How to build with rolldown-vite?

[alexbjorlig]

We have a large Sveltekit application, so it would be nice with faster builds.

Currently, it takes around 2 minutes and 45 seconds to build.

Now I'm trying to test out rolldown-vite, by adding this to my pacakge.json:

"devDependencies": {
  "vite": "npm:rolldown-vite@latest"
},  
"overrides": {
        "vite": "npm:rolldown-vite@latest"
    },

But I don't think it's actually working, because buildtime is not improved.

Is there anything else that must be configured to use vite rolldown?

[realfakenerd]

I think you should see the pr that added support for Rolldown #13747 and the article of July, it seems you also need to reinstall your dependencies as stated in vite docs after adding the override.

[alexbjorlig]

Hi @realfakenerd - thanks for the suggestions.

I did try to reinstall dependencies, but no help.

[realfakenerd]

Well, at the Svelte July article, it says that builds could be bigger, but maybe it could be longer instead since it is a work in progress

[alexbjorlig]

@eltigerchino is there something we have to configure to try rolldown, or is it not supported yet?

[teemingc]

Hi Alex. It should be as simple as https://vite.dev/guide/rolldown.html#how-to-try-rolldown like what you've done already. However, it also helps if you have the latest versions of SvelteKit and vite-plugin-svelte which enable support for Rolldown. At the very least, you should have @sveltejs/kit@2.23.0 and vite-plugin-svelte@6.0.0

See #13738 for remaining issues

[alexbjorlig]

Thanks for the quick answer. @eltigerchino do you know if there is a way to tell in the build logs (or other ways) that rolldown is being used? I was hoping for reduced build time 🫣

[teemingc]

Yes, vite-plugin-svelte should be printing out that rolldown usage is experimental

[alexbjorlig]

Ok I had to delete node_modules and package-lock.json.
It now fails with:

rolldown-vite v7.1.2 building SSR bundle for production...

thread '<unnamed>' panicked at crates/rolldown_binding/src/utils/normalize_binding_options.rs:524:37:
Should convert to builtin plugin: Alias 
 StringExpected, Failed to convert JavaScript value `Boolean false ` into rust type `String` on BindingAliasPluginAlias.replacement on BindingAliasPluginConfig.entries
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5, aborting

But well, it's experimental 😎

[teemingc]

I highly recommend trying to reproduce and creating an issue at https://github.com/vitejs/rolldown-vite
They are very responsive!