Getting config from node-config into Sapper as `process.env.variableName`

default.js

// config/default.js

module.exports = {
  myConfigVariable: 'It Works!'
}

package.json

{
  ...
  "scripts": {
    "dev": "NODE_CONFIG_ENV=${NODE_ENV} PORT=1234 sapper dev",
    "build": "NODE_CONFIG_ENV=${NODE_ENV} sapper build --legacy",
    ...
  },
  "devDependencies": {
    "config": "^3.1.0",
    "rollup-plugin-replace": "^2.0.0",
    ...
}

rollup.config.js

import replace from 'rollup-plugin-replace'
...
import conf from 'config'

...

const appConfig = Object.keys(conf).reduce((acc, n) => {
	acc[`process.env.${n}`] = JSON.stringify(conf[n])
	return acc
}, {})

export default {
	client: {
		...
		plugins: [
			replace({
				'process.browser': true,
				'process.env.NODE_ENV': JSON.stringify(mode),
				// Don't do this if your config contains senstive secrets - filter it.
				...appConfig
			}),
      ...
	},

	server: {
		...
		plugins: [
			replace({
				'process.browser': false,
				'process.env.NODE_ENV': JSON.stringify(mode),
				...appConfig
			}),
     ...
	},
  
  ...
}

SomeComponent.svelte

<h1>
  {process.env.myConfigVariable}
</h1>