🐛 BUG: Miniflare KV persistence not working in Wrangler2 --local mode

What version of Wrangler are you using?

0.0.24

What operating system are you using?

Mac OS (ARM64)

Describe the Bug

It seems as Wrangler2 uses Miniflare under the hood in --local mode, many Miniflare features should work, especially persistence around KV etc. But for some reason persistence doesn’t kick in when using

[miniflare]
kv_persist = true

in wrangler.toml. Also other kv_persist options don’t work, KV namespace are just empty on each change of a worker file. This really hurts productivity, I’m assuming this is unintended and should work?

Using typescript and modules, can provide a minimal reproduction case once this is confirmed as a bug.

[threepointone]

We have a fix in place, you can try it with wrangler@alpha. We will revisit it and make it better, but it should hopefully unblock it for you now. We will do a beta release soon too. Thank you for reporting!

[threepointone]

We’d only just started working on this, hence the experimental flag. What the flag does, is enable persistence for kv/durable_objects/cache in miniflare https://github.com/cloudflare/wrangler2/blob/ed4f2ef00f86374ac7d1ac6ff072d939c80b6c18/packages/wrangler/src/dev/local.tsx#L163-L170 This does persist to disk. However, we use a fresh temp directory where the actual worker is bundled, and that temp directory disappears when you close wrangler dev. Instead, we should be persisting to a path relative to the working directory, so that it sticks around in a known location (and let users like you decide what to do with the generated files). I’ll send a fix for this soon.

The workaround for now if you want to test persistence, is to use regular “remote” mode. But we’ll fix it very soon!