Build Hello World App#

Welcome to the “Build Hello World App” tutorial! Get ready to dive into the world of Panel and serve your very first app.

Serve the App#

Let’s get started by serving our simple Hello World app using Panel. Choose a tab below to continue:

Script

In this section, we’ll create the simplest Panel .py app:

import panel as pn

pn.extension()

pn.panel("Hello World").servable()

Note

Here’s a breakdown of the code:

panel: The Panel python package, conventionally imported as pn.
pn.extension(): Loads javascript dependencies and configures Panel.
pn.panel(...): Creates a displayable Panel component.
.servable(): Displays the component in a server app.

Copy the code into a file named app.py and save it. Then, run the Panel server in your terminal with:

panel serve app.py --dev

Notebook

In this section, we’ll create the simplest Panel Notebook app:

import panel as pn

pn.extension()

pn.panel("Hello World").servable()

Note

Here’s what the code does:

panel: The Panel python package, conventionally imported as pn.
pn.extension(): Loads the pyviz_comms notebook extension, loads javascript dependencies and configures Panel.
pn.panel(...): Creates a displayable Panel component, which can be directly displayed in the notebook.
.servable(): Displays the component in a server app.

Copy the above code cells into a clean notebook named app.ipynb. Run the cells and save the notebook as app.ipynb.

Then, run the Panel server in your terminal with:

panel serve app.ipynb --dev

Upon successful startup, you’ll see the server’s URL in the terminal.

2024-01-17 21:05:32,338 Starting Bokeh server version 3.3.3 (running on Tornado 6.4)
2024-01-17 21:05:32,339 User authentication hooks NOT provided (default user enabled)
2024-01-17 21:05:32,342 Bokeh app running at: http://localhost:5006/app
2024-01-17 21:05:32,342 Starting Bokeh server with process id: 42008

Open your browser at that URL to view the app. It should look like

Panel serve app .

Play around with the app by modifying the "Hello World" text, saving the file and observe how it updates in real-time. To stop the server, simply press CTRL+C in the terminal.

Recap#

Congratulations on serving your first Panel app! Let’s recap what we’ve learned:

How to serve a Python script or Notebook using panel serve app.py or panel serve app.ipynb, respectively.
How to enable auto reload with the --dev flag.
How to stop the Panel server with CTRL+C.

Build Hello World App#

Serve the App#

Recap#

Resources#

Tutorials#

How-to#