How do you find the FQDN of the local host?

Question

How do you find the FQDN of the local host in Go?

BTW: net.LookupAddr() doesn't work on Windows. So that's not an option.

Answer 1

You can perform some gymnastics using the net lib as demonstrated here.

Answer 2

By default there is no short way.

os.Hostname() doesn't provide the Fully Qualified Domain Name by default.

cmd := exec.Command("/bin/hostname", "-f")
var out bytes.Buffer
cmd.Stdout = &out
err := cmd.Run()
if err != nil {
    log.Errorf(err)
}
fqdn := out.String()
fqdn = fqdn[:len(fqdn)-1] // removing EOL

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Answer 3

According to the documentation, function os.Hostname() returns the system host name reported by kernel. So, if your computer is named computer1, os.Hostname() returns computer1. If your computer is named computer1.my.office, os.Hostname() returns computer1.my.office. On Windows, is the same. If you want the domain name (as referred to the Active Directory domain) you have four ways:

1. Parse the result of this command: wmic computersystem get domain
2. Parse the result of this command: systeminfo | findstr /B /C:"Domain"
3. Assume the existence of the environment variable USERDNSDOMAIN and evaluate his value (note that: the value of this variable is referred at the domain which user is stored)
4. Check if one of the ip's assigned to the workstation can be resolved via DNS (for this point, you can view this: https://github.com/Showmax/go-fqdn)