title: SSL for custom client domains
body: <p>I have an app (hosted in heroku) where customers have an individual subdomain e.g. <code>client1.myapp.com</code>, <code>client2.myapp.com</code> I am using a wildcard SSL cert here.</p>
  
  <p>If however a client wants to use their own custom domain e.g. <code>CNAME</code> <code>app.client1.com</code> </p>
  
  <p>How can i automatically provide an SSL cert (I'm guessing using Lets Encrypt) for the client without them providing me a certificate to upload in a similar way to firebase etc.. provides SSL certs for  domains.</p>