<p>I am running a web service that can be accessed from my company's domain name.
I have setup automatic SSL certificates with Lets Encrypt as seen below.</p>

<p><code>apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: basic-ingress
  annotations: 
    certmanager.k8s.io/issuer: letsencrypt
spec:
  tls: 
  - hosts:
    - my.domain.net
    secretName: my-domain-net-tls 
  rules:
    - host: my.domain.net
      http:
        paths:
        - backend:
            serviceName: frontend-service
            servicePort: 80-to-8080-tcp
</code></p>

<p>I want to offer clients the option of serving the frontend from their own domains.
What is the best way to go about this with certificates?
I understand that I can setup the load balancer to use multiple secrets as shown here: <a href="https://cloud.google.com/kubernetes-engine/docs/how-to/ingress-multi-ssl" rel="nofollow noreferrer">https://cloud.google.com/kubernetes-engine/docs/how-to/ingress-multi-ssl</a>, 
but I will need to be serving from more than the stated max of 10 domains.</p>

<p>Is there a more efficient way to go about this? What's the industry standard for serving one frontend service from multiple domains?</p>

<p>Many thanks!</p>

<p>The standard method to support more than one domain name and / or subdomain names is to use one SSL Certificate and implement SAN (Subject Alternative Names). The extra domain names are stored together in the SAN. All SSL certificates support SAN, but not all certificate authorities will issue multi-domain certificates. Let's Encrypt does support SAN so their certificates will meet your goal.</p>

<p><a href="https://www.ssl.com/faqs/what-is-a-san-certificate/" rel="nofollow noreferrer">What is a SAN Certificate?</a></p>
