I created a simple web app as described in this tutorial and hosted it on a linux VM using Google's Compute Engine.
Unfortunately when I close my SSH connection after spinning up the flask app, the external IP Address and functionality does not persist.
How do I get it to stay up as long as my VM is up and running? Is this an issue with where the app is located in my vm (ex: www/ folder vs the /user/ folder)?
The answers above are both great and both work. For the next person that is relatively new to VM/Google Compute/Cloud here is exactly how I used screen. I think this is the simplest/ best solution for just learning/ getting something stood up quickly.
Once you are in your VM, first create a screen.
screen -S <screen name>
In my case, I used
screen -S one
Now your terminal will most likely clear as you are in your screen, a new process window on the same VM. This is where we can run our flask code.
Now implement your flask/ web server code/ whatever.
export FLASK_APP=main.py
flask run
Now I am able to hit my web server link that pops up. Now you can close out of this terminal/ terminate my ssh connection, the web app is still live.
Next time I ssh in I can simply use screen -ls to show my list of available screens. It will also show the status of your screens.
googleUserName@one:~$ screen -ls
There is a screen on:
761.one (02/01/2018 06:58:56 PM) (Detached)
Now I can reconnect to it, I just specify the screen by using -r for reconnect.
screen -r <screen name>
In my case
screen -r one
When I reconnect my webserver is still running and shows all my outputs and traffic I would expect as if I never closed it.
Now if you want to bounce back and forth between your screen and your normal ssh connection, you can detach, -d, from it. (Here you do not have to specify the screen name, 'one' in my case, because you are currently in the screen, and will detach from the current.
screen -d
Some closing remarks...
I do not know if you can create a screen within a screen.
I do not know how sustainable this solution is/ if it is recommended. But screen works fine for my use cases.
Here is the code I am running in my main.py flask application.
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
return "Hello World!"
You can find it here
The tutorial I used getting started with google compute engine, set up, and web servers is here.
You'll need to run the app in a background process or in screen or tmux. This is a good primer.
For more details on how to use screen, you can check this article.
Additionally, you can check this discussion on a similar concern as well.
It's because you're running as a user. A few minutes after closing your ssh connection, your session will close and the process will be killed. You can either run it has a startup script (https://cloud.google.com/compute/docs/startupscript#startupscriptrunninginstances) or startup cron job as root.
