We operate a domain marketplace that has hundreds of thousands of domains. Each server that provides for sale landers handles about 10,000 domains.
We would like to generate HTTPS pages for each domain instead of just HTTP but this could be challenging with let's encrypt and the query volumes offered.
We are basically interested in having SSL landing pages (for sale landers) for 10,000 domains+ and then obviously we'd want to renew them.
Does LetsEncrypt offer any type of a batch/bulk mode for certificate generation?
I know many registrars and hosting providers use LetsEncrypt for coming soon landers and parking pages so I'm curious if anyone has a good solution.
There are rate limits to be aware of, and it may be that your operation is big enough to request some overrides for some of them. But 10,000 domains isn't all that much on Let's Encrypt's scale, the default rate limit of 300 orders per 3 hours per account would let you get 10,000 in under a week just on one account, and you may be splitting your load across multiple accounts anyway.
I think what you're looking for isn't really on the Let's Encrypt side, but you're trying to ask about what ACME client would work best for you. And to answer that, I think we'd need more information on your infrastructure, and I don't know if there are many people that hang out here with experience working on that scale. (There are probably some, but I'm not among them.) You may be able to just use something like Caddy which requests certificates as needed on-demand, which might be easiest if the domains you're using regularly change.
For what it's worth, you can do CSV import of (http domain validated) domains with https://certifytheweb.com but that would currently require hosting on Windows (or at least acquiring the certs on Windows). I know at least one user is managing 22K certs on one instance.
I second the suggestion of just using Caddy though, seems like that would be a pretty easy solution.