FastEdge VSCode Extension

A VS Code extension for building, running, and debugging Gcore FastEdge applications — with a Postman-like interface for crafting requests and inspecting responses.

Supports both HTTP apps and CDN apps across three languages:

     

How it works

The extension compiles your code into a WASM binary using language-specific build tools, then serves it locally using a bundled debugger — no external tools required.

A webview panel opens inside VS Code where you can:

• Build requests (URL, method, headers, body)
• Send them to your running app
• Inspect the response (status, headers, body)
• Load and save test configurations

Each app gets its own isolated server instance on a port in the range 5179–5188, so you can debug multiple apps in the same workspace simultaneously.

Prerequisites

You need the build tools for your chosen language installed:

Rust (HTTP or CDN apps):

rustup target add wasm32-wasip1

JavaScript (HTTP apps):

npm install --save-dev @gcoredev/fastedge-sdk-js

AssemblyScript (CDN apps):

npm install --save-dev assemblyscript @assemblyscript/wasi-shim @gcoredev/proxy-wasm-sdk-as

More detail can be found in the SDK documentation linked above.

Installing the extension

This extension can be installed from the Visual Studio Marketplace: FastEdge Launcher

It is also possible to install from source: Releases

Running your first application

Press F5 in VS Code (or Command Palette → Debug: Start Debug).

When running for the first time, you'll need a .vscode/launch.json. The easiest way is to let the extension create one:

Command Palette (Ctrl+Shift+P) → FastEdge: Initialize workspace (create launch.json)

Example launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "FastEdge App Runner: Launch",
      "type": "fastedge",
      "request": "launch",
      "entrypoint": "file"
    }
  ]
}

The entrypoint field controls how the build finds your source code:

These are the only configuration values read from launch.json. Runtime arguments (env vars, headers, etc.) are configured separately — see Runtime Configuration below.

Language detection

The extension auto-detects your project language:

Commands

Available from the Command Palette (Ctrl+Shift+P):

Explorer context menu

Right-click actions in the file explorer:

Runtime Configuration

Environment variables, secrets, request headers, and response headers are configured through test configuration files — not launch.json.

Primary: fastedge-config.test.json

The debugger UI provides built-in controls to set environment variables, secrets, and headers. These are saved to and loaded from fastedge-config.test.json in your app root, using native file dialogs.

Alternative: dotenv files

You can also provide runtime arguments via .env files that the extension auto-discovers from your app root directory.

Please be aware that if you are adding sensitive information to these files, they should be added to your .gitignore:

# VSCode workspace
.vscode/

# dotenv files
.env
.env.*

# Build artifacts
.fastedge-debug/

For more information on how the extension locates and uses dotenv files, see DOTENV.md.

Settings

To view the bundled debugger version:

1. Open Settings (Ctrl+, or Cmd+,)
2. Search for "FastEdge"