config/module: git supports tags

config/module/get_git.go

@@ -16,15 +16,38 @@ func (g *GitGetter) Get(dst string, u *url.URL) error {
 		return fmt.Errorf("git must be available and on the PATH")
 	}
 
+	// Extract some query parameters we use
+	q := u.Query()
+	tag := q.Get("tag")
+	q.Del("tag")
+	u.RawQuery = q.Encode()
+
+	// First: clone or update the repository
 	_, err := os.Stat(dst)
 	if err != nil && !os.IsNotExist(err) {
 		return err
 	}
 	if err == nil {
-		return g.update(dst, u)
+		err = g.update(dst, u)
+	} else {
+		err = g.clone(dst, u)
+	}
+	if err != nil {
+		return err
 	}
 
-	return g.clone(dst, u)
+	// Next: check out the proper tag/branch if it is specified, and checkout
+	if tag == "" {
+		return nil
+	}
+
+	return g.checkout(dst, tag)
+}
+
+func (g *GitGetter) checkout(dst string, ref string) error {
+	cmd := exec.Command("git", "checkout", ref)
+	cmd.Dir = dst
+	return getRunCommand(cmd)
 }
 
 func (g *GitGetter) clone(dst string, u *url.URL) error {

config/module/get_git_test.go

@@ -49,3 +49,38 @@ func TestGitGetter(t *testing.T) {
 		t.Fatalf("err: %s", err)
 	}
 }
+
+func TestGitGetter_tag(t *testing.T) {
+	if !testHasGit {
+		t.Log("git not found, skipping")
+		t.Skip()
+	}
+
+	g := new(GitGetter)
+	dst := tempDir(t)
+
+	// Git doesn't allow nested ".git" directories so we do some hackiness
+	// here to get around that...
+	moduleDir := filepath.Join(fixtureDir, "basic-git")
+	oldName := filepath.Join(moduleDir, "DOTgit")
+	newName := filepath.Join(moduleDir, ".git")
+	if err := os.Rename(oldName, newName); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.Rename(newName, oldName)
+
+	url := testModuleURL("basic-git")
+	q := url.Query()
+	q.Add("tag", "v1.0")
+	url.RawQuery = q.Encode()
+
+	if err := g.Get(dst, url); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Verify the main file exists
+	mainPath := filepath.Join(dst, "main_tag1.tf")
+	if _, err := os.Stat(mainPath); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}

config/module/test-fixtures/basic-git/DOTgit/COMMIT_EDITMSG

@@ -1,10 +1,7 @@
-A commit
+remove tag1
 # Please enter the commit message for your changes. Lines starting
 # with '#' will be ignored, and an empty message aborts the commit.
 # On branch master
-#
-# Initial commit
-#
 # Changes to be committed:
-#	new file:   main.tf
+#	deleted:    main_tag1.tf
 #

config/module/test-fixtures/basic-git/DOTgit/logs/HEAD

@@ -1 +1,3 @@
 0000000000000000000000000000000000000000 497bc37401eb3c9b11865b1768725b64066eccee Mitchell Hashimoto <mitchell.hashimoto@gmail.com> 1410850637 -0700	commit (initial): A commit
+497bc37401eb3c9b11865b1768725b64066eccee 243f0fc5c4e586d1a3daa54c981b6f34e9ab1085 Mitchell Hashimoto <mitchell.hashimoto@gmail.com> 1410886526 -0700	commit: tag1
+243f0fc5c4e586d1a3daa54c981b6f34e9ab1085 1f31e97f053caeb5d6b7bffa3faf82941c99efa2 Mitchell Hashimoto <mitchell.hashimoto@gmail.com> 1410886536 -0700	commit: remove tag1

config/module/test-fixtures/basic-git/DOTgit/logs/refs/heads/master

@@ -1 +1,3 @@
 0000000000000000000000000000000000000000 497bc37401eb3c9b11865b1768725b64066eccee Mitchell Hashimoto <mitchell.hashimoto@gmail.com> 1410850637 -0700	commit (initial): A commit
+497bc37401eb3c9b11865b1768725b64066eccee 243f0fc5c4e586d1a3daa54c981b6f34e9ab1085 Mitchell Hashimoto <mitchell.hashimoto@gmail.com> 1410886526 -0700	commit: tag1
+243f0fc5c4e586d1a3daa54c981b6f34e9ab1085 1f31e97f053caeb5d6b7bffa3faf82941c99efa2 Mitchell Hashimoto <mitchell.hashimoto@gmail.com> 1410886536 -0700	commit: remove tag1

config/module/test-fixtures/basic-git/DOTgit/refs/heads/master

@@ -1 +1 @@
-497bc37401eb3c9b11865b1768725b64066eccee
+1f31e97f053caeb5d6b7bffa3faf82941c99efa2

config/module/test-fixtures/basic-git/DOTgit/refs/tags/v1.0

@@ -0,0 +1 @@
+243f0fc5c4e586d1a3daa54c981b6f34e9ab1085