You can configure your domain to host an App Engine app through the Google Cloud Console and Google Domains:
- Go to the Cloud Console and select your project or application.
- In the left menu , go to App Engine Settings .
- Click the Custom Domains tab.
- Click Add a custom domain.
- If your domain is already verified, the domain opens in the Select the domain you want to use section. Select the domain from the drop-down menu and click Continue.
- If the domain you want to use is not listed:
- Select Verify a new domain from the menu .
- Enter your domain name (such as “example.com”).
- Click Verify.
- Enter information in the Webmaster Central window that opens. For help with using Webmaster Central, go to Webmaster Central help.
- Return to the Add a new custom domain page in the Google Cloud Console.
- In the Point your domain to [project-ID] section, specify the domain and subdomains that you want to map. When you've added all the mappings you want, click Save mappings.
- Click Continue to find your domain's DNS records..
- In the next steps, you’ll input this information into your Google Domains account.
- Return to Google Domains.
- Select your domain.
- Click Menu.
- Click DNS.
- Scroll to custom records and create the CNAME record mapping for your app. For example, if your subdomain is “app” then your record will appear as the following:
app.mydomain.com CNAME 1H ghs.googlehosted.com.
For more information, go to Mapping custom domains.