GoLang Scripting

_my_golang_script.go

//usr/bin/env true; go run `dirname $0`/*.go "$@"; exit $?
package main

import (
	"errors"
	"os"
)

// TODO: catch Panics and emit a clear message
func main() { os.Exit(mainWithExitCode()) }

func mainWithExitCode() int {
	var e error

	var r = "resource"
	var command string

	initLogging()

	switch command = getArg(1); command {
	case "create":
		command = "creating"
	case "destroy":
		command = "destroying"

	case "no-op":
	default:
		err("Unknown subcommand provided")
	}

	info(command + " " + r)

	e = errors.New("Not implemented")
	err(e)
	return 0
}

common.go

package main

import "os"

func isErr(e error) bool { return e != nil }

func getArg(n int) string {
	if len(os.Args) >= n+1 {
		return os.Args[n]
	}

	return ""
}

log.go

package main

import (
	"errors"
	"fmt"
	"os"
	"strconv"
)

func initEnv() {
	// Use our version of Kind binary to manage clusters
	os.Setenv("PATH", "./kind/bin:"+os.Getenv("PATH"))
}

func initLogging() {
	var name, val string
	var e error

	name = "DEBUG"
	if val = os.Getenv(name); val != "" {
		// Ignore error in parsing; we don't want to halt the app because of this
		if enableDebug, e = strconv.ParseBool(val); isErr(e) {
			enableDebug = enableDebugDefault
			warn("There was an error parsing the value of ", name, "; expected a boolean, got ", val)
		}
	}

	name = "EXIT_ON_ERROR"
	if val = os.Getenv(name); val != "" {
		// Ignore error in parsing; we don't want to halt the app because of this
		if exitOnError, e = strconv.ParseBool(val); isErr(e) {
			exitOnError = exitOnErrorDefault
			warn("There was an error parsing the value of ", name, "; expected a boolean, got ", val)
		}
	}
}

func debug(msg ...interface{}) {
	if enableDebug {
		_log("DEBUG", msg...)
	}
}

func info(msg ...interface{}) {
	_log("INFO", msg...)
}

func warn(msg ...interface{}) {
	_log("WARNING", msg...)
}

func err(msg ...interface{}) error {
	var loggedMsg = _log("ERROR", msg...)

	if exitOnError {
		os.Exit(1)
	}

	return errors.New(loggedMsg)
}

func fatal(msg ...interface{}) {
	_log("FATAL", msg...)
	panic("Exiting process. Panic!!!")
}

////////////////////////////////////////////////////////////////////////////////
// Supporting code follows; not to be used by code in other files
////////////////////////////////////////////////////////////////////////////////

func _log(prefix string, message ...interface{}) string {
	var msg = fmt.Sprint(append([]interface{}{prefix + ": "}, message...)...)
	fmt.Println(msg)
	return msg
}

const exitOnErrorDefault = true
const enableDebugDefault = true

// Similar to shell's `set -e` option
var exitOnError = exitOnErrorDefault
var enableDebug = enableDebugDefault