Desktop App

The desktop shell (src-tauri/, crate otel-viewer-tauri) wraps the entire stack — OTLP receiver, DuckDB, REST router, web UI — in one native window via Tauri 2. No external services; the collector runs in-process.

How the window is served: otelview://

The webview does not load http://127.0.0.1:6666. Instead it uses the custom otelview:// URI scheme (https://otelview.localhost/ on Windows), registered with register_asynchronous_uri_scheme_protocol in src-tauri/src/lib.rs. Scheme requests are answered by calling the axum router in-process (otel_viewer::run_with_db shares the Db handle with the TCP server).

Why: on macOS 26 (Tahoe), WKWebView silently refuses navigations to plain http://127.0.0.1:<port> — Local Network privacy hardening. No error, no TCP connection, permanent about:blank (a white window). App Transport Security exceptions in Info.plist do not help. The custom scheme makes the webview’s traffic a pure in-process IPC call, which no ATS/Local-Network policy can block.

The router still binds a real TCP port for external use — open http://127.0.0.1:6666 in any browser, or curl the API — and the OTLP/gRPC receiver binds 127.0.0.1:4317 (with fallbacks) for exporters.

Runtime facts

• Persistent DuckDB at
  • macOS: ~/Library/Application Support/com.otelviewer.desktop/otel-viewer.duckdb
  • Windows: %APPDATA%\com.otelviewer.desktop\otel-viewer.duckdb
• Demo telemetry is seeded when the database is empty
• Single instance: launching a second copy focuses the first
• All listeners bind 127.0.0.1 only

Build

pnpm install          # tauri CLI (root package.json)
pnpm -C web install   # web UI dependencies
pnpm tauri build

Outputs:

• macOS: src-tauri/target/release/bundle/macos/otel-viewer.app and the .dmg (use --target universal-apple-darwin for a universal binary)
• Windows: NSIS installer under src-tauri/target/release/bundle/nsis/

Prerequisites and troubleshooting are in src-tauri/README.md.