Launch a Dash app in a Google Colab Notebook

To my knowledge there is currently no straightforward way to do this.

Find below a workaround that is similar to setting up Tensorboard (https://www.dlology.com/blog/quick-guide-to-run-tensorboard-in-google-colab/).

Start with a code cell that sets up all things required for this workaround:

# How to run a Dash app in Google Colab

## Requirements

### Install ngrok
!wget https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-linux-amd64.zip
!unzip ngrok-stable-linux-amd64.zip

### Run ngrok to tunnel Dash app port 8050 to the outside world. 
### This command runs in the background.
get_ipython().system_raw('./ngrok http 8050 &')

### Get the public URL where you can access the Dash app. Copy this URL.
! curl -s http://localhost:4040/api/tunnels | python3 -c \
    "import sys, json; print(json.load(sys.stdin)['tunnels'][0]['public_url'])"

### Install Dash
!pip install dash==0.31.1  # The core dash backend
!pip install dash-html-components==0.13.2  # HTML components
!pip install dash-core-components==0.39.0  # Supercharged components
!pip install dash-table==3.1.7  # Interactive DataTable component (new!)

Add another code cell with your Dash app:

## Dash app (https://dash.plot.ly/getting-started)

### Save file with Dash app on the Google Colab machine
%%writefile my_app1.py
import dash
import dash_core_components as dcc
import dash_html_components as html

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div(children=[
    html.H1(children='Hello Dash'),

    html.Div(children='''
        Dash: A web application framework for Python.
    '''),

    dcc.Graph(
        id='example-graph',
        figure={
            'data': [
                {'x': [1, 2, 3], 'y': [4, 1, 2], 'type': 'bar', 'name': 'SF'},
                {'x': [1, 2, 3], 'y': [2, 4, 5], 'type': 'bar', 'name': u'Montréal'},
            ],
            'layout': {
                'title': 'Dash Data Visualization'
            }
        }
    )
])

if __name__ == '__main__':
    app.run_server(debug=True)

In a last code cell you can then start your Dash app (this cell will be busy until you stop the exection and thus, stop your Dash app).

### Run Dash app
!python my_app1.py

To access the Dash app copy & paste the ngrok.io-URL above to a new brower tab (NOT 127.0.0.1:8050) and wait a few seconds.

JupyterDash (the official library for running Dash in notebooks) now has support for running apps on Colab.

You can paste this code inside a colab notebook, and your app will show up inline:

!pip install jupyter-dash

import plotly.express as px
from jupyter_dash import JupyterDash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
# Load Data
df = px.data.tips()
# Build App
app = JupyterDash(__name__)
app.layout = html.Div([
    html.H1("JupyterDash Demo"),
    dcc.Graph(id='graph'),
    html.Label([
        "colorscale",
        dcc.Dropdown(
            id='colorscale-dropdown', clearable=False,
            value='plasma', options=[
                {'label': c, 'value': c}
                for c in px.colors.named_colorscales()
            ])
    ]),
])
# Define callback to update graph
@app.callback(
    Output('graph', 'figure'),
    [Input("colorscale-dropdown", "value")]
)
def update_figure(colorscale):
    return px.scatter(
        df, x="total_bill", y="tip", color="size",
        color_continuous_scale=colorscale,
        render_mode="webgl", title="Tips"
    )
# Run app and display result inline in the notebook
app.run_server(mode='inline')

Here's a GIF of what the output looks like. You can also check out this Colab notebook.

Here's some more useful links:

• v0.3.0 Release note
• JupyterDash Announcement
• Official Repository
• Demo apps using Hugging Face's transformers in Colab

Thank you. Guys, if xhlulu's suggestion doesn't run as expected you can edit the last row like this:

app.run_server(mode='inline',host="0.0.0.0",port=1005)