How can I use Vite env variables in vite.config.js?

You can load the app level env variables and add them to the Node level env variables:

import { defineConfig, loadEnv } from 'vite';
import vue from '@vitejs/plugin-vue';


export default ({ mode }) => {
    process.env = {...process.env, ...loadEnv(mode, process.cwd())};

    // import.meta.env.VITE_NAME available here with: process.env.VITE_NAME
    // import.meta.env.VITE_PORT available here with: process.env.VITE_PORT

    return defineConfig({
        plugins: [vue()],

        server: {
            port: parseInt(process.env.VITE_PORT),
        },
    });
}