Miniflare v3 now uses workerd, the open-source Cloudflare Workers runtime. This is the same runtime that's deployed on Cloudflare’s network, giving bug-for-bug compatibility and practically eliminating behavior mismatches. Refer to the Miniflare v3 and Wrangler v3 announcements for more information.
Missing Features
Several features from Miniflare v2 are not supported in Miniflare v3's initial release. However, they are on the roadmap, and will be added back soon:
- Step-through debugging
- Automatically triggering scheduled events via CRON schedules, or manually triggering them via
/.mf/scheduledor/cdn-cgi/mf/scheduled(manually triggering events is supported via the--test-scheduledWrangler flag and visiting/__scheduled) - Starting an HTTPS server
- Mocking outbound
fetch()requests - The
get{Bindings,KVNamespace,R2Bucket,Caches,DurableObjectNamespace}()methods
CLI Changes
Miniflare v3 no longer includes a standalone CLI. To get the same functionality, you will need to switch over to Wrangler. Wrangler v3 uses Miniflare v3 by default. To start a local development server, run:
$ npx wrangler@3 devIf there are features from the Miniflare CLI you would like to see in Wrangler, please open an issue on GitHub.
API Changes
We have tried to keep Miniflare v3's API close to Miniflare v2 where possible, but many options and methods have been removed or changed with the switch to the open-source workerd runtime. See the 📚 GitHub README for the new API docs, and the ⬆️ Migration Guide for the full list of removals and changes.