title: Read file with firebase function
body: <p>I've got a Firebase Function and want to read a html file, stored in a subfolder.</p>
  <pre><code>── functions
      ├── src
      |   ├── index.ts // Here is the function
      |   ├── html
      |   |   ├── template.html // the file I want to read
  </code></pre>
  <p>I tried to read the file via  <code>const html = fs.readFileSync('./html/template.html');</code> but it always tells me</p>
  <blockquote>
  <p>Error: ENOENT: no such file or directory, open './html/template.html'
  at Object.openSync</p>
  </blockquote>
  <p>I worked trough almost every question on stackoverflow concerning this topic but nothing worked for me. I also tried placing the file in the same folder as the function but it always gives me the error.</p>
  <p>Do I need to install some package or import the file in some way to access it?</p>