Configuration overrides for krb5.conf

[Jimvin]

There will be occasions when we will want to add extra configuration to the Kerberos configuration file krb5.conf. An example would be when wishing to include additional realms in the configuration for accessing resources outside of the cluster.

This could be handled by allowing overriding or injection of additional properties to krb5.conf or by allowing the complete replacement of the krb5.conf provided by the Kerberos secret class.