Support the XDG Base Directory Specification (#1200)

Signed-off-by: Mario Valderrama <mario.valderrama@ionos.com>

CHANGELOG.md

@@ -16,6 +16,7 @@ ENHANCEMENTS:
 * Added "base64gunzip" function. ([$800](https://github.com/opentofu/opentofu/issues/800))
 * Added "cidrcontains" function. ([$366](https://github.com/opentofu/opentofu/issues/366))
 * Allow test run blocks to reference previous run block's module outputs ([#1129](https://github.com/opentofu/opentofu/pull/1129))
+* Support the XDG Base Directory Specification ([#1200](https://github.com/opentofu/opentofu/pull/1200))
 
 BUG FIXES:
 * `tofu test` resources cleanup at the end of tests changed to use simple reverse run block order. ([#1043](https://github.com/opentofu/opentofu/pull/1043))

cmd/tofu/main.go

@@ -501,7 +501,7 @@ func extractChdirOption(args []string) (string, []string, error) {
 }
 
 // Creates the the configuration directory.
-// `configDir` should refer to `~/.terraform.d` or its equivalent
+// `configDir` should refer to `~/.terraform.d`, `$XDG_CONFIG_HOME/opentofu` or its equivalent
 // on non-UNIX platforms.
 func mkConfigDir(configDir string) error {
 	err := os.Mkdir(configDir, os.ModePerm)

cmd/tofu/plugins.go

@@ -20,14 +20,16 @@ import (
 // older versions where both satisfy the provider version constraints.
 func globalPluginDirs() []string {
 	var ret []string
-	// Look in ~/.terraform.d/plugins/ , or its equivalent on non-UNIX
-	dir, err := cliconfig.ConfigDir()
+	// Look in ~/.terraform.d/plugins/, $XDG_DATA_HOME/opentofu/plugins, or its equivalent on non-UNIX platforms
+	dirs, err := cliconfig.DataDirs()
 	if err != nil {
-		log.Printf("[ERROR] Error finding global config directory: %s", err)
+		log.Printf("[ERROR] Error finding global plugin directories: %s", err)
 	} else {
 		machineDir := fmt.Sprintf("%s_%s", runtime.GOOS, runtime.GOARCH)
-		ret = append(ret, filepath.Join(dir, "plugins"))
-		ret = append(ret, filepath.Join(dir, "plugins", machineDir))
+		for _, dir := range dirs {
+			ret = append(ret, filepath.Join(dir, "plugins"))
+			ret = append(ret, filepath.Join(dir, "plugins", machineDir))
+		}
 	}
 
 	return ret

cmd/tofu/provider_source.go

@@ -96,7 +96,8 @@ func implicitProviderSource(services *disco.Disco) getproviders.Source {
 	//   way to include them in bundles uploaded to Terraform Cloud, where
 	//   there has historically otherwise been no way to use custom providers.
 	// - The "plugins" subdirectory of the CLI config search directory.
-	//   (thats ~/.terraform.d/plugins on Unix systems, equivalents elsewhere)
+	//   (thats ~/.terraform.d/plugins or $XDG_DATA_HOME/opentofu/plugins
+	//   on Unix systems, equivalents elsewhere)
 	// - The "plugins" subdirectory of any platform-specific search paths,
 	//   following e.g. the XDG base directory specification on Unix systems,
 	//   Apple's guidelines on OS X, and "known folders" on Windows.
@@ -144,9 +145,11 @@ func implicitProviderSource(services *disco.Disco) getproviders.Source {
 	}
 
 	addLocalDir("terraform.d/plugins") // our "vendor" directory
-	cliConfigDir, err := cliconfig.ConfigDir()
+	cliDataDirs, err := cliconfig.DataDirs()
 	if err == nil {
-		addLocalDir(filepath.Join(cliConfigDir, "plugins"))
+		for _, cliDataDir := range cliDataDirs {
+			addLocalDir(filepath.Join(cliDataDir, "plugins"))
+		}
 	}
 
 	// This "userdirs" library implements an appropriate user-specific and

internal/command/cliconfig/cliconfig.go

@@ -96,6 +96,11 @@ func ConfigDir() (string, error) {
 	return configDir()
 }
 
+// DataDirs returns the data directories for OpenTofu.
+func DataDirs() ([]string, error) {
+	return dataDirs()
+}
+
 // LoadConfig reads the CLI configuration from the various filesystem locations
 // and from the environment, returning a merged configuration along with any
 // diagnostics (errors and warnings) encountered along the way.

internal/command/cliconfig/config_unix.go

@@ -22,6 +22,11 @@ func configFile() (string, error) {
 	newConfigFile := filepath.Join(dir, ".tofurc")
 	legacyConfigFile := filepath.Join(dir, ".terraformrc")
 
+	if xdgDir := os.Getenv("XDG_CONFIG_HOME"); xdgDir != "" && !pathExists(legacyConfigFile) && !pathExists(newConfigFile) {
+		// a fresh install should not use terraform naming
+		return filepath.Join(xdgDir, "opentofu", "tofurc"), nil
+	}
+
 	return getNewOrLegacyPath(newConfigFile, legacyConfigFile)
 }
 
@@ -31,7 +36,26 @@ func configDir() (string, error) {
 		return "", err
 	}
 
-	return filepath.Join(dir, ".terraform.d"), nil
+	configDir := filepath.Join(dir, ".terraform.d")
+	if xdgDir := os.Getenv("XDG_CONFIG_HOME"); !pathExists(configDir) && xdgDir != "" {
+		configDir = filepath.Join(xdgDir, "opentofu")
+	}
+
+	return configDir, nil
+}
+
+func dataDirs() ([]string, error) {
+	dir, err := homeDir()
+	if err != nil {
+		return nil, err
+	}
+
+	dirs := []string{filepath.Join(dir, ".terraform.d")}
+	if xdgDir := os.Getenv("XDG_DATA_HOME"); xdgDir != "" {
+		dirs = append(dirs, filepath.Join(xdgDir, "opentofu"))
+	}
+
+	return dirs, nil
 }
 
 func homeDir() (string, error) {
@@ -40,7 +64,7 @@ func homeDir() (string, error) {
 		// FIXME: homeDir gets called from globalPluginDirs during init, before
 		// the logging is set up.  We should move meta initializtion outside of
 		// init, but in the meantime we just need to silence this output.
-		//log.Printf("[DEBUG] Detected home directory from env var: %s", home)
+		// log.Printf("[DEBUG] Detected home directory from env var: %s", home)
 
 		return home, nil
 	}
@@ -57,3 +81,8 @@ func homeDir() (string, error) {
 
 	return user.HomeDir, nil
 }
+
+func pathExists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}

internal/command/cliconfig/config_unix_test.go

@@ -0,0 +1,151 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+//go:build !windows
+// +build !windows
+
+package cliconfig
+
+import (
+	"os"
+	"path/filepath"
+	"slices"
+	"testing"
+)
+
+func TestConfigFileConfigDir(t *testing.T) {
+	homeDir := filepath.Join(t.TempDir(), "home")
+
+	tests := []struct {
+		name          string
+		xdgConfigHome string
+		files         []string
+		testFunc      func() (string, error)
+		expect        string
+	}{
+		{
+			name:     "configFile: use home tofurc",
+			testFunc: configFile,
+			files:    []string{filepath.Join(homeDir, ".tofurc")},
+			expect:   filepath.Join(homeDir, ".tofurc"),
+		},
+		{
+			name:     "configFile: use home terraformrc",
+			testFunc: configFile,
+			files:    []string{filepath.Join(homeDir, ".terraformrc")},
+			expect:   filepath.Join(homeDir, ".terraformrc"),
+		},
+		{
+			name:     "configFile: use default fallback",
+			testFunc: configFile,
+			expect:   filepath.Join(homeDir, ".tofurc"),
+		},
+		{
+			name:          "configFile: use XDG tofurc",
+			testFunc:      configFile,
+			xdgConfigHome: filepath.Join(homeDir, "xdg"),
+			expect:        filepath.Join(homeDir, "xdg", "opentofu", "tofurc"),
+		},
+		{
+			name:          "configFile: prefer home tofurc",
+			testFunc:      configFile,
+			xdgConfigHome: filepath.Join(homeDir, "xdg"),
+			files:         []string{filepath.Join(homeDir, ".tofurc")},
+			expect:        filepath.Join(homeDir, ".tofurc"),
+		},
+		{
+			name:          "configFile: prefer home terraformrc",
+			testFunc:      configFile,
+			xdgConfigHome: filepath.Join(homeDir, "xdg"),
+			files:         []string{filepath.Join(homeDir, ".terraformrc")},
+			expect:        filepath.Join(homeDir, ".terraformrc"),
+		},
+		{
+			name:     "configDir: use .terraform.d default",
+			testFunc: configDir,
+			expect:   filepath.Join(homeDir, ".terraform.d"),
+		},
+		{
+			name:          "configDir: prefer .terraform.d",
+			testFunc:      configDir,
+			xdgConfigHome: filepath.Join(homeDir, "xdg"),
+			files:         []string{filepath.Join(homeDir, ".terraform.d", "placeholder")},
+			expect:        filepath.Join(homeDir, ".terraform.d"),
+		},
+		{
+			name:          "configDir: use XDG value",
+			testFunc:      configDir,
+			xdgConfigHome: filepath.Join(homeDir, "xdg"),
+			expect:        filepath.Join(homeDir, "xdg", "opentofu"),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Setenv("HOME", homeDir)
+			t.Setenv("XDG_CONFIG_HOME", test.xdgConfigHome)
+			for _, f := range test.files {
+				createFile(t, f)
+			}
+
+			file, err := test.testFunc()
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if test.expect != file {
+				t.Fatalf("expected %q, but got %q", test.expect, file)
+			}
+		})
+	}
+}
+
+func TestDataDirs(t *testing.T) {
+	homeDir := filepath.Join(t.TempDir(), "home")
+
+	tests := []struct {
+		name        string
+		xdgDataHome string
+		expect      []string
+	}{
+		{
+			name:        "use XDG data dir",
+			xdgDataHome: filepath.Join(homeDir, "xdg"),
+			expect: []string{
+				filepath.Join(homeDir, ".terraform.d"),
+				filepath.Join(homeDir, "xdg", "opentofu"),
+			},
+		},
+		{
+			name: "use default",
+			expect: []string{
+				filepath.Join(homeDir, ".terraform.d"),
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Setenv("HOME", homeDir)
+			t.Setenv("XDG_DATA_HOME", test.xdgDataHome)
+
+			dirs, err := dataDirs()
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if !slices.Equal(test.expect, dirs) {
+				t.Fatalf("expected %+v, but got %+v", test.expect, dirs)
+			}
+		})
+	}
+}
+
+func createFile(t *testing.T, path string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = os.RemoveAll(filepath.Dir(path)) })
+}

internal/command/cliconfig/config_windows.go

@@ -40,6 +40,14 @@ func configDir() (string, error) {
 	return filepath.Join(dir, "terraform.d"), nil
 }
 
+func dataDirs() ([]string, error) {
+	dir, err := configDir()
+	if err != nil {
+		return nil, err
+	}
+	return []string{dir}, nil
+}
+
 func homeDir() (string, error) {
 	b := make([]uint16, syscall.MAX_PATH)
 

website/docs/cli/config/config-file.mdx

@@ -24,9 +24,12 @@ on the host operating system:
   If both `terraform.rc` and `tofu.rc` files exists, the later would take precedence.
 * On all other systems, the file must be named `.tofurc` (note
   the leading period) and placed directly in the home directory
-  of the relevant user.
+  of the relevant user or be named `tofurc` and placed in a valid
+  [XDG Base Directory](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html)
+  config directory such as `$XDG_CONFIG_HOME/opentofu`.
   The `.terraformrc` is supported for backward-compatability purposes.
-  If both `.terraformrc` and `.tofurc` files exists, the later would take precedence.
+  If both `.terraformrc` and `.tofurc` files exists, the latter would take precedence.
+  When using an XDG config directory `.terraformrc` and `terraformrc` are ignored.
 
 On Windows, beware of Windows Explorer's default behavior of hiding filename
 extensions. OpenTofu will not recognize a file named `tofuc.rc.txt` as a
@@ -275,12 +278,9 @@ the operating system where you are running OpenTofu:
   `~/Library/Application Support/io.terraform/plugins`, and
   `/Library/Application Support/io.terraform/plugins`
 * **Linux and other Unix-like systems**:`$HOME/.terraform.d/plugins` and
-  `terraform/plugins` located within a valid
+  `opentofu/plugins` located within a valid
   [XDG Base Directory](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html)
-  data directory such as `$XDG_DATA_HOME/terraform/plugins`.
-  Without any XDG environment variables set, OpenTofu will use
-  `~/.local/share/terraform/plugins`,
-  `/usr/local/share/terraform/plugins`, and `/usr/share/terraform/plugins`.
+  data directory such as `$XDG_DATA_HOME/opentofu/plugins`.
 
 If a `terraform.d/plugins` directory exists in the current working directory
 then OpenTofu will also include that directory, regardless of your operating

website/docs/language/resources/provisioners/syntax.mdx

@@ -195,7 +195,7 @@ provisioners must connect to the remote system using SSH or WinRM.
 You must include [a `connection` block](/docs/language/resources/provisioners/connection) so that OpenTofu knows how to communicate with the server.
 
 OpenTofu includes several built-in provisioners. You can also use third-party provisioners as plugins, by placing them
-in `%APPDATA%\terraform.d\plugins`, `~/.terraform.d/plugins`, or the same
+in `%APPDATA%\terraform.d\plugins`, `~/.terraform.d/plugins`, `$XDG_DATA_HOME/opentofu/plugins`, or the same
 directory where the OpenTofu binary is installed. However, we do not recommend
 using any provisioners except the built-in `file`, `local-exec`, and
 `remote-exec` provisioners.