Use alternate temp directories for docker

The temporary directories will be created under the packer config
directory. Setting PACKER_TMP_DIR will override this path.

builder/docker/step_temp_dir.go

@@ -18,7 +18,14 @@ func (s *StepTempDir) Run(state multistep.StateBag) multistep.StepAction {
 	ui := state.Get("ui").(packer.Ui)
 
 	ui.Say("Creating a temporary directory for sharing data...")
-	td, err := ioutil.TempDir("", "packer-docker")
+
+	var err error
+	var tempdir string
+
+	configTmpDir, err := packer.ConfigTmpDir()
+	if err == nil {
+		tempdir, err = ioutil.TempDir(configTmpDir, "packer-docker")
+	}
 	if err != nil {
 		err := fmt.Errorf("Error making temp dir: %s", err)
 		state.Put("error", err)
@@ -26,7 +33,7 @@ func (s *StepTempDir) Run(state multistep.StateBag) multistep.StepAction {
 		return multistep.ActionHalt
 	}
 
-	s.tempDir = td
+	s.tempDir = tempdir
 	state.Put("temp_dir", s.tempDir)
 	return multistep.ActionContinue
 }

builder/docker/step_temp_dir_test.go

@@ -1,16 +1,19 @@
 package docker
 
 import (
-	"github.com/mitchellh/multistep"
 	"os"
+	"path/filepath"
 	"testing"
+
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
 )
 
 func TestStepTempDir_impl(t *testing.T) {
 	var _ multistep.Step = new(StepTempDir)
 }
 
-func TestStepTempDir(t *testing.T) {
+func testStepTempDir_impl(t *testing.T) string {
 	state := testState(t)
 	step := new(StepTempDir)
 	defer step.Cleanup(state)
@@ -41,4 +44,53 @@ func TestStepTempDir(t *testing.T) {
 	if _, err := os.Stat(dir); err == nil {
 		t.Fatalf("dir should be gone")
 	}
+
+	return dir
+}
+
+func TestStepTempDir(t *testing.T) {
+	testStepTempDir_impl(t)
+}
+
+func TestStepTempDir_notmpdir(t *testing.T) {
+	tempenv := "PACKER_TMP_DIR"
+
+	oldenv := os.Getenv(tempenv)
+	defer os.Setenv(tempenv, oldenv)
+	os.Setenv(tempenv, "")
+
+	dir1 := testStepTempDir_impl(t)
+
+	cd, err := packer.ConfigDir()
+	if err != nil {
+		t.Fatalf("bad ConfigDir")
+	}
+	td := filepath.Join(cd, "tmp")
+	os.Setenv(tempenv, td)
+
+	dir2 := testStepTempDir_impl(t)
+
+	if filepath.Dir(dir1) != filepath.Dir(dir2) {
+		t.Fatalf("temp base directories do not match: %s %s", filepath.Dir(dir1), filepath.Dir(dir2))
+	}
+}
+
+func TestStepTempDir_packertmpdir(t *testing.T) {
+	tempenv := "PACKER_TMP_DIR"
+
+	oldenv := os.Getenv(tempenv)
+	defer os.Setenv(tempenv, oldenv)
+	os.Setenv(tempenv, ".")
+
+	dir1 := testStepTempDir_impl(t)
+
+	abspath, err := filepath.Abs(".")
+	if err != nil {
+		t.Fatalf("bad absolute path")
+	}
+	dir2 := filepath.Join(abspath, "tmp")
+
+	if filepath.Dir(dir1) != filepath.Dir(dir2) {
+		t.Fatalf("temp base directories do not match: %s %s", filepath.Dir(dir1), filepath.Dir(dir2))
+	}
 }

packer/config_file.go

@@ -1,5 +1,10 @@
 package packer
 
+import (
+	"os"
+	"path/filepath"
+)
+
 // ConfigFile returns the default path to the configuration file. On
 // Unix-like systems this is the ".packerconfig" file in the home directory.
 // On Windows, this is the "packer.config" file in the application data
@@ -12,3 +17,24 @@ func ConfigFile() (string, error) {
 func ConfigDir() (string, error) {
 	return configDir()
 }
+
+// ConfigTmpDir returns the configuration tmp directory for Packer
+func ConfigTmpDir() (string, error) {
+	if tmpdir := os.Getenv("PACKER_TMP_DIR"); tmpdir != "" {
+		return filepath.Abs(tmpdir)
+	}
+	configdir, err := configDir()
+	if err != nil {
+		return "", err
+	}
+	td := filepath.Join(configdir, "tmp")
+	_, err = os.Stat(td)
+	if os.IsNotExist(err) {
+		if err = os.MkdirAll(td, 0755); err != nil {
+			return "", err
+		}
+	} else if err != nil {
+		return "", err
+	}
+	return td, nil
+}