command/init: check required_version

Previously we were checking required_version only during "real" operations, and not during initialization. Catching it during init is better because that's the first command users run on a new working directory.

command/init.go

@@ -288,6 +288,11 @@ func (c *InitCommand) getProviders(path string, state *terraform.State, upgrade
 		return err
 	}
 
+	if err := terraform.CheckRequiredVersion(mod); err != nil {
+		c.Ui.Error(err.Error())
+		return err
+	}
+
 	var available discovery.PluginMetaSet
 	if upgrade {
 		// If we're in upgrade mode, we ignore any auto-installed plugins

command/init_test.go

@@ -855,6 +855,27 @@ func TestInit_getProviderHaveLegacyVersion(t *testing.T) {
 	}
 }
 
+func TestInit_getProviderCheckRequiredVersion(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("init-check-required-version"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	args := []string{}
+	if code := c.Run(args); code != 1 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+}
+
 func TestInit_providerLockFile(t *testing.T) {
 	// Create a temporary working directory that is empty
 	td := tempDir(t)

command/test-fixtures/init-check-required-version/main.tf

@@ -0,0 +1,3 @@
+terraform {
+    required_version = "~> 0.9.0"
+}

terraform/context.go

@@ -122,7 +122,7 @@ type Context struct {
 func NewContext(opts *ContextOpts) (*Context, error) {
 	// Validate the version requirement if it is given
 	if opts.Module != nil {
-		if err := checkRequiredVersion(opts.Module); err != nil {
+		if err := CheckRequiredVersion(opts.Module); err != nil {
 			return nil, err
 		}
 	}

terraform/version_required.go

@@ -8,17 +8,17 @@ import (
 	"github.com/hashicorp/terraform/config/module"
 )
 
-// checkRequiredVersion verifies that any version requirements specified by
+// CheckRequiredVersion verifies that any version requirements specified by
 // the configuration are met.
 //
 // This checks the root module as well as any additional version requirements
 // from child modules.
 //
 // This is tested in context_test.go.
-func checkRequiredVersion(m *module.Tree) error {
+func CheckRequiredVersion(m *module.Tree) error {
 	// Check any children
 	for _, c := range m.Children() {
-		if err := checkRequiredVersion(c); err != nil {
+		if err := CheckRequiredVersion(c); err != nil {
 			return err
 		}
 	}