How to use Flask in Google Colaboratory Python Notebook?

Question

I am trying to build a website using Flask, in a Google Colab Python notebook. However, running a regular Flask code that works on a regular Python, fails to work on Google

Answer 1

The server code:

import socket
print(socket.gethostbyname(socket.getfqdn(socket.gethostname())))

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

import threading
threading.Thread(target=app.run, kwargs={'host':'0.0.0.0','port':80}).start() 

Client code:

import requests
r = requests.get("http://172.28.0.2/")
print(r.status_code)
print(r.encoding)
print(r.apparent_encoding)
print(r.text)

To restart Flask you may click menu: runtime->restart runtime

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Answer 2

!pip install flask-ngrok


from flask import Flask
from flask import request
from flask_ngrok import run_with_ngrok

app = Flask(__name__)
run_with_ngrok(app)  # Start ngrok when app is run

# for / root, return Hello Word
@app.route("/")
def root():
    url = request.method
    return f"Hello World! {url}"

app.run()

https://medium.com/@kshitijvijay271199/flask-on-google-colab-f6525986797b

Answer 3

from flask_ngrok import run_with_ngrok
from flask import Flask

app = Flask(__name__)

run_with_ngrok(app)  
@app.route("/")

def home():
    return f"Running Flask on Google Colab!"

app.run()

Answer 4

The server side code AKA: backend

from flask import Flask
import threading

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

threading.Thread(target=app.run, kwargs={'host':'0.0.0.0','port':6060}).start()

Rendering the server inside the colab

import IPython.display

def display(port, height):
    shell = """
        (async () => {
            const url = await google.colab.kernel.proxyPort(%PORT%, {"cache": true});
            const iframe = document.createElement('iframe');
            iframe.src = url;
            iframe.setAttribute('width', '100%');
            iframe.setAttribute('height', '%HEIGHT%');
            iframe.setAttribute('frameborder', 0);
            document.body.appendChild(iframe);
        })();
    """
    replacements = [
        ("%PORT%", "%d" % port),
        ("%HEIGHT%", "%d" % height),
    ]
    for (k, v) in replacements:
        shell = shell.replace(k, v)

    script = IPython.display.Javascript(shell)
    IPython.display.display(script)

display(6060, 400)