the dns_canonicalize_hostname value not being respected

[alanhe]

According to the doc: https://web.mit.edu/kerberos/krb5-devel/doc/admin/princ_dns.html#service-principal-canonicalization

If dns_canonicalize_hostname is set to true (the default value), the client performs forward resolution by looking up the IPv4 and/or IPv6 addresses of the hostname using getaddrinfo(). This process will typically add a domain suffix to the hostname if needed, and follow CNAME records in the DNS.

When doing kerberos authentication, gokrb5 reads the dns_canonicalize_hostname value and set DNSCanonicalizeHostname to true (https://github.com/jcmturner/gokrb5/blob/master/v8/config/krb5conf.go#LL182C1-L182C1), but it's not read by github.com/colinmarc/hdfs/v2. The hdfs lib does Kerberos handshake with the name node hostnames in hdfs-site.xml, not resolving to their CNAMEs.

It bothers me when the name nodes are registered by their FQDNs, but their LB names are set in the hdfs-site.xml -- something I'm no able to change.

I can bypass the issue by running net.LookupCNAME to overwrite the ClientOptions.Addresses before initializing a client, but I think it will be great if it can be handled inside the lib.