Golang get fully qualified domain name / hostname

binwu.go

package main

import (
    "fmt"
    "os"
    "os/exec"
    "strings"
    "bytes"
    //"time"
)

func get_hostname(hostname_override string) (string, error) {
    hostname := hostname_override
    if len(hostname) == 0 {
        node_name, err := os.Hostname()
        if err != nil {
            return "", fmt.Errorf("couldn't determine hostname: %v", err)
        }

        hostname = node_name
    }

    hostname = strings.TrimSpace(hostname)

    if len(hostname) == 0 {
        return "", fmt.Errorf("empty hostname is invalid")
    }

    return strings.ToLower(hostname), nil
}

func get_hostname_fqdn() (string, error) {
    cmd := exec.Command("/bin/hostname", "-f")
    var out bytes.Buffer
    cmd.Stdout = &out
    err := cmd.Run()
    if err != nil {
        return  "", fmt.Errorf("Error when get_hostname_fqdn: %v", err)
    }
    fqdn := out.String()
    fqdn = fqdn[:len(fqdn)-1] // removing EOL

    return fqdn, nil
}

func main() {
    hostname, err := get_hostname("bindigo.internal")
    // hostname, err := get_hostname("")

    if err != nil {
        return
    }

    fmt.Println("hostname: " + hostname)

    hn_fqdn, err := get_hostname_fqdn()
    fmt.Println("hostname_fqdn: " + hn_fqdn)
}

run

#!/bin/bash -ex

go build binwu.go

./binwu

Thanks for sharing this. I landed here from a Google search for "golang get hostname".

You may also find the approach used here useful: https://github.com/Showmax/go-fqdn.

They've opted to try DNS for the fqdn and then fallback to the local hostname, then finally "unknown" if not available via either approach. Extending their approach by calling out to /bin/hostname (if present) could provide yet another fallback option before giving up and providing a default response.

Thanks for sharing this. I landed here from a Google search for "golang get hostname".

You may also find the approach used here useful: https://github.com/Showmax/go-fqdn.

They've opted to try DNS for the fqdn and then fallback to the local hostname, then finally "unknown" if not available via either approach. Extending their approach by calling out to /bin/hostname (if present) could provide yet another fallback option before giving up and providing a default response.

Appreciated your information 👍 love it