Deploying a Plotly Dash Webapp on Render: A Step-by-Step Guide¶

I like to create web applications in Python, especially using the Plotly Dash framework. One of my favorite projects is a Sudoku Solver that’s powered by Mixed-Integer Linear Programming (check it out at sudoku.quiradata.com). I understand the excitement of bringing a project to life on the web. In this guide, I’ll walk you through the process I used to deploy my Sudoku app on Render.

Prerequisites¶

Make sure you have the following:

A Render account: Sign up at render.com
A GitHub account and repository: This should contain your Python Dash application project

Update Python Code and Create requirements.txt¶

Setting Up intro point¶

Locate the section of your python application file where the app variable is defined. It should look something like this:
1
app = dash.Dash(__name__)
Add the following line immediately after the app definition:
2
server = app.server

This exposes your Dash app’s Flask server instance, which is necessary for deployment.

Creating/Updating `requirements.txt`¶

In the root directory of your repository, create a file named requirements.txt. You can use pipreqs to generate the requirements file based on imports in project. For example:
requirements.txt
```
numpy==1.26.4
pandas==2.2.1
dash==2.17.1
Pyomo==6.6.0
highspy~=1.7.1.dev1
```
Include gunicorn at the end of the requirements.txt file. Gunicorn is a Python HTTP server that efficiently handles web requests.
requirements.txt
```
numpy==1.26.4
pandas==2.2.1
dash==2.17.1
Pyomo==6.6.0
highspy~=1.7.1.dev1
gunicorn
```

Setting Up a New Web Service on Render¶

Log in to Render and navigate to your dashboard.
Click +New / Web Service.
Provide the URL of your Public GitHub repository containing the Dash app.
Configure the service by:
Giving your service a unique name.
Language: Python 3
Branch: The Git branch to build and deploy. In my case master
Build Command: Render runs this command to build your app before each deploy
```
$ pip install -r requirements.txt
```
Start Command: Render runs this command to start your app with each deploy
```
$ gunicorn app:server
```
Hit Deploy Web Service to finalize the setup.

You're Live!¶

Render will now build and deploy your application. This may take a few minutes.
Once deployment is complete, you’ll see a live link to your application.

Your Dash app is now live on Render and accessible from anywhere.