A Globally Synchronized Digital Light Switch
World Wide Bulb (WWB) is a real-time web application where visitors from anywhere on Earth can toggle a shared digital lightbulb. Every light switch toggle is synchronized instantly across all connected clients via WebSockets.
While simple in concept, the project is engineered as an overkill, production-grade application featuring rate limiting, privacy-preserving IP hashing, real-time viewer counting, infinite-scroll history tracking, and single-binary deployment.
Technical Architecture & Key Features
High-Performance Go Backend
- Real-Time WebSockets: Uses
gin-gonicandgorilla/websocketto handle concurrent WebSocket connections with low latency. - Type-Safe Database Layer with
sqlc: SQLite database interactions are powered bysqlc, generating type-safe, compiler-proven Go code directly from raw SQL queries & schema migrations. - Pure Go Driver & Zero CGO: Uses
modernc.org/sqlite(a pure Go SQLite driver), removing the need for a C compiler and making cross-compilation effortless. - Privacy & Anti-Abuse: Prevents spamming via a 10-second per-user cooldown. User identifiers are computed using salted SHA-256 hashes of the IP address and session cookie, ensuring zero Personally Identifiable Information (PII) is stored.
Modern Svelte 5 Frontend
- Reactive Lightbulb Component: Interactive vector SVG bulb with CSS glow filters and smooth state transition animations.
- Infinite-Scrolling History: Lazy-loaded toggle log showcasing historical state changes, user timestamps, and toggle reasons.
- Real-Time Active Viewer Counter: Live badge showing the exact number of active WebSocket connections watching the bulb simultaneously, accompanied by rotating status texts.
- Profanity Filtering: Integrated
go-awaylibrary to sanitize toggle reason submissions and strip offensive text/leetspeak.
Single Binary & Containerized Deployment
- Embedded Frontend (
embed.FS): The static SvelteKit frontend is compiled and embedded directly into the Go binary. The entire application runs as a single executable (bin/wwb). - Lightweight Docker Image: Built via multi-stage Docker builds on top of
alpine, resulting in a tiny 20MB container image with minimal resource overhead. - Developer Workflow & Automation: Uses
justfor task orchestration,lefthookfor git pre-commit hooks, and GitHub Workflows for automated CI testing and single-binary release builds.