问题
For my personal site, I have a firebase project (using firebase hosting) which is alloted to my apex domain (http://exmaple.com), and I have another firebase project, which I want to allot to a subdomain of the same apex domain (http://subdomain.example.com), but firebase doesn't allow me to do that, any workarounds?
回答1:
"This is currently a limitation of how custom domains work on Firebase Hosting. We're exploring ways to improve and make it possible to reuse the same apex domain across multiple sites, but we don't yet have anything concrete to announce at this time." - Michael Bleigh
回答2:
You can now add multiple domains to a single Firebase Hosting site. Domains can either serve site content or redirect to another domain (editable at any time). In addition, you can now use subdomains of the same registered domain on different projects, such as example.com on one project and blog.example.com on another. Visit your hosting admin page to configure them.
来源：https://stackoverflow.com/questions/38168120/use-apex-domain-and-subdomain-for-different-firebase-projects