trellis

Polyglot Tools Example (Trellis Process Adapter)

This example demonstrates how to integrate scripts written in Python, Node.js, and PowerShell with Trellis.

The Contract (Unix Style)

Trellis adheres to a simple, universal contract for external tools, inspired by the Unix philosophy:

1. Input: Arguments are passed as Environment Variables, prefixed with TRELLIS_ARG_.
   • Example: args: { name: "Bob" } becomes TRELLIS_ARG_NAME="Bob".
   • This avoids CLI flag parsing complexity and injection risks.
2. Output: The tool should print a JSON Object to Stdout.
   • Trellis automatically detects JSON output and parses it into a structural object.
3. Error: To signal failure, exit with a non-zero status code.
   • Optional: Print error details to Stderr, which Trellis captures for debugging.

Directory Structure

• tools.yaml: Registers the scripts as named tools (greet_py, greet_js, greet_ps).
• py-tool.py: Python implementation (using os.environ and print(json.dumps)).
• js-tool.js: Node.js implementation (using process.env and console.log).
• ps-tool.ps1: PowerShell implementation (using $env: and ConvertTo-Json).
• start.md: The entry point flow that orchestrates the execution.

How to Run

Navigate to this directory and run Trellis:

# Run interactively
go run ../../cmd/trellis run .

# Run headless (for testing)
go run ../../cmd/trellis run . --headless

Tips for Windows Users

• Ensure python, node, and pwsh (or powershell) are in your PATH.
• If using tools.yaml, the command field must match an executable on your system.

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