11 releases

✓ Uses Rust 2018 edition

0.11.10 Mar 21, 2019
0.11.9 Mar 18, 2019
0.11.7 Feb 26, 2019

#10 in Configuration

Download history 45/week @ 2019-02-07 5/week @ 2019-02-14 29/week @ 2019-02-21 24/week @ 2019-02-28 1/week @ 2019-03-07 48/week @ 2019-03-14 69/week @ 2019-03-21 13/week @ 2019-03-28 16/week @ 2019-04-04 3/week @ 2019-04-11 11/week @ 2019-04-18

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Jelly Schema

Build Status Current Release License Issues

an open source 📡 project by balena.io

Provides facilities to:

  • transform Jelly Schema into the JSON Schema & UI Schema objects with custom extensions
  • parse Jelly Schema
  • validate JSON data against Jelly Schema

Current crate status is experimental.


jellyschema crate is one small piece of the balena.io configuration project. This project has no public / open specification yet, but we're working on it and it will be public once finished.

Supported platforms

This library is written in the Rust language and can be used:




Add as a dependency to your Cargo.toml:

jellyschema = "0"

Evaluate simple JSON:

let input_schema: serde_yaml::Value = serde_yaml::from_str(

let (json_schema, ui_object) = Generator::with(input_schema)?.generate();


Install via npm

npm install --save jellyschema

Generate simple JSON Schema & UI Object Schema:

const jellyschema = require('jellyschema');

const initialValue = `
title: demo
version: 1
  - network:
      title: Network
        - ssid:
            title: Network SSID
            type: string
            minLength: 1
            maxLength: 32
        - passphrase:
            title: Network Key
            type: password
            minLength: 8

var schema = new jels.JellySchema(initialValue);
const result = schema.jsonAndUiSchema();
console.log(JSON.stringify(result, null, 2));

console.log(schema.validate({network: { ssid: 'foo', passphrase: 123 }}));

An example of using this module in nodeJS is available in the examples/node folder:

cd examples/node
npm install
npm start

An example of using this module in the browser is available in the examples/browser folder:

cd examples/browser
npm install
npm start

Open localhost:8080 in your browser.


If you're having any problem, please raise an issue on GitHub or contact us, and the balena.io team will be happy to help.


jellyschema is open source software, and may be redistributed under the terms specified in the license.


~122K SLoC