Github Pages env var for SvelteKit (WIP)

build-deploy.yaml

# .github/workflows/build-deploy.yaml
name: Build and Deploy
on:
  push:
    branches:
      - main
    # Sustainability: Don't trigger build for updated README
    paths-ignore:
      - '**/README.md'
    # Allows you to run this workflow manually from the Actions tab.
    # workflow_dispatch:
permissions:
  contents: write
jobs:
  build-and-deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout 🛎️
        uses: actions/checkout@v3
      - name: Use Node LTS
        uses: actions/setup-node@v3
        with:
          node-version: '18' # lts

      # This build runs with path prefix for github pages (hosted on subdirectory),
      # for example https://<USER>.github.io/<REPO-NAME>/
      # See: https://kit.svelte.dev/docs/adapter-static#github-pages
      
      - name: Install and Build for Github Pages 🔧
        run: |
          npm ci
          npm run build
        env:
          PATHS_BASE: '/${{ github.event.repository.name }}'
          # Not needed currently: 
          #BASE_URL: 'https://${{ github.event.repository.owner.name }}.github.io/'
      - name: Archive production artifacts
        uses: actions/upload-artifact@v3
        with:
          name: build-folder
          path: |
            build
      - name: Deploy to Github Pages 🚀
        uses: JamesIves/github-pages-deploy-action@v4
        with:
          branch: gh-pages
          folder: build #the output folder

svelte.config.js

import adapter from '@sveltejs/adapter-static';
import sveltePreprocess from 'svelte-preprocess';

//import { env } from '$env/dynamic/private';

let pathsBase = '';
// https://stackoverflow.com/posts/67978668/revisions
if(process.env['PATHS_BASE'] != undefined){
	console.log('paths.base was set via node env variable',process.env.PATHS_BASE);
	pathsBase = process.env.PATHS_BASE;
}else{
	console.log('No paths.base set, defaults to \'\'');
}

/** @type {import('@sveltejs/kit').Config} */
const config = {
	preprocess: sveltePreprocess(),
	kit: {
		// https://stackoverflow.com/a/72733222
		adapter: adapter({
			pages: 'build',
			assets: 'build',
			fallback: null,
			precompress: false
		}),
		paths: {
			base: pathsBase
			// e.g. for github pages -> repository name: '/repository-name'
			//https://kit.svelte.dev/docs/adapter-static#github-pages
		}
	}
};

export default config;