Does Google Domains support CNAME-like functionality at the zone apex?
The full list of records supported by Google Domains can be found at:
There is no 'ALIAS' or 'ANAME' or any other similar pseudo-CNAME supported.
Please note that the type of record mentioned by the Heroku documentation is not an actual CNAME, but rather an A record that is auto-updated to match some arbitrary external A record. Amazon Route 53, as well as several other DNS providers offer this, and call it various things - some call it ALIAS or ANAME etc - but it is not an actual RR type.
Google domains does support a thing called "synthetic records", however AFAIK it would not help you with Heroku.
No, but you can have Google Domains forward your root domain to your www CNAME.
First create a CNAME in the Custom Records section pointing
Then in the Synthetic Records section, choose
Subdomain forward, enter
@ in the
subdomain field and
www.yourdomain.com in the
Destination URL field.
Save those and you're done.
Cloudflare ended up working for me (free plan), check out http://www.higherorderheroku.com/articles/cloudflare-dns-heroku/. Their onboarding is great, they walk you through changing your nameserver and automatically apply some magic ("CNAME flattening") when you set a CNAME record for the root domain.