Traditionally VMware Cloud Foundation (VCF) has followed the hybrid approach when it comes to SSL certificate management. Hybrid mode essentially means using CA signed certs for the vCenter Server machineSSL cert, and VMCA signed certs for the solution user certs. In this mode, ESXi host certs are VMCA managed also. You then have the option to integrate with an external Microsoft CA or continue to use VMCA for all certs. If you decide to integrate with a Microsoft CA, ESXi host certs remain VMCA managed. This is not always ideal as some customers require all components on the network to be signed by a known & trusted CA. Up until the recent 4.1 VMware Cloud Foundation (VCF) release it was not possible to use custom CA signed certs on your ESXi hosts, as hybrid mode would overwrite your CA signed ESXi certs with VMCA signed certs. There is a great blog post here on how to manually enable CA signed certs here but with VCF 4.1 it is now supported to do this via the API during bringup. The procedure is as follows:

 

1. Install the ESXi hosts that will be used for bringup with the ESXi version on the Bill Of Materials for 4.1
2. Install your custom CA signed certs on each host that will be used for the management domain
   1. Log in to the ESXi Shell, either directly from the DCUI or from an SSH client, as a user with administrator privileges.
   2. In the directory /etc/vmware/ssl, rename the existing certificates using the following commands.

      mv rui.crt orig.rui.crt 
      mv rui.key orig.rui.key
      

   3. Copy the certificates that you want to use to /etc/vmware/ssl.
   4. Rename the new certificate and key to rui.crt and rui.key.
   5. Restart the host management agents by running the following commands

 /etc/init.d/hostd restart /etc/init.d/vpxa restart 

Repeat the above steps for all management domain hosts

To ensure that SDDC Manager is aware that you are using custom certs you need to add a flag in the bringup json along with the PEM encoded signing chain certificate, so that it is added to the SDDC Manager keystore. This will ensure the certificates are trusted. The API guide for 4.1 provides an example json spec here. Pay particular attention to this section

securitySpec" : {
"esxiCertsMode" : "One among:Custom, VMCA",
"rootCaCerts" : [ {
"alias" : "string",
"certChain" : [ "string" ]
} ]
}

So to enable support for signed certs you would set this section as follows (Substituting your signing CA chain)

 securitySpec" : { 
"esxiCertsMode" : "Custom", 
"rootCaCerts" : [ { 
"alias" : "Rainpole-CA", 
"certChain" : [ "-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----" ] } ] } 

 

 

You can then follow the steps outlined in the API guide to deploy the management domain using the Cloud Builder API. Note that once custom mode is enabled, all future workload domains that you create must also use signed certs.