Merge pull request #283 from tianon/boot2docker.iso

Update default ISO path to prefer an ISO that's next to the boot2docker CLI binary

Author: SvenDowideit

config.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"regexp"
 	"runtime"
@@ -61,6 +62,36 @@ func cfgFilename(dir string) string {
 	return filename
 }
 
+func defaultIsoPath(dir string) string {
+	var err error
+
+	iso := filepath.Join(dir, "boot2docker.iso")
+
+	exe := os.Args[0]
+	if filepath.Base(exe) == exe {
+		// this logic borrowed from reexec/reexec.go in Docker itself :)
+		if lp, err := exec.LookPath(exe); err == nil {
+			exe = lp
+		}
+	}
+
+	if exe, err = filepath.Abs(exe); err != nil {
+		return iso
+	}
+
+	if exe, err = filepath.EvalSymlinks(exe); err != nil {
+		return iso
+	}
+
+	// if there's a "boot2docker.iso" next to our boot2docker-cli executable, let's prefer that one by default
+	exeIso := filepath.Join(filepath.Dir(exe), "boot2docker.iso")
+	if _, err = os.Stat(exeIso); err == nil {
+		return exeIso
+	}
+
+	return iso
+}
+
 // Write configuration set by the combination of profile and flags
 //    Should result in a format that can be piped into a profile file
 func printConfig() string {
@@ -92,7 +123,7 @@ func config() (*flag.FlagSet, error) {
 	//flags.StringVarP(&B2D.Dir, "dir", "d", dir, "boot2docker config directory.")
 	B2D.Dir = dir
 	flags.StringVar(&B2D.ISOURL, "iso-url", "https://api.github.com/repos/boot2docker/boot2docker/releases", "source URL to provision the boot2docker ISO image.")
-	flags.StringVar(&B2D.ISO, "iso", filepath.Join(dir, "boot2docker.iso"), "path to boot2docker ISO image.")
+	flags.StringVar(&B2D.ISO, "iso", defaultIsoPath(dir), "path to boot2docker ISO image.")
 
 	// Sven disabled this, as it is broken - if I user with a fresh computer downloads
 	// just the boot2docker-cli, and then runs `boot2docker --init ip`, we create a vm