Merge pull request #12776 from hashicorp/b-backend-config-change

command: recompute config hash with ConfigFile set

command/init_test.go

@@ -321,6 +321,38 @@ func TestInit_backendConfigFile(t *testing.T) {
 	}
 }
 
+func TestInit_backendConfigFileChange(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("init-backend-config-file-change"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	// Ask input
+	defer testInputMap(t, map[string]string{
+		"backend-migrate-to-new": "no",
+	})()
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	args := []string{"-backend-config", "input.config"}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	// Read our saved backend config and verify we have our settings
+	state := testStateRead(t, filepath.Join(DefaultDataDir, DefaultStateFilename))
+	if v := state.Backend.Config["path"]; v != "hello" {
+		t.Fatalf("bad: %#v", v)
+	}
+}
+
 func TestInit_copyBackendDst(t *testing.T) {
 	// Create a temporary working directory that is empty
 	td := tempDir(t)

command/meta_backend.go

@@ -302,6 +302,16 @@ func (m *Meta) backendFromConfig(opts *BackendOpts) (backend.Backend, error) {
 		return nil, fmt.Errorf("Error loading backend config: %s", err)
 	}
 
+	// cHash defaults to zero unless c is set
+	var cHash uint64
+	if c != nil {
+		// We need to rehash to get the value since we may have merged the
+		// config with an extra ConfigFile. We don't do this when merging
+		// because we do want the ORIGINAL value on c so that we store
+		// that to not detect drift. This is covered in tests.
+		cHash = c.Rehash()
+	}
+
 	// Get the path to where we store a local cache of backend configuration
 	// if we're using a remote backend. This may not yet exist which means
 	// we haven't used a non-local backend before. That is okay.
@@ -384,7 +394,7 @@ func (m *Meta) backendFromConfig(opts *BackendOpts) (backend.Backend, error) {
 	case c != nil && s.Remote.Empty() && !s.Backend.Empty():
 		// If our configuration is the same, then we're just initializing
 		// a previously configured remote backend.
-		if !s.Backend.Empty() && s.Backend.Hash == c.Hash {
+		if !s.Backend.Empty() && s.Backend.Hash == cHash {
 			return m.backend_C_r_S_unchanged(c, sMgr)
 		}
 
@@ -398,7 +408,7 @@ func (m *Meta) backendFromConfig(opts *BackendOpts) (backend.Backend, error) {
 
 		log.Printf(
 			"[WARN] command: backend config change! saved: %d, new: %d",
-			s.Backend.Hash, c.Hash)
+			s.Backend.Hash, cHash)
 		return m.backend_C_r_S_changed(c, sMgr, true)
 
 	// Configuring a backend for the first time while having legacy
@@ -420,7 +430,7 @@ func (m *Meta) backendFromConfig(opts *BackendOpts) (backend.Backend, error) {
 	case c != nil && !s.Remote.Empty() && !s.Backend.Empty():
 		// If the hashes are the same, we have a legacy remote state with
 		// an unchanged stored backend state.
-		if s.Backend.Hash == c.Hash {
+		if s.Backend.Hash == cHash {
 			if !opts.Init {
 				initReason := fmt.Sprintf(
 					"Legacy remote state found with configured backend %q",

command/test-fixtures/init-backend-config-file-change/.terraform/terraform.tfstate

@@ -0,0 +1,22 @@
+{
+    "version": 3,
+    "serial": 0,
+    "lineage": "666f9301-7e65-4b19-ae23-71184bb19b03",
+    "backend": {
+        "type": "local",
+        "config": {
+            "path": "local-state.tfstate"
+        },
+        "hash": 9073424445967744180
+    },
+    "modules": [
+        {
+            "path": [
+                "root"
+            ],
+            "outputs": {},
+            "resources": {},
+            "depends_on": []
+        }
+    ]
+}

command/test-fixtures/init-backend-config-file-change/input.config

@@ -0,0 +1 @@
+path = "hello"

command/test-fixtures/init-backend-config-file-change/main.tf

@@ -0,0 +1,5 @@
+terraform {
+    backend "local" {
+        path = "local-state.tfstate"
+    }
+}