How to use Google App Engine with my own naked domain (not subdomain)?

[Update April 2016] This answer is now outdated, custom naked domain mapping is supported, see Lawrence Mok's answer.

I have figured it out!

First off: it is impossible to link something like mydomain.example with your appspot app. This is considered a naked domain, which is not supported by Google App Engine (anymore). Strictly speaking, the answer to my question has to be "impossible". Read on...

All you can do is add subdomains pointing to your app, e.g myappid.mydomain.example. The key to get your top level domain linked to your app is to realize that www is a subdomain like any other!

myappid.mydomain.example is treated exactly the same as www.mydomain.example!

Here are the steps:

1. Go to appengine.google.com, open your app
2. Administration > Versions > Add Domain... (your domain has to be linked to your Google Apps account, follow the steps to do that including the domain verification.)
3. Go to www.google.com/a/yourdomain.example
4. Dashboard > your app should be listed here. Click on it.
5. myappid settings page > Web address > Add new URL
6. Simply enter www and click Add
7. Using your domain hosting provider's web interface, add a CNAME for www for your domain and point to ghs.googlehosted.com

Now you have www.mydomain.example linked to your app.

I wished this would have been more obvious in the documentation.

[Update April 2016] This answer is now outdated, custom naked domain mapping is supported, see Lawrence Mok's answer.

See http://www.google.com/support/a/bin/answer.py?hl=en&answer=91077 for the details. Once you have signed up for Google Apps for Your Domain:

# Sign in to the Google App Engine admin console.
# Go to Administration > Versions
# Click the 'Add Domain...' button under Domain Setup.
# Enter your domain name in the 'Domain Name:' field
# Click 'Add Domain'. You will be directed to the Google Apps administrator console to complete the process.
# Log in to the Google Apps control panel with your administrator account.
# Accept the terms and specify the access URL you'd like to provide for your application.
# Click 'Accept

You can't use a naked domain, though, such as whatever.example (but www.whatever.example does work), because:

Due to recent changes, Google App Engine no longer supports mapping your app to a naked domain. If your domain registrar supports URL redirects, you can redirect from http://yourdomain.example to your app, which can be served from domains like http://www.yourdomain.example or http://appid.yourdomain.example.

as specified at http://www.google.com/support/a/bin/answer.py?answer=91080

If like me you have seen this message while trying to add 'www' as a subdomain inorder to get your own domain working:

'Already used, please remove previous mapping first . '

The above process mentioned in other answers has changed slightly if you are using Google Apps for your domain.

You must now do this as well:

Google Apps -> Service Settings -> Sites. Click 'Web address mapping' and remove the 'www' mapping which has been added by default to Sites.

Then you can add the 'www' subdomain for your App engine app

see this link:

http://groups.google.com/group/google-appengine/web/deleting-existing-www-mapping-from-google-apps

Google does not provide an IP for us to set A record. If it would we could use naked domains.

There is another option, by setting A record to foreign web server's IP and that server could make an HTTP redirect from e.g domain.example to www.domain.example (check out GiDNS)

For App Engine in 2019, googles has made it easier to set up a custom domain.

1. Google App Engine -> Settings -> Custom Domains

2. Verify your domain

3. Select Your Domain Name Registra

Reminder: Use TXT Record with the value Google provides without a existing CNAME record, otherwise TXT Record will be override

4. Follow the steps on the page, which includes the configuration of your subdomain, CNAME Record, A Record, AAAA Record, and you'll be good to go.

Just managed to sort this finally after hours. The www subdomain was pointing to Sites, but the front end wasn't showing me that.

After taking the plunge and setting the CNAME to gwh.google.com, and enabling / disabling Sites a couple of times (see the comment from Rodrigo Moraes on http://groups.google.com/group/google-appengine/web/deleting-existing-www-mapping-from-google-apps) I was able to set the Sites address to use the www subdomain.

I was then able to change it away from using the www subdomain, at which point the appengine app allowed me to specify the www subdomain.

That is one dirty fix - basically turning on and off Sites until it works!

You can create a custom domain (including naked domain) for your App Engine and you can also set up self managed SSL certificates there.

To use a custom domain, map the domain to your app, then update your DNS records. You can map a naked domain, such as example.com or a subdomain, such as subdomain.example.com. You can also use wildcards to map subdomains.

The steps to map custom domain to your application are following -

1. In Console,go to the Application settings tab of the App Engine Settings page -->If you need to enable G Suite authentication then click Edit to modify the Google Accounts API Referrer-->In the Google Authentication drop-down menu, select G Suite domain, then add your domain such as example.com in the empty field.

2. Go to the Custom Domains tab of the App Engine Settings page--> Click on add custom Domain-->If your Domain is already verified then select it from the drop down menu-->click Continue.

If you haven't verified your domain yet, follow the steps below:

 a) Select Verify a new domain from the drop-down menu.

 b) Enter your naked domain name (such as "example.com") and click Verify.   
          
 c)  Enter information in the Webmaster Central window that appears. 

 d) After you complete the steps in Webmaster Central, return to the Add a new    
 custom domain page in the Google Cloud Console.

3. In the Point your domain to (project-ID) section, specify the domain and subdomains that you want to map.We recommend mapping the naked domain and the www subdomain-->click Save mapping.

4. Sign in to your domain registrar web site and update your DNS records.

Please refer to the following link for detailed description of required steps -

https://cloud.google.com/appengine/docs/standard/python/mapping-custom-domains