAlive: true });
const httpsAgent = new https.Agent({ keepAlive: true });
const agent = (_parsedURL) => _parsedURL.protocol == 'http:' ? httpAgent : httpsAgent;
const fetchdata = async function (result = {}) {
var start_time = new Date().getTime();
let response = await fetch('{API endpoint}', {
method: 'post',
body: JSON.stringify(result),
headers: { 'Content-Type': 'application/json' },
agent
});
console.log(response)
var time = { 'Respone time': + (new Date().getTime() - start_time) + 'ms' };
console.log(time)
return [response.json(), time];
}

Answer 2

Here's a wrapper around node-fetch based on their documentation:
import nodeFetch, { RequestInfo, RequestInit, Response } from "node-fetch";
import http from "http";
import https from "https";
const httpAgent = new http.Agent({
keepAlive: true
});
const httpsAgent = new https.Agent({
keepAlive: true
});
export const fetch = (url: RequestInfo, options: RequestInit = {}): Promise<Response> => {
return nodeFetch(url, {
agent: (parsedURL) => {
if (parsedURL.protocol === "http:") {
return httpAgent;
} else {
return httpsAgent;
}
},
...options
});
};

Answer 3

Keep-alive is not enabled for the default used agent and is not currently implemented into node-fetch directly, but you can easily specify a custom-agent where you enable the keep-alive option:
const keepAliveAgent = new http.Agent({
keepAlive: true
});
fetch('{API endpoint}', {
...
agent: keepAliveAgent
});

Answer 4

here is a wrapper for node-fetch to add a keepAlive option, based on Ilan Frumer's answer
// fetch: add option keepAlive with default true
const fetch = (function getFetchWithKeepAlive() {
const node_fetch = require('node-fetch');
const http = require('http');
const https = require('https');
const httpAgent = new http.Agent({ keepAlive: true });
const httpsAgent = new https.Agent({ keepAlive: true });
return async function (url, userOptions) {
const options = { keepAlive: true };
Object.assign(options, userOptions);
if (options.keepAlive == true)
options.agent = (parsedUrl => parsedUrl.protocol == 'http:' ? httpAgent : httpsAgent);
delete options.keepAlive;
return await node_fetch(url, options);
}
})();
const response = await fetch('https://github.com/');
const response = await fetch('https://github.com/', { keepAlive: false });