process.env.NODE_ENV not set to production

[RobbinBaauw]

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• Use Vite >=2.0. (1.x is no longer supported)
• If the issue is related to 1.x -> 2.0 upgrade, read the Migration Guide first.

Describe the bug

Plugins don't have the process.env.NODE_ENV variable set to production when building for production.

I came across this when my tailwindcss build was suddenly huge, since the purge plugin relies on process.env.NODE_ENV being set to production, whereas it was development since Vite 2.

Reproduction

1. Clone https://github.com/RobbinBaauw/vite-process-repro
2. yarn && yarn build
3. Note the development in the logs

The only change I made w.r.t. the default template is adding a plugin:
https://github.com/RobbinBaauw/vite-process-repro/blob/1ef30c9230c79f43e7b69f2e95f6294e1aab9e26/vite.config.js#L6-L14

You'll also see logs of undefined, I'm not sure if that's an issue as well.

System Info

• vite version: 2.0.0-beta.12
• Operating System: Pop!_OS
• Node version: node 12.18.1
• Package manager (npm/yarn/pnpm) and version: yarn 1.22.4