How to add domain to Firebase and subdomain to GCP in Cloudflare

Question

I have the example.com domain in Cloudflare connected to an application hosted in Firebase and a second application that should use the subdomain api.example.com hosted in GAE, but when I try to connect the subdomain in GAE I got the following error:

The CAA domain registration does not allow you to activate the certificate. Composed of DNS settings.

The domain works perfectly with Firebase, but the subdomain does not work with GAE. I have added the corresponding records in each case, but the subdomain still doesn't work, which only shows me this screen:

Cloudflare screen

My question is if I have a domain on one platform and a subdomain on another. Well, I actually know that this can be done, because once I set up the subdomain in Heroku and domain in Firebase, but I have not managed to do it with GAE and Firebase

Answer 1

Following are the access the required setup.

Settings:

|------------|-----------------|-----------------|------------|
|    Type    |       Name      |     Content     |     TTL    |
|------------|-----------------|-----------------|------------|
|     A      | api.example.com |      HostIP     |     Auto   |
|------------|-----------------|-----------------|------------|
|   CNAME    |       www       | api.example.com |    Auto    |
|------------|-----------------|-----------------|------------|