Firebase Hosting

"records": { "A": ["199.36.158.100"] }

Firebase's Quick Setup flow points a custom subdomain at this IP for every project, the same address it shows in the console. Firebase can change it, so if the console shows a different address when you set this up, use that one instead.

Two ways to apply this. The quickest is runs-at.dev/manage: sign in, pick the record type, paste the value, save. It writes the same commit to the registry and DNS follows within seconds. The steps below do it by pull request instead, which is what you want if you would rather review the change first. Either way handles subdomains entries.

1. In the Firebase console: Hosting → Add custom domain → you.runs-at.dev → Quick Setup. Note the A record value it shows you.
2. Fork the registry and edit domains/you.json to the record above, using that value.
3. Open a pull request. Once merged, the A record is synced to DNS automatically.

The Hosting console shows you.runs-at.dev as connected once Firebase has confirmed the A record and issued a certificate, which can take a few hours. Visiting https://you.runs-at.dev should then serve the site.