Files
windmill/debugger/README.md
Ruben Fiszel f8cbf15d86 refactor: change debugger port from 5679 to 3003
Updates the debugger service to use port 3003 instead of 5679 across
all configuration files, documentation, and code references. This aligns
the debugger with the other windmill-extra services which use ports
3001 (LSP) and 3002 (Multiplayer).

Changes:
- docker-compose.yml: Update port exposure and add DEBUGGER_PORT env
- docker/entrypoint-extra.sh: Change default port from 5679 to 3003
- debugger/dap_debug_service.ts: Update default port in code and docs
- debugger/README.md: Update port documentation
- debugger/test_debug_service.ts: Update test URLs
- docker/test_windmill_extra.ts: Update test configuration
- .github/workflows/publish_extra.yml: Update test container ports
- frontend/src/lib/components/debug/*: Update frontend examples and defaults

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-01-13 17:58:12 +00:00

3.8 KiB

Windmill Debug Module

A DAP (Debug Adapter Protocol) implementation for debugging Python and TypeScript/Bun scripts in Windmill's Monaco editor.

Overview

This module provides step-through debugging capabilities with breakpoints, variable inspection, and stack traces. It uses WebSocket communication between the Monaco editor frontend and language-specific debug backends.

Supported Languages

  • Python - Uses a bdb-based debugger via dap_websocket_server.py
  • TypeScript/Bun - Uses V8 Inspector Protocol via dap_websocket_server_bun.ts

Architecture

┌─────────────────────┐     WebSocket      ┌──────────────────────────┐
│  Monaco Editor      │◄──────────────────►│  DAP Debug Service       │
│  (dapClient.ts)     │    DAP Protocol    │  (dap_debug_service.ts)  │
└─────────────────────┘                    └──────────┬───────────────┘
                                                      │
                                           ┌──────────┴───────────┐
                                           │                      │
                                    ┌──────▼──────┐       ┌───────▼───────┐
                                    │   Python    │       │   Bun/TS      │
                                    │   Debugger  │       │   Debugger    │
                                    └─────────────┘       └───────────────┘

Files

File Description
dap_debug_service.ts Unified WebSocket server that routes to Python or Bun debuggers
dap_websocket_server.py Python debugger backend (bdb-based)
dap_websocket_server_bun.ts Bun/TypeScript debugger backend (V8 Inspector)
dapClient.ts Client-side DAP WebSocket client with Svelte store
MonacoDebugger.svelte Monaco editor integration component
DebugToolbar.svelte Debug control buttons (step, continue, etc.)
DebugPanel.svelte Variables and stack trace display panel
index.ts Module exports

Usage

Starting the Debug Service

bun run debug/dap_debug_service.ts

Options:

  • --port PORT - Server port (default: 3003)
  • --host HOST - Server host (default: 0.0.0.0)
  • --python-path PATH - Python binary path (default: python3)
  • --bun-path PATH - Bun binary path (default: bun)
  • --nsjail - Enable nsjail sandboxing for debugger processes
  • --nsjail-config PATH - Path to nsjail config file
  • --nsjail-path PATH - Path to nsjail binary (default: nsjail)

Endpoints

  • /python - Python debugging
  • /typescript - TypeScript/Bun debugging
  • /bun - Alias for /typescript

Environment Variables

Variable Description Default
DAP_PORT Server port 3003
DAP_HOST Server host 0.0.0.0
DAP_PYTHON_PATH Python binary path python3
DAP_BUN_PATH Bun binary path bun
DAP_NSJAIL_ENABLED Enable nsjail sandboxing false
DAP_NSJAIL_PATH nsjail binary path nsjail
DAP_NSJAIL_CONFIG nsjail config file path -

Frontend Integration

<script>
  import { MonacoDebugger } from './debug'
  let editor // Monaco editor instance
  let code = 'print("Hello")'
</script>

<MonacoDebugger {editor} {code} language="python3" />

Testing

# Test Python debugger
bun run debug/test_dap_server.py

# Test Bun debugger
bun run debug/test_dap_server_bun.ts

# Test unified service
bun run debug/test_debug_service.ts