JSON to Variables Setter

Project Info

Overview

JSON to Variables Setter (json2vars-setter) is a GitHub Action that parses a JSON file and sets its values as output variables in GitHub Actions workflows. This action streamlines the management of matrix testing configurations and other workflow variables, making your CI/CD processes more maintainable and adaptable.

By centralizing your configuration in JSON files, you gain the ability to easily manage and update testing environments across multiple workflows, reducing duplication and maintenance overhead.

Table of Contents

• JSON to Variables Setter
  • Overview
  • Table of Contents
  • Key Features
  • Supported Matrix Components
  • Sample Workflows
  • Quick Start
  • Components
  • Documentation
  • License

Key Features

• JSON Parsing: Convert JSON files into GitHub Actions output variables for use in your workflows
• Dynamic Version Management: Automatically update your testing matrix with latest language versions from official sources
• Version Caching: Cache version information to reduce API calls and improve workflow performance
• Support for Multiple Languages: Compatible with Python, Ruby, Node.js, Go, Rust, PHP, .NET (C#), Java, Deno, Bun, Zig, Elixir, Dart, Swift, Julia, Crystal, Haskell, OCaml, Kotlin, Flutter, and the Clang/LLVM and GCC C++ compilers
• Flexible Configuration: Maintain a single source of truth for your matrix testing environments

Supported Matrix Components

Languages	Actions	Example Test Status

📖 Per-language details — supported OS, versions, and the setup action each example drives — are on the Languages section of the documentation.

Sample Workflows

Beyond the per-language tests above, these runnable use-case samples live in this repository and execute on real GitHub Actions. The green badge is proof you can reproduce the result, then copy the files into your own project — no local setup required to gain confidence.

Use case	Status	What it demonstrates	Files
Single source of truth		One JSON parsed once, then consumed by an independent test matrix and a separate lint job — define versions in one place, use them everywhere
Monorepo		Several projects in one repo, each with its own matrix JSON (Python backend + Node.js frontend) and an independent test matrix
Template from cache		Generate a matrix from an existing version cache with no API calls (template-only), trimmed via output-count
Version cache		Drive a multi-version matrix from a committed cache (use-cache) — zero API calls on a cache hit, auto-refresh when cache-max-age is exceeded
Dynamic update (scheduled)		Weekly scheduled maintenance: fetch the latest language versions from the live API (update-matrix) and rebuild the matrix — side-effect-free (no commit)
Conditional matrix		Pick the matrix by event — a light, fast matrix on pull requests and the full cross-OS matrix on schedule / dispatch
Reusable workflow		Define the matrix once in a workflow_call library and consume its outputs from a caller — maintain the version set in one place

Quick Start

Note

See Basic Usage Examples for details.

jobs:
  set_variables:
    runs-on: ubuntu-latest
    outputs:
      os: ${{ steps.json2vars.outputs.os }}
      versions_python: ${{ steps.json2vars.outputs.versions_python }}
      ghpages_branch: ${{ steps.json2vars.outputs.ghpages_branch }}
    steps:
      - name: Checkout repository
        uses: actions/checkout@v7.0.1

      - name: Set variables from JSON
        id: json2vars
        uses: 7rikazhexde/json2vars-setter@v1.13.0
        with:
          json-file: .github/json2vars-setter/sample/matrix.json

  run_tests:
    needs: set_variables
    strategy:
      matrix:
        os: ${{ fromJson(needs.set_variables.outputs.os) }}
        python-version: ${{ fromJson(needs.set_variables.outputs.versions_python) }}
    runs-on: ${{ matrix.os }}
    steps:
      - name: Checkout repository
        uses: actions/checkout@v7.0.1
        with:
          fetch-depth: 0

      - name: Set up Python
        uses: actions/setup-python@v7.0.0
        with:
          python-version: ${{ matrix.python-version }}
      # Other steps

Components

The action consists of three main components that work together to provide a powerful, flexible solution:

1. JSON to Variables Parser: Core component that parses JSON and converts it to GitHub Actions outputs
2. Dynamic Matrix Updater: Updates your matrix configuration with the latest or stable language versions
3. Version Cache Manager: Manages cached version information to optimize API usage

Documentation

For detailed information, please check the Documentation Site.

The documentation includes:

• Getting Started guide
• Detailed feature explanations
• Usage examples
• Complete reference of all configuration options

License

This project is licensed under the MIT License - see the LICENSE file for details.