update local.Local to match the latest Backend

Update the methods, remove the handling of "current", and make tests
pass.

backend/backend.go

@@ -123,6 +123,9 @@ type Operation struct {
 	// If LockState is true, the Operation must Lock any
 	// state.Lockers for its duration, and Unlock when complete.
 	LockState bool
+
+	// Environment is the named state that should be loaded from the Backend.
+	Environment string
 }
 
 // RunningOperation is the result of starting an operation.

backend/local/backend.go

@@ -53,8 +53,10 @@ type Local struct {
 	StateOutPath    string
 	StateBackupPath string
 
-	// we only want to create a single instance of the local state
-	state state.State
+	// We only want to create a single instance of a local state, so store them
+	// here as they're loaded.
+	states map[string]state.State
+
 	// Terraform context. Many of these will be overridden or merged by
 	// Operation. See Operation for more details.
 	ContextOpts *terraform.ContextOpts
@@ -78,10 +80,6 @@ type Local struct {
 	schema *schema.Backend
 	opLock sync.Mutex
 	once   sync.Once
-
-	// workingDir is where the State* paths should be relative to.
-	// This is currently only used for tests.
-	workingDir string
 }
 
 func (b *Local) Input(
@@ -118,54 +116,35 @@ func (b *Local) Configure(c *terraform.ResourceConfig) error {
 	return f(c)
 }
 
-func (b *Local) States() ([]string, string, error) {
+func (b *Local) States() ([]string, error) {
 	// If we have a backend handling state, defer to that.
 	if b.Backend != nil {
-		if b, ok := b.Backend.(backend.MultiState); ok {
-			return b.States()
-		} else {
-			return nil, "", ErrEnvNotSupported
-		}
+		return b.Backend.States()
 	}
 
 	// the listing always start with "default"
 	envs := []string{backend.DefaultStateName}
 
-	current, err := b.currentStateName()
-	if err != nil {
-		return nil, "", err
-	}
-
-	entries, err := ioutil.ReadDir(filepath.Join(b.workingDir, DefaultEnvDir))
+	entries, err := ioutil.ReadDir(DefaultEnvDir)
 	// no error if there's no envs configured
 	if os.IsNotExist(err) {
-		return envs, backend.DefaultStateName, nil
+		return envs, nil
 	}
 	if err != nil {
-		return nil, "", err
+		return nil, err
 	}
 
-	currentExists := false
 	var listed []string
 	for _, entry := range entries {
 		if entry.IsDir() {
-			name := filepath.Base(entry.Name())
-			if name == current {
-				currentExists = true
-			}
-			listed = append(listed, name)
+			listed = append(listed, filepath.Base(entry.Name()))
 		}
 	}
 
-	// current was out of sync for some reason, so return defualt
-	if !currentExists {
-		current = backend.DefaultStateName
-	}
-
 	sort.Strings(listed)
 	envs = append(envs, listed...)
 
-	return envs, current, nil
+	return envs, nil
 }
 
 // DeleteState removes a named state.
@@ -173,11 +152,7 @@ func (b *Local) States() ([]string, string, error) {
 func (b *Local) DeleteState(name string) error {
 	// If we have a backend handling state, defer to that.
 	if b.Backend != nil {
-		if b, ok := b.Backend.(backend.MultiState); ok {
-			return b.DeleteState(name)
-		} else {
-			return ErrEnvNotSupported
-		}
+		return b.Backend.DeleteState(name)
 	}
 
 	if name == "" {
@@ -188,91 +163,25 @@ func (b *Local) DeleteState(name string) error {
 		return errors.New("cannot delete default state")
 	}
 
-	_, current, err := b.States()
-	if err != nil {
-		return err
-	}
-
-	// if we're deleting the current state, we change back to the default
-	if name == current {
-		if err := b.ChangeState(backend.DefaultStateName); err != nil {
-			return err
-		}
-	}
-
-	return os.RemoveAll(filepath.Join(b.workingDir, DefaultEnvDir, name))
+	delete(b.states, name)
+	return os.RemoveAll(filepath.Join(DefaultEnvDir, name))
 }
 
-// Change to the named state, creating it if it doesn't exist.
-func (b *Local) ChangeState(name string) error {
+func (b *Local) State(name string) (state.State, error) {
 	// If we have a backend handling state, defer to that.
 	if b.Backend != nil {
-		if b, ok := b.Backend.(backend.MultiState); ok {
-			return b.ChangeState(name)
-		} else {
-			return ErrEnvNotSupported
-		}
+		return b.Backend.State(name)
 	}
 
-	name = strings.TrimSpace(name)
-	if name == "" {
-		return errors.New("state name cannot be empty")
+	if s, ok := b.states[name]; ok {
+		return s, nil
 	}
 
-	envs, current, err := b.States()
-	if err != nil {
-		return err
+	if err := b.createState(name); err != nil {
+		return nil, err
 	}
 
-	if name == current {
-		return nil
-	}
-
-	exists := false
-	for _, env := range envs {
-		if env == name {
-			exists = true
-			break
-		}
-	}
-
-	if !exists {
-		if err := b.createState(name); err != nil {
-			return err
-		}
-	}
-
-	err = os.MkdirAll(filepath.Join(b.workingDir, DefaultDataDir), 0755)
-	if err != nil {
-		return err
-	}
-
-	err = ioutil.WriteFile(
-		filepath.Join(b.workingDir, DefaultDataDir, DefaultEnvFile),
-		[]byte(name),
-		0644,
-	)
-	if err != nil {
-		return err
-	}
-
-	// remove the current state so it's reloaded on the next call to State
-	b.state = nil
-
-	return nil
-}
-
-func (b *Local) State() (state.State, error) {
-	// If we have a backend handling state, defer to that.
-	if b.Backend != nil {
-		return b.Backend.State()
-	}
-
-	if b.state != nil {
-		return b.state, nil
-	}
-
-	statePath, stateOutPath, backupPath, err := b.StatePaths()
+	statePath, stateOutPath, backupPath, err := b.StatePaths(name)
 	if err != nil {
 		return nil, err
 	}
@@ -291,7 +200,10 @@ func (b *Local) State() (state.State, error) {
 		}
 	}
 
-	b.state = s
+	if b.states == nil {
+		b.states = map[string]state.State{}
+	}
+	b.states[name] = s
 	return s, nil
 }
 
@@ -385,20 +297,24 @@ func (b *Local) schemaConfigure(ctx context.Context) error {
 }
 
 // StatePaths returns the StatePath, StateOutPath, and StateBackupPath as
-// configured by the current environment. If backups are disabled,
-// StateBackupPath will be an empty string.
-func (b *Local) StatePaths() (string, string, string, error) {
+// configured from the CLI.
+func (b *Local) StatePaths(name string) (string, string, string, error) {
 	statePath := b.StatePath
 	stateOutPath := b.StateOutPath
 	backupPath := b.StateBackupPath
 
-	if statePath == "" {
-		path, err := b.statePath()
-		if err != nil {
-			return "", "", "", err
-		}
-		statePath = path
+	if name == "" {
+		name = backend.DefaultStateName
 	}
+
+	if name == backend.DefaultStateName {
+		if statePath == "" {
+			statePath = name
+		}
+	} else {
+		statePath = filepath.Join(DefaultEnvDir, name, DefaultStateFilename)
+	}
+
 	if stateOutPath == "" {
 		stateOutPath = statePath
 	}
@@ -413,33 +329,21 @@ func (b *Local) StatePaths() (string, string, string, error) {
 	return statePath, stateOutPath, backupPath, nil
 }
 
-func (b *Local) statePath() (string, error) {
-	_, current, err := b.States()
-	if err != nil {
-		return "", err
-	}
-	path := DefaultStateFilename
-
-	if current != backend.DefaultStateName && current != "" {
-		path = filepath.Join(b.workingDir, DefaultEnvDir, current, DefaultStateFilename)
-	}
-	return path, nil
-}
-
+// this only ensures that the named directory exists
 func (b *Local) createState(name string) error {
-	stateNames, _, err := b.States()
-	if err != nil {
-		return err
+	if name == backend.DefaultStateName {
+		return nil
 	}
 
-	for _, n := range stateNames {
-		if name == n {
-			// state exists, nothing to do
-			return nil
-		}
+	stateDir := filepath.Join(DefaultEnvDir, name)
+	s, err := os.Stat(stateDir)
+	if err == nil && s.IsDir() {
+		// no need to check for os.IsNotExist, since that is covered by os.MkdirAll
+		// which will catch the other possible errors as well.
+		return nil
 	}
 
-	err = os.MkdirAll(filepath.Join(b.workingDir, DefaultEnvDir, name), 0755)
+	err = os.MkdirAll(stateDir, 0755)
 	if err != nil {
 		return err
 	}
@@ -451,7 +355,7 @@ func (b *Local) createState(name string) error {
 // configuration files.
 // If there are no configured environments, currentStateName returns "default"
 func (b *Local) currentStateName() (string, error) {
-	contents, err := ioutil.ReadFile(filepath.Join(b.workingDir, DefaultDataDir, DefaultEnvFile))
+	contents, err := ioutil.ReadFile(filepath.Join(DefaultDataDir, DefaultEnvFile))
 	if os.IsNotExist(err) {
 		return backend.DefaultStateName, nil
 	}

backend/local/backend_local.go

@@ -23,7 +23,7 @@ func (b *Local) Context(op *backend.Operation) (*terraform.Context, state.State,
 
 func (b *Local) context(op *backend.Operation) (*terraform.Context, state.State, error) {
 	// Get the state.
-	s, err := b.State()
+	s, err := b.State(op.Environment)
 	if err != nil {
 		return nil, nil, errwrap.Wrapf("Error loading state: {{err}}", err)
 	}

backend/local/backend_test.go

@@ -1,15 +1,15 @@
 package local
 
 import (
-	"fmt"
+	"errors"
 	"io/ioutil"
 	"os"
-	"path/filepath"
 	"reflect"
 	"strings"
 	"testing"
 
 	"github.com/hashicorp/terraform/backend"
+	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/terraform"
 )
 
@@ -17,7 +17,6 @@ func TestLocal_impl(t *testing.T) {
 	var _ backend.Enhanced = new(Local)
 	var _ backend.Local = new(Local)
 	var _ backend.CLI = new(Local)
-	var _ backend.MultiState = new(Local)
 }
 
 func checkState(t *testing.T, path, expected string) {
@@ -46,31 +45,24 @@ func TestLocal_addAndRemoveStates(t *testing.T) {
 	expectedStates := []string{dflt}
 
 	b := &Local{}
-	states, current, err := b.States()
+	states, err := b.States()
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	if current != dflt {
-		t.Fatalf("expected %q, got %q", dflt, current)
-	}
-
 	if !reflect.DeepEqual(states, expectedStates) {
 		t.Fatalf("expected []string{%q}, got %q", dflt, states)
 	}
 
 	expectedA := "test_A"
-	if err := b.ChangeState(expectedA); err != nil {
+	if _, err := b.State(expectedA); err != nil {
 		t.Fatal(err)
 	}
 
-	states, current, err = b.States()
+	states, err = b.States()
 	if err != nil {
 		t.Fatal(err)
 	}
-	if current != expectedA {
-		t.Fatalf("expected %q, got %q", expectedA, current)
-	}
 
 	expectedStates = append(expectedStates, expectedA)
 	if !reflect.DeepEqual(states, expectedStates) {
@@ -78,17 +70,14 @@ func TestLocal_addAndRemoveStates(t *testing.T) {
 	}
 
 	expectedB := "test_B"
-	if err := b.ChangeState(expectedB); err != nil {
+	if _, err := b.State(expectedB); err != nil {
 		t.Fatal(err)
 	}
 
-	states, current, err = b.States()
+	states, err = b.States()
 	if err != nil {
 		t.Fatal(err)
 	}
-	if current != expectedB {
-		t.Fatalf("expected %q, got %q", expectedB, current)
-	}
 
 	expectedStates = append(expectedStates, expectedB)
 	if !reflect.DeepEqual(states, expectedStates) {
@@ -99,13 +88,10 @@ func TestLocal_addAndRemoveStates(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	states, current, err = b.States()
+	states, err = b.States()
 	if err != nil {
 		t.Fatal(err)
 	}
-	if current != expectedB {
-		t.Fatalf("expected %q, got %q", dflt, current)
-	}
 
 	expectedStates = []string{dflt, expectedB}
 	if !reflect.DeepEqual(states, expectedStates) {
@@ -116,13 +102,10 @@ func TestLocal_addAndRemoveStates(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	states, current, err = b.States()
+	states, err = b.States()
 	if err != nil {
 		t.Fatal(err)
 	}
-	if current != dflt {
-		t.Fatalf("expected %q, got %q", dflt, current)
-	}
 
 	expectedStates = []string{dflt}
 	if !reflect.DeepEqual(states, expectedStates) {
@@ -134,97 +117,45 @@ func TestLocal_addAndRemoveStates(t *testing.T) {
 	}
 }
 
-// verify the behavior with a backend that doesn't support multiple states
-func TestLocal_noMultiStateBackend(t *testing.T) {
-	type noMultiState struct {
-		backend.Backend
-	}
+// a local backend which return sentinel errors for NamedState methods to
+// verify it's being called.
+type testDelegateBackend struct {
+	*Local
+}
 
-	b := &Local{
-		Backend: &noMultiState{},
-	}
+var errTestDelegateState = errors.New("State called")
+var errTestDelegateStates = errors.New("States called")
+var errTestDelegateDeleteState = errors.New("Delete called")
 
-	_, _, err := b.States()
-	if err != ErrEnvNotSupported {
-		t.Fatal("backend does not support environments.", err)
-	}
+func (b *testDelegateBackend) State(name string) (state.State, error) {
+	return nil, errTestDelegateState
+}
 
-	err = b.ChangeState("test")
-	if err != ErrEnvNotSupported {
-		t.Fatal("backend does not support environments.", err)
-	}
+func (b *testDelegateBackend) States() ([]string, error) {
+	return nil, errTestDelegateStates
+}
 
-	err = b.ChangeState("test")
-	if err != ErrEnvNotSupported {
-		t.Fatal("backend does not support environments.", err)
-	}
+func (b *testDelegateBackend) DeleteState(name string) error {
+	return errTestDelegateDeleteState
 }
 
 // verify that the MultiState methods are dispatched to the correct Backend.
 func TestLocal_multiStateBackend(t *testing.T) {
-	defer testTmpDir(t)()
-
-	dflt := backend.DefaultStateName
-	expectedStates := []string{dflt}
-
-	// make a second tmp dir for the sub-Backend.
-	// we verify the corret backend was called by checking the paths.
-	tmp, err := ioutil.TempDir("", "tf")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(tmp)
-
-	fmt.Println("second tmp:", tmp)
-
+	// assign a separate backend where we can read the state
 	b := &Local{
-		Backend: &Local{
-			workingDir: tmp,
-		},
+		Backend: &testDelegateBackend{},
 	}
 
-	testA := "test_A"
-	if err := b.ChangeState(testA); err != nil {
-		t.Fatal(err)
+	if _, err := b.State("test"); err != errTestDelegateState {
+		t.Fatal("expected errTestDelegateState, got:", err)
 	}
 
-	states, current, err := b.States()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if current != testA {
-		t.Fatalf("expected %q, got %q", testA, current)
+	if _, err := b.States(); err != errTestDelegateStates {
+		t.Fatal("expected errTestDelegateStates, got:", err)
 	}
 
-	expectedStates = append(expectedStates, testA)
-	if !reflect.DeepEqual(states, expectedStates) {
-		t.Fatalf("expected %q, got %q", expectedStates, states)
-	}
-
-	// verify that no environment paths were created for the top-level Backend
-	if _, err := os.Stat(DefaultDataDir); !os.IsNotExist(err) {
-		t.Fatal("remote state operations should not have written local files")
-	}
-
-	if _, err := os.Stat(filepath.Join(DefaultEnvDir, testA)); !os.IsNotExist(err) {
-		t.Fatal("remote state operations should not have written local files")
-	}
-
-	// remove the new state
-	if err := b.DeleteState(testA); err != nil {
-		t.Fatal(err)
-	}
-
-	states, current, err = b.States()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if current != dflt {
-		t.Fatalf("expected %q, got %q", dflt, current)
-	}
-
-	if !reflect.DeepEqual(states, expectedStates[:1]) {
-		t.Fatalf("expected %q, got %q", expectedStates, states)
+	if err := b.DeleteState("test"); err != errTestDelegateDeleteState {
+		t.Fatal("expected errTestDelegateDeleteState, got:", err)
 	}
 
 }