command: deal with plan states

command/meta.go

@@ -5,7 +5,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"log"
 	"os"
 	"path/filepath"
 
@@ -41,11 +40,6 @@ type Meta struct {
 	color bool
 	oldUi cli.Ui
 
-	// useRemoteState is enabled if we are using remote state storage
-	// This is set when the context is loaded if we read from a remote
-	// enabled state file.
-	useRemoteState bool
-
 	// statePath is the path to the state file. If this is empty, then
 	// no state will be loaded. It is also okay for this to be a path to
 	// a file that doesn't exist; it is assumed that this means that there
@@ -101,14 +95,16 @@ func (m *Meta) Context(copts contextOpts) (*terraform.Context, bool, error) {
 		plan, err := terraform.ReadPlan(f)
 		f.Close()
 		if err == nil {
-			// Check if remote state is enabled, but do not refresh.
-			// Since a plan is supposed to lock-in the changes, we do not
-			// attempt a state refresh.
-			if plan != nil && plan.State != nil && plan.State.Remote != nil && plan.State.Remote.Type != "" {
-				log.Printf("[INFO] Enabling remote state from plan")
-				m.useRemoteState = true
+			// Setup our state
+			state, statePath, err := StateFromPlan(m.statePath, plan)
+			if err != nil {
+				return nil, false, fmt.Errorf("Error loading plan: %s", err)
 			}
 
+			// Set our state
+			m.state = state
+			m.stateOutPath = statePath
+
 			if len(m.variables) > 0 {
 				return nil, false, fmt.Errorf(
 					"You can't set variables with the '-var' or '-var-file' flag\n" +

command/state.go

@@ -8,6 +8,7 @@ import (
 	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/state/remote"
+	"github.com/hashicorp/terraform/terraform"
 )
 
 // State returns the proper state.State implementation to represent the
@@ -24,7 +25,7 @@ func State(localPath string) (state.State, string, error) {
 	remoteCachePath := filepath.Join(DefaultDataDir, DefaultStateFilename)
 	if _, err := os.Stat(remoteCachePath); err == nil {
 		// We have a remote state, initialize that.
-		result, err = remoteState(remoteCachePath)
+		result, err = remoteStateFromPath(remoteCachePath)
 		if err != nil {
 			return nil, "", err
 		}
@@ -62,29 +63,65 @@ func State(localPath string) (state.State, string, error) {
 		resultPath = localPath
 	}
 
+	// If we have a result, make sure to back it up
+	if result != nil {
+		result = &state.BackupState{
+			Real: result,
+			Path: resultPath + DefaultBackupExtention,
+		}
+	}
+
 	// Return whatever state we have
 	return result, resultPath, nil
 }
 
-func remoteState(path string) (state.State, error) {
-	// First create the local state for the path
-	local := &state.LocalState{Path: path}
-	if err := local.RefreshState(); err != nil {
-		return nil, err
-	}
-	localState := local.State()
+// StateFromPlan gets our state from the plan.
+func StateFromPlan(
+	localPath string, plan *terraform.Plan) (state.State, string, error) {
+	var result state.State
+	resultPath := localPath
+	if plan != nil && plan.State != nil &&
+		plan.State.Remote != nil && plan.State.Remote.Type != "" {
+		var err error
 
+		// It looks like we have a remote state in the plan, so
+		// we have to initialize that.
+		resultPath = filepath.Join(DefaultDataDir, DefaultStateFilename)
+		result, err = remoteState(plan.State, resultPath, false)
+		if err != nil {
+			return nil, "", err
+		}
+	}
+
+	if result == nil {
+		local := &state.LocalState{Path: resultPath}
+		local.SetState(plan.State)
+		result = local
+	}
+
+	// If we have a result, make sure to back it up
+	result = &state.BackupState{
+		Real: result,
+		Path: resultPath + DefaultBackupExtention,
+	}
+
+	return result, resultPath, nil
+}
+
+func remoteState(
+	local *terraform.State,
+	localPath string, refresh bool) (state.State, error) {
 	// If there is no remote settings, it is an error
-	if localState.Remote == nil {
+	if local.Remote == nil {
 		return nil, fmt.Errorf("Remote state cache has no remote info")
 	}
 
 	// Initialize the remote client based on the local state
-	client, err := remote.NewClient(localState.Remote.Type, localState.Remote.Config)
+	client, err := remote.NewClient(local.Remote.Type, local.Remote.Config)
 	if err != nil {
 		return nil, errwrap.Wrapf(fmt.Sprintf(
 			"Error initializing remote driver '%s': {{err}}",
-			localState.Remote.Type), err)
+			local.Remote.Type), err)
 	}
 
 	// Create the remote client
@@ -92,30 +129,46 @@ func remoteState(path string) (state.State, error) {
 
 	// Create the cached client
 	cache := &state.CacheState{
-		Cache:   local,
+		Cache:   &state.LocalState{Path: localPath},
 		Durable: durable,
 	}
 
-	// Refresh the cache
-	if err := cache.RefreshState(); err != nil {
-		return nil, errwrap.Wrapf(
-			"Error reloading remote state: {{err}}", err)
-	}
-	switch cache.RefreshResult() {
-	case state.CacheRefreshNoop:
-	case state.CacheRefreshInit:
-	case state.CacheRefreshLocalNewer:
-	case state.CacheRefreshUpdateLocal:
-		// Write our local state out to the durable storage to start.
-		if err := cache.WriteState(localState); err != nil {
-			return nil, errwrap.Wrapf("Error preparing remote state: {{err}}", err)
+	if refresh {
+		// Refresh the cache
+		if err := cache.RefreshState(); err != nil {
+			return nil, errwrap.Wrapf(
+				"Error reloading remote state: {{err}}", err)
 		}
-		if err := cache.PersistState(); err != nil {
-			return nil, errwrap.Wrapf("Error preparing remote state: {{err}}", err)
+		switch cache.RefreshResult() {
+		case state.CacheRefreshNoop:
+		case state.CacheRefreshInit:
+		case state.CacheRefreshLocalNewer:
+		case state.CacheRefreshUpdateLocal:
+			// Write our local state out to the durable storage to start.
+			if err := cache.WriteState(local); err != nil {
+				return nil, errwrap.Wrapf(
+					"Error preparing remote state: {{err}}", err)
+			}
+			if err := cache.PersistState(); err != nil {
+				return nil, errwrap.Wrapf(
+					"Error preparing remote state: {{err}}", err)
+			}
+		default:
+			return nil, errwrap.Wrapf(
+				"Error initilizing remote state: {{err}}", err)
 		}
-	default:
-		return nil, errwrap.Wrapf("Error initilizing remote state: {{err}}", err)
 	}
 
 	return cache, nil
 }
+
+func remoteStateFromPath(path string) (state.State, error) {
+	// First create the local state for the path
+	local := &state.LocalState{Path: path}
+	if err := local.RefreshState(); err != nil {
+		return nil, err
+	}
+	localState := local.State()
+
+	return remoteState(localState, path, true)
+}

state/local.go

@@ -18,6 +18,11 @@ type LocalState struct {
 	written bool
 }
 
+// SetState will force a specific state in-memory for this local state.
+func (s *LocalState) SetState(state *terraform.State) {
+	s.state = state
+}
+
 // StateReader impl.
 func (s *LocalState) State() *terraform.State {
 	return s.state
@@ -34,6 +39,16 @@ func (s *LocalState) WriteState(state *terraform.State) error {
 		path = s.Path
 	}
 
+	// If we don't have any state, we actually delete the file if it exists
+	if state == nil {
+		err := os.Remove(path)
+		if err != nil && os.IsNotExist(err) {
+			return nil
+		}
+
+		return err
+	}
+
 	f, err := os.Create(path)
 	if err != nil {
 		return err