Allow setting mode via environment variable

[rschamp]

Description

I am used to being able to configure my builds in CI via environment variables. E.g., if I have npm run build I would like to be able to use that same command, but have it behave differently based on the environment. Currently I can somewhat affect my build via NODE_ENV=production for a production build and NODE_ENV=development for a staging build. I would like to have the same control for the mode.

Suggested solution

Similarly to NODE_ENV we could have the VITE_MODE or MODE environment variable change the mode.

Alternative

In order to change import.meta.env.MODE, I need a separate command npm run build:staging, or I need to adjust the command I run like npm run build -- --mode staging. These workarounds make my CI config more complex than it could be.

Additional context

No response

Validations

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[sapphi-red]

If you can put "build": "vite --mode ${VITE_MODE:-production}" (for bash), then I think you can run npm run build/MODE=staging npm run build.

[rgrace-puck]

If you need to do this in a cross-platform way (e.g. for developer machines and CI builds), I used the package cross-replace to get the environment variable value.

Install:
npm install --save-dev cross-replace

package.json

"build": "cross-replace vite build --mode %VITE_MODE%"