set default HOME env properly (#341)

* set default HOME env properly

* set HOME to / if user is set by uid

* fix test

* continue to skip user_run test

* fix unit test to match new functionality

integration/dockerfiles/Dockerfile_test_user_run

@@ -20,8 +20,12 @@ RUN echo "hey" > /tmp/foo
 USER testuser:1001
 RUN echo "hey2" >> /tmp/foo
 
+USER root
+
 RUN useradd -ms /bin/bash newuser
 USER newuser
 RUN echo "hi" > $HOME/file
 COPY context/foo $HOME/foo
 
+USER 1001
+RUN echo $HOME

pkg/commands/run.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"os/user"
 	"strconv"
 	"strings"
 	"syscall"
@@ -116,19 +117,29 @@ func (r *RunCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 }
 
 // addDefaultHOME adds the default value for HOME if it isn't already set
-func addDefaultHOME(user string, envs []string) []string {
+func addDefaultHOME(u string, envs []string) []string {
 	for _, env := range envs {
 		split := strings.SplitN(env, "=", 2)
 		if split[0] == constants.HOME {
 			return envs
 		}
 	}
+
 	// If user isn't set, set default value of HOME
-	if user == "" {
+	if u == "" {
 		return append(envs, fmt.Sprintf("%s=%s", constants.HOME, constants.DefaultHOMEValue))
 	}
-	// If user is set, set value of HOME to /home/${user}
+
-	return append(envs, fmt.Sprintf("%s=/home/%s", constants.HOME, user))
+	// If user is set to username, set value of HOME to /home/${user}
+	// Otherwise the user is set to uid and HOME is /
+	home := fmt.Sprintf("%s=/", constants.HOME)
+	userObj, err := user.Lookup(u)
+	if err == nil {
+		u = userObj.Username
+		home = fmt.Sprintf("%s=/home/%s", constants.HOME, u)
+	}
+
+	return append(envs, home)
 }
 
 // FilesToSnapshot returns nil for this command because we don't know which files

pkg/commands/run_test.go

@@ -59,7 +59,7 @@ func Test_addDefaultHOME(t *testing.T) {
 			},
 			expected: []string{
 				"PATH=/something/else",
-				"HOME=/home/newuser",
+				"HOME=/",
 			},
 		},
 	}