How to restart Node.js server from code? For example, if using expressjs framework,
app.get('/restart', function (req, res, next) {
//Code to restart a server
})
I want to restart server from app like this, without going to console etc. How to do it?
I use forever in order to start and monitoring application.
So the restart function like this:
app.get('/restart', function (req, res, next) {
process.exit(1);
});
After the shutdown of server, forever will restart service.
console:
Express server listening on port 3000 in development mode
error: Forever detected script exited with code: 1
error: Forever restarting script for 2 time
Express server listening on port 3000 in development mode
By combining npm restart and child_process.exec() it appears possible to restart the server programmatically. And since it allows for several scripts to be run for stopping, restarting, and starting this option would work even for multi-process servers or otherwise complex servers where simply calling process.exit() isn't viable.
You can mark a child-process as detached which I believe makes it survive past the parent's destruction. So if you use that, with a "sleep" command at the start of the command (in case concurrent running is an issue), it should work.
So presumably something like this (untested):
const newProcessInstance = spawn(process.argv[0], process.argv.slice(1), {
detached: true,
stdio: 'ignore', // not sure if this is needed
});
Related
I am trying to create some setup and teardown logic for an expressjs server. Here's my entry code:
import fs from "fs";
import express from "express";
import { setRoutes } from "./routes";
let app = express();
const server = app.listen(8080, function () {
console.log(`š§ Mock Server is now running on port : ${8080}`);
});
app = setRoutes(app);
function stop() {
fs.rmdirSync("./uploads", { recursive: true });
fs.mkdirSync("uploads");
console.log("\nš§¹ Uploads folder purged");
server.on("close", function () {
console.log("ā¬ Shutting down server");
process.exit();
});
server.close();
}
process.on("SIGINT", stop);
// Purge sw images on restart
process.once("SIGUSR2", function () {
fs.rmdirSync("./uploads/swimages", { recursive: true });
console.log("š§¹ Software Images folder purged");
process.kill(process.pid, "SIGUSR2");
});
The npm script to start this up is "start": "FORCE_COLOR=3 nodemon index.js --exec babel-node".
The setup and restart logic works as expected. I get š§ Mock Server is now running on port : 8080 logged to console on startup. When I save a file, nodemon restarts the server, and the code in process.once is executed. When I want to shut it all down, I ctrl + c in the terminal. The cleanup logic from within the stop function is run. However, the process bever fully exits. In the terminal, am still stuck in the process, and I have to hit ctrl + c again to fully exit the process. It looks like this:
As far as I know there are no open connections (other questions mentioned that if there is a keep-alive connection still open, the server will not close properly, but as far as I can tell, that is not the case). I have tried different variations of server.close(callback), server.on('close', callback), process.exit(), process.kill(process.pid), etc, but nothing seems to fully exit the process.
Note that if I simply run node index.js, I do not have this issue. The cleanup logic runs, and the process exits to completion without issue. It seems to be an issue when using nodemon only.
I don't want other developers to have to wait for cleanup logic to run and then hit ctrl + c again. What am I missing to run my cleanup logic and fully exit the process in the terminal?
There is an open connection for sure. Check this package that can tell you which one: https://www.npmjs.com/package/wtfnode
I have a problem that when I want to turn on my discord bot on my server that uses cPanel, I can't get it to work from the node.js control panel without putting the shell command node index.js into the package.json file and using the run script function of the panel. the problem with this is that the only way to stop the bot is to use the eval command on discord, since I don't have proper terminal access.
In addition to what #Verdigris answered above, you can use Glitch too, just make sure to use Runtime Bot so you can keep your Discord bot up 24/7.
Important: code to add on your main node.js file:
const http = require('http');
const express = require('express');
const app = express();
app.get("/", (request, response) => {
console.log(Date.now() + "Ping Received");
response.sendStatus(200);
});
app.listen(process.env.PORT);
setInterval(() => {
http.get(`http://${process.env.PROJECT_DOMAIN}.glitch.me/`);
}, 280000);
And as always, cheers.
On cPanel you will never have full terminal access, so what I suggest you do is just keep the NPM start script, then create a command for the bot that issues the process.exit() function. This function essentially stops the entire NodeJS Process. If you are looking for an alternative that provides full terminal access I recommend buying a cheap VPS from a decent provider such as OVH.
If your cPanel account has a in-browser terminal, you can enter the virtual environment by pasting the command that appears at the top of the Node.js control panel into there. It is something like:
source ~/nodevenv/<name_of_node_application>/10/bin/activate && cd ~/<path_to_node_application>
You will then have access to node and npm, and can then start your discord bot like you normally would like:
node <name_of_node_application> &
and kill it by running kill -TERM with node's pid, from ps -ax.
However, you can't reliably use the Node.js panel to stop a daemon script, as described here:
cpanel node.js Can't acquire lock for app: app
I'm trying to use pm2 to run my node app as a service.
Right now, starting and stopping the app works. However, I want to do a graceful shutdown.
My app already listens for SIGINT, shutdowns the server and then exits the process. However, trying to put pm2 to send the SIGINT, just causes the app to restart, like if pm2 was killing and starting it again.
This is how I create the process:
pm2 start server.js --name ProcessName --silent --kill-timeout 3000
Here's my app's code for listening the SIGINT:
process.on("SIGINT", function () {
//graceful shutdown
server.end().then(() => {
process.exit();
}).catch((err) => {
console.error(err);
});
});
Then to shutdown the app using pm2, I'm running:
pm2 sendSignal SIGINT ProcessName
Which, again, restarts the app.
Reading over pm2 docs, I found that pm2 will also send a shutdown event to the app, so I added:
process.on('message', function(msg) {
if (msg == 'shutdown') {
server.end().then(() => {
process.exit();
}).catch((err) => {
console.error(err);
});
}
});
Which isn't working either.
Any idea how to solve this?
Thanks!
If you haven't solved it yet...
Based on the information you provided, I assume you are running it on Windows.
Your app cannot catch SIGINT sent by PM2 on Windows.
shutdown message works on windows too, but it is sent only by gracefulReload command.
(update)
These are not complete solutions, but might be helpful (hopefully...)
sendSignal command calls process.kill() eventually, and some of these signals might work (haven't tried).
I also found the below method. This can gracefully shutdown a process without restarting only if autorestart option is turned off.
And then your clusters will not reload in case of an accident, so it might not be what you want though...
pm2 lets you send a custom message (reference).
Put the code below in a new file:
var pm2 = require('pm2');
var id = process.argv[2];
pm2.connect(() => {
pm2.sendDataToProcessId({
type: 'shutdown',
data:{some: 'data'},
id: id,
topic: 'some topic'
}, (err, res) => {
console.log('message sent');
pm2.disconnect();
if(err) throw err;
})
});
Modify the part that listens the shutdown message like below:
process.on('message', function(msg){
if(msg == 'shutdown' || msg.type == 'shutdown'){
// code to clean up
}
});
And run the first file with node with id of the cluster you want to shutdown as an argument.
The reason for extra msg.type == 'shutdown' in the condition is that pm2.sendDataToProcessId() requires the argument to be an object with those keys, and does not accept simple shutdown string.
In general pm2 stop is the right way to stop your application. However if you run appliation inside of the Docker you need to use pm2-runtime instead of pm2 which is a part of pm2 npm package and passes system SIGINT to all child processes. See http://pm2.keymetrics.io/docs/usage/docker-pm2-nodejs
Catching the sigint and exiting gracefully should work in your first example.
To actually stop the server, use pm2 stop instead of pm2 sendSignal SIGINT ProcessName.
See http://pm2.keymetrics.io/docs/usage/signals-clean-restart/
I've been browsing around but to no success. I've found some npm packages like nodemon and forever but documentation doesn't explain how to call a restart inside the script properly.
I've found this code snippet on another question but I'm not using Express or other frameworks since the script is using a pulling service not a response one.
This is code I've made so far using internal Node.js dependencies but no luck.
'use strict'
process.on('uncaughtException', (error) => {
console.error('Global uncaughtException error caught')
console.error(error.message)
console.log('Killing server with restart...')
process.exit(0)
})
process.on('exit', () => {
console.log('on exit detected')
const exec = require('child_process').exec
var command = 'node app.js'
exec(command, (error, stdout, stderr) => {
console.log(`error: ${error.message}`)
console.log(`stdout: ${stdout}`)
console.log(`stderr: ${stderr}`)
})
})
setTimeout(() => {
errorTriggerTimeBomb() // Dummy error for testing triggering uncaughtException
}, 3000)
Just to note I'm running the server on Termux, a Linux terminal app for android. I know it's better to run from desktop but I'm always at a WiFi or mobile data area and that I don't like leaving my PC on overnight.
A typical restart using something like nodemon or forever would be triggered by calling process.exit() in your script.
This would exit the current script and then the monitoring agent would see that it exited and would restart it for you. It's the same principal as if it crashed on its own, but if you're trying to orchestrate it shutting down, you just exit the process and then the monitoring agent will restart it.
I have a home automation server that is being monitored using forever. If it crashes forever will automatically restart it. I also have it set so that at 4am every morning, it will call process.exit() and then forever will automatically restart it. I do this to prevent any memory leak accumulation over a long period of time and 30 seconds of down time in the middle of the night for my application is no big deal.
First i installed the node js with webmatrix and ran a sample node js app. the app was assigned a random port. http://localhost:62369/. After that i installed the express module. As said in their doc. i wrote,
var app = express();
app.get('/',function (req, res) {
res.send('hello world!!');
})
app.listen(3000);
Then i restarted the server. The launched browser was still pointing to http://localhost:62369/ instead of port 3000. Moreover http://localhost:3000/ was not working.
I suggest you to run this code so you can see if you have any problem on saving the code with your IDE:
var app = express(),
port = 4555;
app.get('/',function (req, res) {
res.send('hello world!!');
})
console.log("Server is running on " + port);
app.listen(port);
After that, you need to change the port variable only. It's helpful if you comment what you see after running this code on the console.
make sure that you've saved your code in your file (open it with another editor, maybe something's wrong with your editor), close the command line window and open it again. try to run server. I'm sure the problem is not because of node or express. Try to check everything again.
And also run your server with command line:
cd path/folder
node myFile
I don't know what are you using to run server, but if it's something with UI (in comments you mentioned a click) it can cache your code or something like that. So it's safer to run with commend line.