A general way to run Web Applications on Google Colab

colab_host_webserver.md

Run Web Application on Google Colab

Port Selection

Port	Command
Unused Port	import portpicker port = portpicker.pick_unused_port()
Or
Custom Port	port = 8000
Custom Port	port = 8000 port = 8000

Define IP

select_ip = "0.0.0.0:"+str(port)

Url Generate

Port	Command
As Local	from google.colab import output output.serve_kernel_port_as_window(port)
Or
As Proxy	from google.colab.output import eval_js print(eval_js( "google.colab.kernel.proxyPort(" + str(port) + ")" ))

Start Server

Flask

Set port and run

python3 app.py
or 
!flask run --host $select_ip --port $port

Django

python -m http.server $port
or 
python3 manage.py runserver $select_ip

Full Code: Locally with Custom Port

from google.colab import output

port = 8000
output.serve_kernel_port_as_window(port)
python -m http.server $port

Full Code: Proxy with Unused Port

import portpicker
from google.colab.output import eval_js

port = portpicker.pick_unused_port()
select_ip = "0.0.0.0:"+str(port)

print(eval_js( "google.colab.kernel.proxyPort(" + str(port) + ")" ))
python3 manage.py runserver $select_ip

---

All in one Class

• ServerURL class

from google.colab import output
import portpicker
from google.colab.output import eval_js

class ServerURL:

  def __init__(self,run_type):

    self.run_type = run_type
    self.default_port = 8000
    self.default_ip = "0.0.0.0"

    if self.run_type == "local":
      self.run_local()
    elif self.run_type == "proxy":
      self.run_proxy()
    else:
      print("Error")

  def get_port(self):
    return self.default_port

  def run_local(self):
    output.serve_kernel_port_as_window(self.default_port)

  def run_proxy(self):
    self.default_port = portpicker.pick_unused_port()
    print(eval_js( "google.colab.kernel.proxyPort(" + str(self.default_port) + ")" ))

• driver class

S = ServerURL("local")
port = S.get_port()
flask run --host 0.0.0.0 --port $port

am not able to open admin panel.

from google.colab.output import eval_js print(eval_js("google.colab.kernel.proxyPort(8000)"))

https://us3anlz24pp-496ff2e9c6d22116-8000-colab.googleusercontent.com/admin -- is not working.. any suggestions?

• Did you start your server? Seems working fine in my side.

• If server is on and still doesn't work. Then try running locally instead of proxy

from google.colab import output output.serve_kernel_port_as_window(8000)

If nothing works. Then final solution:

1. Do Local tunneling: ngrok with colab
   or
2. Try Google cloud shell: https://shell.cloud.google.com/ and in shell use "web-preview"

i have no issues accessing the home page. am not able to access django admin panel.

i have taken the project and ran in my local, am able to access admin panel. it is issue from colab.