Reliably access a file that resides next to the code/binary, whether it's started via go run or go build

file_path_build_vs_run.go

package main

import (
	"fmt"
	"os"

	log "github.com/sirupsen/logrus"
)

func main() {
    p := getCorrectPath
    fmt.Println(p)
}

func getCorrectPath(filename string) string {
    // Example: A file resides in the src directory, next to the code

	// IF compiled via `go build ...` and then invoked via program start
	//   The file should then reside next to the "main" executable
	//   os.Executable() points to the executable, everything is fine

	// IF invoked via `go run ...` from current working dir "src/"
	//   In this case the file can NOT be found next to the executable
	//   os.Executable() points to a temporary directory like "/var/folders/h8/yc69bl5x56n4772z7yyw1xj00000gn/T/go-build682711541/b001/exe/..."
	//   So here filepath.Abs("./") has to be used
	//   A side effect is that this does not work if started from other pwd than "src"

	exPath, err := os.Executable()
	FailOnError(err, "Can't get path to the executable")
	crossPlatformPath := filepath.FromSlash(filepath.Dir(exPath) + "/" + filename)

	if _, err := os.Stat(crossPlatformPath); os.IsNotExist(err) {
		log.WithFields(log.Fields{
			"crossPlatformPath": crossPlatformPath,
			"executablePath":    exPath,
			"filename":          filename,
		}).Warning("File not found at preferred location")

		exPath, err = filepath.Abs("./")
		FailOnError(err, "Can't get path to the executable")
		crossPlatformPath = filepath.FromSlash(exPath + "/" + filename)

		if _, err := os.Stat(crossPlatformPath); os.IsNotExist(err) {
			log.WithFields(log.Fields{
				"crossPlatformPath": crossPlatformPath,
				"executablePath":    exPath,
				"filename":          filename,
			}).Fatal("File not found at alternate location")
		}
	}

	log.WithFields(log.Fields{
		"crossPlatformPath": crossPlatformPath,
		"executablePath":    exPath,
		"filename":          filename,
	}).Info("File found")

	return crossPlatformPath
}