This article is for hosting your static website into Google App Engine. This article provides an app.yaml file so you can host your static website into Google App Engine. Before do anything make your website’s folder structure like that (see below image). So put all the static files inside assets folder (css, js, images, fonts) and all HTML files in project’s root directory. Inside assets folder css, js, img, and fonts are sperate folders for holding separate files (ex. css file stylesheets, img for images)
Then copy-paste this snipped in your YAML file. And then deploy (gcloud app deploy) your application.
You can also make your project structure your own way, then you have to change YAML content based on your changes. So that means need to change YAML information according to your project’s structure.