Custom domain names

[benallfree]

Allow custom domains

Frontend:

• Add cname to instances
• cname must be blank or globally unique
• cname must be a valid domain name (https://www.regextester.com/106386)
• create instructions that cname must resolve to <uuid>.pockethost.io along with a button to test manually
• A cname_status flag: verifying, ssl, active, and failed
• A cname_reason field capturing the latest failure message

Daemon updates:

• For all instances with verifying status, do a cname check to make sure it links to the correct subdomain. If it doesn't, set to failed with a cname_reason
• CERTBOT - set to ssl and issue new SSL cert and update nginx & refresh, or set to failed with a reason
• Once cname and certbot are done, set status to active
• Periodically check (cname_checked_at) to re-verify that cname resolves properly - every 5 minutes? update status and reason if failure
• Periodically renew certbot (every 90 days) (certbot_renewed_at), updating status and reason if failure

[benallfree]

Probably we should do this along with #42

[benallfree]

moved to roadmap

[benallfree]

Cloudflare supports custom hostnames https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/