Since transitioning to externalIPs for TCP services, it is no longer
possible to use the HTTP.01 ACME challenge to issue certificates for
services hosted in the cluster, because the ingress controller does not
listen on those addresses. Thus, we have to switch to using the DNS.01
challenge. I had avoided using it before because of the complexity of
managing dynamic DNS records with the Samba AD server, but this was
actually pretty to work around. I created a new DNS zone on the
firewall specifically for ACME challenges. Names in the AD-managed zone
have CNAME records for their corresponding *_acme-challenge* labels
pointing to this new zone. The new zone has dynamic updates enabled,
which _cert-manager_ supports using the RFC2136 plugin.
For now, this is only enabled for _rabbitmq.pyrocufflink.blue_. I will
transition the other names soon.
Dustin