$ show balena-io/etcher
balenaEtcher is a cross-platform Electron desktop application for flashing OS images to SD cards, USB drives, and similar removable media. In production it provides a wizard-style UI where users select a source image (local file, URL, or an existing drive), choose a target drive, and flash with pre-write safety checks and post-write verification. The architecture is a three-process Electron app: the main process manages windows, menus, auto-updates, and IPC; the renderer runs a React/Redux UI built with TypeScript and styled-components; and a privileged Node.js sidecar process, packaged separately via pkg, performs drive scanning, image metadata extraction, and the actual flashing over a WebSocket connection. Core flashing operations are delegated to etcher-sdk, while OS-specific privilege elevation is handled through sudo on Linux/macOS and UAC on Windows.
The LLM identified 4 files worth highlighting for reuse:
Encapsulates safety-critical drive eligibility rules (size, system/locked drives, source/target identity) as pure predicate functions with typed errors. Used by the UI and sidecar, and reusable in any drive-management or flashing tool that needs to prevent destructive writes.
Defines serializable, human-readable error codes with user-facing titles and descriptions, allowing error context to survive IPC boundaries between the renderer, main process, and sidecar. The pattern of converting low-level failures into stable public error contracts is reusable across distributed or multi-process applications.
Per-platform elevation helper for macOS (with Linux and Windows counterparts) that isolates OS-specific admin escalation behind a common interface. This demonstrates how to safely structure privilege elevation in an Electron or Node.js tool and can be extracted for other applications needing guarded administrative operations.
React wrapper around Electron's webview that restricts navigation and popup behavior while rendering trusted external content such as success banners. It demonstrates a reusable secure-embedding pattern for Electron apps that need to display third-party web content without exposing Node integration or allowing arbitrary navigation.