I am deploying my node.js program on a remote machine (Ubuntu 14.04) and the program terminates after ssh session even if I deploy it as background process.
node app.js &
I understand that using forever can solve this, which I have tried and it pretty much works. There is already a thread here that describes the good solutions to it, and there are many other threads all describes good tools and solutions for it.
But, I would like to understand why does the node.js process stops at
first place even if it runs as background process?
Since you are connecting through SSH all the processes belong to that session.
Unless specified by a command like
nohup
or no hang up for short, all the processes that belong to your session through SSH will die with the session.
It's like logging in with a user opening chrome and logging out. The chrome thread will be release once the owner was logged out.
Related
I'm trying to create a simple Twitter bot to learn some Node.js skills.
It works fine on my local computer. I start the script with node bot.js and then close it with Ctrl + C.
I've uploaded the files to a server (Krystal hosting). I've ssh'd into the server and then used $ source /home/[username]/nodevenv/twitterbot/10/bin/activate. Which I think puts me into a Node environment (I'm not really clear what is happening here).
From here I can run node bot.js. My Twitter bot runs fine and I can leave the terminal. What I've realised now is that I don't know how to stop this script.
Can someone explain how I should be doing this? Is there a command I can enter to stop the original bot.js process? Since looking into this it looks like perhaps I should have used something like pm2 process manager. Is this correct?
Any pointers would be much appreciated.
Thanks,
B
You can kill it externally by nuking the process from an OS command line or in an OS GUI (exact procedure varies by OS). Ctrl-C from the shell is one version of this, but it can be done without the command shell that it was started in too by nuking the process directly.
Or, you can add a control port (a simple little http server running on a port only accessible locally) that accepts commands that let you do all sorts of things with the server such as extract statistics, shut it down, change the configuration, tell it to clear caches so content updates take effect immediately, etc... Shutting down the server this way allows for a more orderly shut-down from code within the server. You can even stop accepting incoming connections, but wait for existing http connections to complete before shutting down, close databases normally, etc...
Or, you can use a monitoring program such as PM2 or forever that in addition to restarting the server automatically if it should ever crash, they also offer commands for shutting it down too (which will just send it certain signals kind of like Ctrl-C does).
A process has been started remotely through a SSH session. The output stream (text) is displayed OK thru SSH. I would like to display the results locally without interrupting the running process.
Is there a way to attach to a running process and 'piggyback' a stream?
A Linux-only solution is acceptable.
Thanks!
Use reptyr:
reptyr is a utility for taking an existing running program and
attaching it to a new terminal. Started a long-running process over
ssh, but have to leave and don't want to interrupt it? Just start a
screen, use reptyr to grab it, and then kill the ssh session and head
on home.
Or retty:
retty is a tiny tool that lets you attach processes running on other
terminals.
Excuse the noob question but I am having some trouble with a Play Webserver. Currently I start up the app using 'activator run', which as I understand is the dev method of starting this up.
The actual webserver is located on a remote azure cloud VM so I have no gui access and therefore can't leave the activator web interface running to keep the process alive.
The trouble I have is that when my SSH session dies so does the webserver.
I have tried '&' to background the process, and also nohup with no success. In either of those cases the webserver does not even start.
Any advice would be greatly appreciated.
Thanks.
You can use Ctrl+D to exit the play console while keeping the web server process running.
Source: https://www.playframework.com/documentation/2.2.x/Production
Is there a universally accepted means of deamonizing (and of course, later communicating through signals or some abstraction thereon) a node script?
That is, is there a Node equivalent of:
if (fork())
// parent process, die
exit(1);
// we're a daemon
The following is a list of ways to run Node as a background daemon on
different platforms:
nodejs-autorestart manages a Node instance on Linux which uses Upstart (Ubuntu, Debian, and so on).
fugue watches a Node server, restarting it if it crashes.
forever is a small commandline Node script which ensures a script will run "forever".
node-init is a Node script which turns your Node application into a LSB-compliant init script. LSB being a specification of Linux
compatibility.
There is not a built-in way to do this in Node. Take a look at Writing Daemon's in JavaScript with Node.js for one implementation (warning: this is relatively old and Node moves fast--I haven't tested it. :)
Upstart works well for me, though I'm having an issue when I serve over https. Here's the tutorial I used:
http://kevin.vanzonneveld.net/techblog/article/run_nodejs_as_a_service_on_ubuntu_karmic/
You can use node's process object to send/handle signals.
As others have pointed out there really isn't a way to do this in Node directly. You really need to run it using foreverjs. The reason you need to run it using a monitor like forever, is because error thrown by your code will often result in the entire Node process to quit and exit. A monitor will look for this occurring and restart the process immediately.
It is also important to note that while the process is restarting, your server will not respond to request so plan ahead if you expect this to be a problem and make sure that you have a few servers processes running under a load-balancer.
I am trying to set up a development environment for node.js. I assumed at first that it requires something similar to the traditional, "localhost" server approach. But I found myself at a loss. I managed to start a node.js hello world app from the terminal. Which doesn't looked like a big deal - having to start an app from the console isn't that hard. But, after some tweaking, I found out that the changes aren't shown in the browser immediately - you need to "node [appName here]" it again to run.
So, my question is:
Is there a software or a tutorial on how to create a more "traditional" development server on your local machine? Along with port listening setup, various configurations, root directories etc (things that are regular in stacks like XAMMP, BitNami or even the prepackaged Ubuntu LAMP). Since I'm new at node.js, I can't really be sure I'm even searching for the right things on google.
Thanks.
Take a look at :
https://github.com/remy/nodemon
it'll allow you to do - nodemon app.js
and the server will restart automatically in case of failure.
To do this I built a relatively small tool in NodeJS that allows me to start/stop/restart a NodeJS child process (which contains the actual server) and see/change configuration option and builds/versions of the application, with admin options available on a different tcp port. It also monitors said child process to automatically respawn it if there was a error (and after x failed attempts stops trying and contacts me).
While I'm prohibited from sharing source code, this requires the (built-in) child_process module, which has a spawn method that returns a child process I guess, which contains a pid (process id) which you can use with the kill method to kill said child process. Instead of killing it you could also work with SIGINT an catch it within your child application to first clean up some stuff and then exit. It's relatively easy to do.
Some nice reading material regarding this.
http://nodejs.org/docs/v0.5.5/api/child_processes.html