Merge pull request #30 from estesp/missing-rootfs-check

Make startup errors a bit friendlier

main.go

@@ -82,7 +82,6 @@ func main() {
 	// default action is to execute a container
 	app.Action = func(context *cli.Context) {
 		if os.Geteuid() != 0 {
-			cli.ShowAppHelp(context)
 			logrus.Fatal("runc should be run as root")
 		}
 		spec, err := loadSpec(context.Args().First())
@@ -91,7 +90,7 @@ func main() {
 		}
 		status, err := execContainer(context, spec)
 		if err != nil {
-			fatal(err)
+			logrus.Fatalf("Container start failed: %v", err)
 		}
 		// exit with the container's exit status so any external supervisor is
 		// notified of the exit with the correct exit status.

run.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
@@ -16,6 +17,12 @@ func execContainer(context *cli.Context, spec *LinuxSpec) (int, error) {
 	if err != nil {
 		return -1, err
 	}
+	if _, err := os.Stat(config.Rootfs); err != nil {
+		if os.IsNotExist(err) {
+			return -1, fmt.Errorf("Rootfs (%q) does not exist", config.Rootfs)
+		}
+		return -1, err
+	}
 	rootuid, err := config.HostUID()
 	if err != nil {
 		return -1, err