Viola apps

Environment requirements

Your conda environment (used in JHub Apps Launcher's App creation form) must have the following packages for successful app deployment:

• jhsingle-native-proxy >= 0.8.2
• voila >= 0.5.6
• Other libraries used in the app

note

In some cases, you may need ipywidgets

Example application

To deploy the Voila Basic Example using JHub Apps, you can use the following code and environment:

Code (Jupyter Notebook)

In a Jupyter Notebook, copy the following lines of code into a cell.

voila-basic-slider.ipynb

import ipywidgets as widgets

slider = widgets.FloatSlider(description='x')
text = widgets.FloatText(disabled=True, description='x^2')

def compute(*ignore):
    text.value = str(slider.value ** 2)

slider.observe(compute, 'value')

slider.value = 4

widgets.VBox([slider, text])

You will see a basic slider app as shown in this screenshot:

Environment specification

Use the following spec to create a conda environment wherever JHub Apps is deployed. If using Nebari, use this spec to create an environment with conda-store.

channels:
  - conda-forge
dependencies:
  - ipywidgets
  - jhsingle-native-proxy>=0.8.2
  - pandas
  - python
  - pip
  - pip:
      - voila==0.5.6
  - ipykernel

note

When viola (>=0.5.6) is available on Conda Forge, it can be moved outside of the pip section of the dependencies

Next steps

✨ Launch app →