I'm settings up a Service Fabric cluster in Azure and want to run a web API (using .NET Core) over https. I want to use my CA-signed wildcard (*.mydomain.com) certificate to access this API. But I'm a bit confused as to where I use it when I create the cluster, is it the cluster or client certificate? I'm thinking the client certificate, but the documentation states that this is for admin tools (i.e. the Explorer), so I'm unsure on how to proceed.
And yes I've read a ton of posts and resources, but I still find this confusing.
There are three certificate types. Here is a summary overview of them.
The Cluster certificate is used for the Explorer endpoint and is deployed to the primary nodes. So if you add your *.mydomain.com wildcard cert there, and CNAME something (e.g. manage.mydomain.com) to [yourcluster].[region].cloudapp.azure.com, then when you hit your management endpoint that cert will be what will be presented to the web browser.
The Reverse Proxy SSL certificate is deployed to each of the nodes and is used when using the built-in reverse proxy feature of Service Fabric. In this case this is what is being used when you hit https://api.mydomain.com/YourAppName/YourService/Resource (where api.mydomain.com is another CNAME to yourcluster.region.cloudapp.azure.com). This is used as an alternative to running your own reverse proxy or other offloading layer (Application Gateway, IIS, nginx, API Management, etc).
The Client certificates are used in place of Azure Active Directory authentication to the management endpoint. So instead of managing users in AAD (with the _Cluster AAD application and the Admin / Read-Only roles), you manage access by handing out management certificates (Admin or Read-Only) to your trusted users.
You can also have secondaries these certificates to use in certificate rollover situations.