Fly.io ❤️ Bun

Summary

Fly.io is preparing support for Bun as Bun 1.0 approaches, expanding beyond its ongoing Node.js work because Bun aims for complete Node.js API compatibility. With flyctl 0.1.54 and @flydotio/dockerfile 0.3.3, users can launch and deploy Bun applications through fly launch and fly deploy if Bun 0.5.3 or later is installed and package.json includes an eligible start, module/type, or main configuration. The post says applications following Bun’s Quickstart and Fly’s hands-on walkthrough can be deployed, and provides a sample. Support is beta, with noted compatibility issues including bun install lacking --prune, unsupported throwIfNoEntry in fs.statSync, and readline-based programs failing to exit; shared Dockerfile generation means fixes for either runtime generally benefit both.

Takeaways

1. 1

   Bun deployment requires Bun 0.5.3 or later and a package.json with a start script entry, a module entry paired with module as the type, or a main entry.

2. 2

   The beta support encountered missing bun install --prune support, unsupported throwIfNoEntry in fs.statSync, and readline-based programs that never exit; global.prompt resolved the latter issue for @flydotio/dockerfile.

3. 3

   Bun and Node.js use the same Dockerfile generator, so fixes made for either runtime will generally benefit both.