Seems like the domain cloudapp.net is blacklisted. Could you tell me why it is blacklisted and if it will be supported in future?
I’m nothing to do with LE, my understanding is though …
Domains are blacklist is to protect against mis-issuance for high-risk domains (those which are more likely to be maliciously targeted for mis-issuance), hence LE don’t issue certificates for blacklisted domains.
If you are the owner of cloudapp.net, and feel that your domain is not high-risk, you can request that it be removed.
Personally, I’d just use my own domain name, that I control, it removes you from all the issues.
It’s the domain Azure uses for VMs.
Yes, I understand ( hence my assumption above that you were just wanting to use a subdomain of cloudapp.net). As I said above, you will need to talk to Azure ( cloudapp.net) since you don’t own the domain, you need to talk to those who do.
If you read Configuring SSL for an application in Azure they state;
You cannot obtain an SSL certificate from a certificate authority (CA) for the cloudapp.net domain.
You must acquire a custom domain name to use
It’s a limitation they have placed, not LE, so you need to either talk to them or ( as suggested above) get your own domain name.
We’ve applied many certs to custom domains mapped to cloudapp.net domains, which is fully supported in Azure. There is no reason you couldn’t do the same thing with Let’s Encrypt.