config/module: use the raw source as part of the key

This changes the key for the storage to be the _raw_ source from the
module, not the fully expanded source. Example: it'll be a relative path
instead of an absolute path.

This allows the ".terraform/modules" directory to be portable when
moving to other machines. This was a behavior that existed in <= 0.7.2
and was broken with #8398. This amends that and adds a test to verify.

config/module/tree.go

@@ -170,7 +170,7 @@ func (t *Tree) Load(s getter.Storage, mode GetMode) error {
 
 		// Get the directory where this module is so we can load it
 		key := strings.Join(path, ".")
-		key = fmt.Sprintf("root.%s-%s", key, source)
+		key = fmt.Sprintf("root.%s-%s", key, m.Source)
 		dir, ok, err := getStorage(s, key, source, mode)
 		if err != nil {
 			return err

config/module/tree_test.go

@@ -1,9 +1,13 @@
 package module
 
 import (
+	"os"
 	"reflect"
 	"strings"
 	"testing"
+
+	"github.com/hashicorp/go-getter"
+	"github.com/hashicorp/terraform/helper/copy"
 )
 
 func TestTreeChild(t *testing.T) {
@@ -102,6 +106,49 @@ func TestTreeLoad_duplicate(t *testing.T) {
 	}
 }
 
+func TestTreeLoad_copyable(t *testing.T) {
+	dir := tempDir(t)
+	storage := &getter.FolderStorage{StorageDir: dir}
+	tree := NewTree("", testConfig(t, "basic"))
+
+	// This should get things
+	if err := tree.Load(storage, GetModeGet); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if !tree.Loaded() {
+		t.Fatal("should be loaded")
+	}
+
+	// This should no longer error
+	if err := tree.Load(storage, GetModeNone); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Now we copy the directory, this COPIES symlink values, and
+	// doesn't create symlinks themselves. That is important.
+	dir2 := tempDir(t)
+	os.RemoveAll(dir2)
+	if err := copy.CopyDir(dir, dir2); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Create a new tree just to be sure
+	{
+		tree := NewTree("", testConfig(t, "basic"))
+		storage := &getter.FolderStorage{StorageDir: dir2}
+
+		// This should not error since we already got it!
+		if err := tree.Load(storage, GetModeNone); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		if !tree.Loaded() {
+			t.Fatal("should be loaded")
+		}
+	}
+}
+
 func TestTreeLoad_parentRef(t *testing.T) {
 	storage := testStorage(t)
 	tree := NewTree("", testConfig(t, "basic-parent"))

helper/copy/copy.go

@@ -0,0 +1,121 @@
+package copy
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// From: https://gist.github.com/m4ng0squ4sh/92462b38df26839a3ca324697c8cba04
+
+// CopyFile copies the contents of the file named src to the file named
+// by dst. The file will be created if it does not already exist. If the
+// destination file exists, all it's contents will be replaced by the contents
+// of the source file. The file mode will be copied from the source and
+// the copied data is synced/flushed to stable storage.
+func CopyFile(src, dst string) (err error) {
+	in, err := os.Open(src)
+	if err != nil {
+		return
+	}
+	defer in.Close()
+
+	out, err := os.Create(dst)
+	if err != nil {
+		return
+	}
+	defer func() {
+		if e := out.Close(); e != nil {
+			err = e
+		}
+	}()
+
+	_, err = io.Copy(out, in)
+	if err != nil {
+		return
+	}
+
+	err = out.Sync()
+	if err != nil {
+		return
+	}
+
+	si, err := os.Stat(src)
+	if err != nil {
+		return
+	}
+	err = os.Chmod(dst, si.Mode())
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+// CopyDir recursively copies a directory tree, attempting to preserve permissions.
+// Source directory must exist, destination directory must *not* exist.
+// Symlinks are ignored and skipped.
+func CopyDir(src string, dst string) (err error) {
+	src = filepath.Clean(src)
+	dst = filepath.Clean(dst)
+
+	si, err := os.Stat(src)
+	if err != nil {
+		return err
+	}
+	if !si.IsDir() {
+		return fmt.Errorf("source is not a directory")
+	}
+
+	_, err = os.Stat(dst)
+	if err != nil && !os.IsNotExist(err) {
+		return
+	}
+	if err == nil {
+		return fmt.Errorf("destination already exists")
+	}
+
+	err = os.MkdirAll(dst, si.Mode())
+	if err != nil {
+		return
+	}
+
+	entries, err := ioutil.ReadDir(src)
+	if err != nil {
+		return
+	}
+
+	for _, entry := range entries {
+		srcPath := filepath.Join(src, entry.Name())
+		dstPath := filepath.Join(dst, entry.Name())
+
+		// If the entry is a symlink, we copy the contents
+		for entry.Mode()&os.ModeSymlink != 0 {
+			target, err := os.Readlink(srcPath)
+			if err != nil {
+				return err
+			}
+
+			entry, err = os.Stat(target)
+			if err != nil {
+				return err
+			}
+		}
+
+		if entry.IsDir() {
+			err = CopyDir(srcPath, dstPath)
+			if err != nil {
+				return
+			}
+		} else {
+			err = CopyFile(srcPath, dstPath)
+			if err != nil {
+				return
+			}
+		}
+	}
+
+	return
+}