Merge pull request #79 from andyz-dev/extra-log

[Enhancement] Log more information when the docker-machine command fails

cli/docker-machine.go

@@ -1,6 +1,7 @@
 package run
 
 import (
+	"log"
 	"os"
 	"os/exec"
 	"strings"
@@ -19,8 +20,16 @@ func getDockerMachineIp() (string, error) {
 	}
 
 	out, err := exec.Command(dockerMachinePath, "ip", machine).Output()
+	if err != nil {
+		log.Printf("Error executing 'docker-machine ip'")
 
+		if exitError, ok := err.(*exec.ExitError); ok {
+			log.Printf("%s", string(exitError.Stderr))
+		}
+		return "", err
+	}
 	ipStr := strings.TrimSuffix(string(out), "\n")
 	ipStr = strings.TrimSuffix(ipStr, "\r")
-	return ipStr, err
+
+	return ipStr, nil
 }