Add support for autodetected HOME from USER (if HOME is unset)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

builder/builder.go

@@ -120,7 +120,7 @@ func (b *buildFile) CmdFrom(name string) error {
 		b.config = image.Config
 	}
 	if b.config.Env == nil || len(b.config.Env) == 0 {
-		b.config.Env = append(b.config.Env, "HOME=/", "PATH="+daemon.DefaultPathEnv)
+		b.config.Env = append(b.config.Env, "PATH="+daemon.DefaultPathEnv)
 	}
 	// Process ONBUILD triggers if they exist
 	if nTriggers := len(b.config.OnBuild); nTriggers != 0 {

daemon/container.go

@@ -1043,9 +1043,12 @@ func (container *Container) setupLinkedContainers() ([]string, error) {
 func (container *Container) createDaemonEnvironment(linkedEnv []string) []string {
 	// Setup environment
 	env := []string{
-		"HOME=/",
 		"PATH=" + DefaultPathEnv,
 		"HOSTNAME=" + container.Config.Hostname,
+		// Note: we don't set HOME here because it'll get autoset intelligently
+		// based on the value of USER inside dockerinit, but only if it isn't
+		// set already (ie, that can be overridden by setting HOME via -e or ENV
+		// in a Dockerfile).
 	}
 	if container.Config.Tty {
 		env = append(env, "TERM=xterm")

integration-cli/docker_cli_build_test.go

@@ -700,7 +700,7 @@ func TestBuildRelativeWorkdir(t *testing.T) {
 
 func TestBuildEnv(t *testing.T) {
 	name := "testbuildenv"
-	expected := "[HOME=/ PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PORT=2375]"
+	expected := "[PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PORT=2375]"
 	defer deleteImages(name)
 	_, err := buildImage(name,
 		`FROM busybox

integration-cli/docker_cli_run_test.go

@@ -676,13 +676,13 @@ func TestEnvironment(t *testing.T) {
 
 	goodEnv := []string{
 		"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
-		"HOME=/",
 		"HOSTNAME=testing",
 		"FALSE=true",
 		"TRUE=false",
 		"TRICKY=tri",
 		"cky",
 		"",
+		"HOME=/root",
 	}
 	sort.Strings(goodEnv)
 	if len(goodEnv) != len(actualEnv) {