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:

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 --autoreload

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 --autoreload

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 --autoreload flag.

  • How to stop the Panel server with CTRL+C.

Resources#

Tutorials#

How-to#

Keep exploring and building with Panel! 🚀