I have a platform where my customers can use their own domain. But I am not sure of an easy (automated) way of doing this using LetsEncrypt.
There was a post awhile back that explained how Etsy does it (https://codeascraft.com/2017/01/31/how-etsy-manages-https-an...)
But it was wwaayy too much for a small startup like me.
I can think of a manual way of course.
See
https://letsencrypt.org/docs/integration-guide/
There are a lot of clients, several dozen of them already. There isn't necessarily a client that's specifically oriented toward provider integration, but one of the lightweight clients like acme.sh might be a good fit because it will work well with external scripting.
I was trying to use it temporarily as the simplest way to get a multi-domain LetsEncrypt cert on Windows, but ran out of time attempting to convert the resulting certificate format into something I could take back to IIS.
Those securing custom subdomains are looking forward to January 2018 when wildcard certificates arrive. https://letsencrypt.org/2017/07/06/wildcard-certificates-com...
https://fly.io/mix/custom-hostnames/
No affiliation on my part, the service has just ticked enough "ooh" boxes I'm intrigued and am looking at using them for a project or two
I chose not to use fly.io though, because I was ultimately putting control of the DNS settings for all of my SaaS's custom domains in their hands.
There's plenty of pre-written deployment scripts for it, check the wiki and Google. https://github.com/lukas2511/dehydrated
Failing that... If you're using Apache, it's on its way to natively supporting Let's Encrypt certificates for fully auto HTTPS https://letsencrypt.org/2017/10/17/acme-support-in-apache-ht...
Hope that helps. If you're not comfortable doing it yourself, any dev/sysadmin should be able to cobble it together for a days consultancy.
[1] https://valme.io/c/gettingstarted/69qqs/valme-io-now-with-cu... [2] https://letsencrypt.org/docs/client-options/
Edit: found a reference[0] on the tumblr help site:
>Keep in mind that enabling the option for a theme that wasn’t developed to support SSL may cause “mixed content” errors. If your blog looks weird after you turn SSL on, some resources that the theme needs to render itself may not be getting loaded.
>If you're a theme developer and you'd like to ensure your themes support SSL, make sure that any externally hosted resources such as Cascading Style Sheets (CSS) or Javascript files are served either using HTTPS or a protocol-relative URL. If these files aren’t available over HTTPS, consider uploading them at the Theme Customization page (In your blog settings, click “Edit HTML” and then “Theme assets”).
[0]: https://tumblr.zendesk.com/hc/en-us/articles/226273528-Encry...