.eleventy.js

module.exports = function (config) {
  config.addPlugin(EleventyServerlessBundlerPlugin, {
    name: 'possum', // The serverless function name from your permalink object
    functionsDir: './functions/',
  });

  return {
    dir: {
      input: 'src/site/content/', // we use a string path with the forward slash since windows doesn't like the paths generated from path.join
      output: 'dist',
      data: '../_data',
      includes: '../_includes',
    },
    templateFormats: ['njk', 'md'],
    htmlTemplateEngine: 'njk',
    markdownTemplateEngine: 'njk',
    // Because eleventy's passthroughFileCopy does not work with permalinks
    // we need to manually copy assets ourselves using gulp.
    // https://github.com/11ty/eleventy/issues/379
    passthroughFileCopy: false,
  };
};

firebase.json

{
  "hosting": {
    "public": "dist",
    "rewrites": [{
      "source": "/possum",
      "function": "possum"
    }]
  },
  "emulators": {
    "hosting": {
      "port": 8080
    }
  }
}

index.js

// /functions/index.js

const possum = require('./possum');

exports.possum = possum.possum;

index.mjs

// /functions/possum/index.js

const functions = require('firebase-functions');
const {EleventyServerless} = require('@11ty/eleventy');

// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions

exports.possum = functions.https.onRequest(async (request, response) => {
  functions.logger.info('Hello logs!', {structuredData: true});
  // return response.send(`You requested path: ${request.path}`);

  const elev = new EleventyServerless('serverless', {
    path: request.path, // required, the URL path
  });

  try {
    // returns the HTML for the Eleventy template that matches to the URL
    const html = await elev.render();
    return response.send(html);
  } catch (e) {
    return response.status(500).send(JSON.stringify({error: e.message}));
  }
});

index.njk

---
layout: default
title: About
permalink:
  possum: /about/
---
It's our about page!