Add configuration option for terraform plugin dir (#787)

* Add configuration option for terraform plugin dir

Add test for format function

* Update comment

* Add integration test for plugin dir

* Update test to require an err if plugins aren't available

* Move defers to make sure we always cleanup

* Update init test to support Terraform 0.14

modules/terraform/format.go

@@ -87,6 +87,16 @@ func FormatTerraformLockAsArgs(lockCheck bool, lockTimeout string) []string {
 	return lockArgs
 }
 
+// FormatTerraformPluginDirAsArgs formats the plugin-dir variable
+// -plugin-dir
+func FormatTerraformPluginDirAsArgs(pluginDir string) []string {
+	pluginArgs := []string{fmt.Sprintf("-plugin-dir=%v", pluginDir)}
+	if pluginDir == "" {
+		return nil
+	}
+	return pluginArgs
+}
+
 // FormatTerraformArgs will format multiple args with the arg name (e.g. "-var-file", []string{"foo.tfvars", "bar.tfvars"})
 // returns "-var-file foo.tfvars -var-file bar.tfvars"
 func FormatTerraformArgs(argName string, args []string) []string {

modules/terraform/format_test.go

@@ -30,6 +30,24 @@ func TestFormatTerraformPlanFileAsArgs(t *testing.T) {
 	}
 }
 
+func TestFormatTerraformPluginDirAsArgs(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		dir      string
+		expected []string
+	}{
+		{"/some/plugin/dir", []string{"-plugin-dir=/some/plugin/dir"}},
+		{"", nil},
+	}
+
+	for _, testCase := range testCases {
+		checkResultWithRetry(t, 100, testCase.expected, fmt.Sprintf("FormatTerraformPluginDirAsArgs(%v)", testCase.dir), func() interface{} {
+			return FormatTerraformPluginDirAsArgs(testCase.dir)
+		})
+	}
+}
+
 func TestFormatTerraformVarsAsArgs(t *testing.T) {
 	t.Parallel()
 

modules/terraform/init.go

@@ -19,5 +19,6 @@ func Init(t testing.TestingT, options *Options) string {
 func InitE(t testing.TestingT, options *Options) (string, error) {
 	args := []string{"init", fmt.Sprintf("-upgrade=%t", options.Upgrade)}
 	args = append(args, FormatTerraformBackendConfigAsArgs(options.BackendConfig)...)
+	args = append(args, FormatTerraformPluginDirAsArgs(options.PluginDir)...)
 	return RunTerraformCommandE(t, options, args...)
 }

modules/terraform/init_test.go

@@ -2,11 +2,13 @@ package terraform
 
 import (
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 
 	"github.com/gruntwork-io/terratest/modules/files"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestInitBackendConfig(t *testing.T) {
@@ -35,3 +37,48 @@ func TestInitBackendConfig(t *testing.T) {
 
 	assert.FileExists(t, remoteStateFile)
 }
+
+func TestInitPluginDir(t *testing.T) {
+	t.Parallel()
+
+	testingDir, err := ioutil.TempDir("", t.Name())
+	require.NoError(t, err)
+	defer os.RemoveAll(testingDir)
+
+	terraformFixture := "../../test/fixtures/terraform-basic-configuration"
+
+	initializedFolder, err := files.CopyTerraformFolderToTemp(terraformFixture, t.Name())
+	require.NoError(t, err)
+	defer os.RemoveAll(initializedFolder)
+
+	testFolder, err := files.CopyTerraformFolderToTemp(terraformFixture, t.Name())
+	require.NoError(t, err)
+	defer os.RemoveAll(testFolder)
+
+	terraformOptions := &Options{
+		TerraformDir: initializedFolder,
+	}
+
+	terraformOptionsPluginDir := &Options{
+		TerraformDir: testFolder,
+		PluginDir:    testingDir,
+	}
+
+	Init(t, terraformOptions)
+
+	_, err = InitE(t, terraformOptionsPluginDir)
+	require.Error(t, err)
+
+	// In Terraform 0.13, the directory is "plugins"
+	initializedPluginDir := initializedFolder + "/.terraform/plugins"
+
+	// In Terraform 0.14, the directory is "providers"
+	initializedProviderDir := initializedFolder + "/.terraform/providers"
+
+	files.CopyFolderContents(initializedPluginDir, testingDir)
+	files.CopyFolderContents(initializedProviderDir, testingDir)
+
+	initOutput := Init(t, terraformOptionsPluginDir)
+
+	assert.Contains(t, initOutput, "(unauthenticated)")
+}

modules/terraform/options.go

@@ -67,6 +67,7 @@ type Options struct {
 	Logger                   *logger.Logger         // Set a non-default logger that should be used. See the logger package for more info.
 	Parallelism              int                    // Set the parallelism setting for Terraform
 	PlanFilePath             string                 // The path to output a plan file to (for the plan command) or read one from (for the apply command)
+	PluginDir                string                 // The path of downloaded plugins to pass to the terraform init command (-plugin-dir)
 }
 
 // Clone makes a deep copy of most fields on the Options object and returns it.