I have a GAE app set up to use a custom domain, let's call it mycustomdomain. This naked domain is working fine over HTTP and HTTPS. I also have a service called api, it can be accessed successfully by going to http://api.mycustomdomain.com (custom domain convention).
However, I can't access the api service over HTTPS. I uploaded a SSL for mycustomdomain.com, but I got an error (site can't be reached) for trying to accessing the api service over HTTPS. My question is do I need to purchase the wildcard.mycustomdomain.com SSL in order to access the api service over HTTPS? I don't have much experience dealing with SSL certs and GAE custom domain, so any help would be greatly appreciated. Thank you!
Edit: updated information for GCP Console configurations. My app setup in the Console contains the following: Services: default, api Custom domain setup: mycustomdomain.com SSL uploaded: ultrahdlivewallpaper.com (NOT the wildcard version), api.ultrahdlivewallpaper.com (unable to be enabled for custom domain, none matching)
More detail: The problem is when I map both ultrahdlivewallpapers.com and api.ultrahdlivewallpapers.com, they are both mapped to the default service. I want api. to point to the API service. If I only map ultrahdlivewallpapers.com, that allows me to access api service at the api subdomain, but then the api SSL can't be applied to api. subdomain because it's not listed as a subdomain.
07/24/17 Update: I believe this is a limitation with the App Engine Settings after trying out several scenarios via GAE Console. We have a custom domain set up for ultrahdlivewallpapers.com and enabled the SSL cert for this domain. The domain is pointing to the default service. We have a second service set up called API. Google's routing rules for any service set up is via HTTP:// service-id.custom-domain, which in our case is api.ultrahdlivewallpapers.com. However, when I upload the SSL for the api subdomain, Console couldn't find matching domains because the api subdomain is not specified via the Console. Now if I set up api.ultrahdlivewallpapers.com as a custom domain, I'm able to enable the SSL for api subdomain. Problem then becomes api subdomain is now pointing to the default service instead of the api service. If I remove the api mapping, I'm able to browse to the api service again, but no HTTPS! I don't believe there is a way to get this set up correctly without a wildcard SSL enabled for all subdomains. Please let me know if I'm missing anything. I have tried everything I can think of via the Console. Thanks.