Merge pull request #13825 from hashicorp/jbardin/reconfigure

add init -reconfigure flag

command/init.go

@@ -30,6 +30,7 @@ func (c *InitCommand) Run(args []string) int {
 	cmdFlags.BoolVar(&c.forceInitCopy, "force-copy", false, "suppress prompts about copying state data")
 	cmdFlags.BoolVar(&c.Meta.stateLock, "lock", true, "lock state")
 	cmdFlags.DurationVar(&c.Meta.stateLockTimeout, "lock-timeout", 0, "lock timeout")
+	cmdFlags.BoolVar(&c.reconfigure, "reconfigure", false, "reconfigure")
 
 	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
 	if err := cmdFlags.Parse(args); err != nil {
@@ -223,6 +224,10 @@ Options:
                        times. The backend type must be in the configuration
                        itself.
 
+  -force-copy          Suppress prompts about copying state data. This is
+                       equivalent to providing a "yes" to all confirmation
+                       prompts.
+
   -get=true            Download any modules for this configuration.
 
   -input=true          Ask for input if necessary. If false, will error if
@@ -234,9 +239,7 @@ Options:
 
   -no-color            If specified, output won't contain any color.
 
-  -force-copy          Suppress prompts about copying state data. This is
-                       equivalent to providing a "yes" to all confirmation
-                       prompts.
+  -reconfigure          Reconfigure the backend, ignoring any saved configuration.
 `
 	return strings.TrimSpace(helpText)
 }

command/meta.go

@@ -95,6 +95,8 @@ type Meta struct {
 	//
 	// forceInitCopy suppresses confirmation for copying state data during
 	// init.
+	//
+	// reconfigure forces init to ignore any stored configuration.
 	statePath        string
 	stateOutPath     string
 	backupPath       string
@@ -104,6 +106,7 @@ type Meta struct {
 	stateLock        bool
 	stateLockTimeout time.Duration
 	forceInitCopy    bool
+	reconfigure      bool
 }
 
 // initStatePaths is used to initialize the default values for

command/meta_backend.go

@@ -352,6 +352,13 @@ func (m *Meta) backendFromConfig(opts *BackendOpts) (backend.Backend, error) {
 		s = terraform.NewState()
 	}
 
+	// if we want to force reconfiguration of the backend, we set the backend
+	// state to nil on this copy. This will direct us through the correct
+	// configuration path in the switch statement below.
+	if m.reconfigure {
+		s.Backend = nil
+	}
+
 	// Upon return, we want to set the state we're using in-memory so that
 	// we can access it for commands.
 	m.backendState = nil

command/meta_backend_test.go

@@ -983,6 +983,59 @@ func TestMetaBackend_configuredChange(t *testing.T) {
 	}
 }
 
+// Reconfiguring with an already configured backend.
+// This should ignore the existing backend config, and configure the new
+// backend is if this is the first time.
+func TestMetaBackend_reconfigureChange(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("backend-change-single-to-single"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	// Register the single-state backend
+	backendinit.Set("local-single", backendlocal.TestNewLocalSingle)
+	defer backendinit.Set("local-single", nil)
+
+	// Setup the meta
+	m := testMetaBackend(t, nil)
+
+	// this should not ask for input
+	m.input = false
+
+	// cli flag -reconfigure
+	m.reconfigure = true
+
+	// Get the backend
+	b, err := m.Backend(&BackendOpts{Init: true})
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+
+	// Check the state
+	s, err := b.State(backend.DefaultStateName)
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+	if err := s.RefreshState(); err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+	newState := s.State()
+	if newState != nil || !newState.Empty() {
+		t.Fatal("state should be nil/empty after forced reconfiguration")
+	}
+
+	// verify that the old state is still there
+	s = (&state.LocalState{Path: "local-state.tfstate"})
+	if err := s.RefreshState(); err != nil {
+		t.Fatal(err)
+	}
+	oldState := s.State()
+	if oldState == nil || oldState.Empty() {
+		t.Fatal("original state should be untouched")
+	}
+}
+
 // Changing a configured backend, copying state
 func TestMetaBackend_configuredChangeCopy(t *testing.T) {
 	// Create a temporary working directory that is empty

website/source/docs/commands/init.html.markdown

@@ -49,6 +49,9 @@ The command-line flags are all optional. The list of available flags are:
   for the backend. This can be specified multiple times. Flags specified
   later in the line override those specified earlier if they conflict.
 
+* `-force-copy` -  Suppress prompts about copying state data. This is equivalent
+  to providing a "yes" to all confirmation prompts.
+
 * `-get=true` - Download any modules for this configuration.
 
 * `-input=true` - Ask for input interactively if necessary. If this is false
@@ -60,8 +63,7 @@ The command-line flags are all optional. The list of available flags are:
 
 * `-no-color` - If specified, output won't contain any color.
 
-* `-force-copy` -  Suppress prompts about copying state data. This is equivalent
-  to providing a "yes" to all confirmation prompts.
+* `-reconfigure` - Reconfigure the backend, ignoring any saved configuration.
 
 ## Backend Config