Change how to fall back from remote to local backend

In order to support free organizations, we need a way to load the `remote` backend and then, depending on the used offering/plan, enable or disable remote operations.

In other words, we should be able to dynamically fall back to the `local` backend if needed, after first configuring the `remote` backend.

To make this works we need to change the way this was done previously when the env var `TF_FORCE_LOCAL_BACKEND` was set. The clear difference of course being that the env var would be available on startup, while the used offering/plan is only known after being able to connect to TFE.

backend/init/init.go

@@ -3,7 +3,6 @@
 package init
 
 import (
-	"os"
 	"sync"
 
 	"github.com/hashicorp/terraform/backend"
@@ -48,14 +47,8 @@ func Init(services *disco.Disco) {
 
 	backends = map[string]backend.InitFn{
 		// Enhanced backends.
-		"local": func() backend.Backend { return backendLocal.New() },
-		"remote": func() backend.Backend {
-			b := backendRemote.New(services)
-			if os.Getenv("TF_FORCE_LOCAL_BACKEND") != "" {
-				return backendLocal.NewWithBackend(b)
-			}
-			return b
-		},
+		"local":  func() backend.Backend { return backendLocal.New() },
+		"remote": func() backend.Backend { return backendRemote.New(services) },
 
 		// Remote State backends.
 		"artifactory": func() backend.Backend { return backendArtifactory.New() },

backend/init/init_test.go

@@ -1,11 +1,8 @@
 package init
 
 import (
-	"os"
 	"reflect"
 	"testing"
-
-	backendLocal "github.com/hashicorp/terraform/backend/local"
 )
 
 func TestInit_backend(t *testing.T) {
@@ -44,42 +41,3 @@ func TestInit_backend(t *testing.T) {
 		})
 	}
 }
-
-func TestInit_forceLocalBackend(t *testing.T) {
-	// Initialize the backends map
-	Init(nil)
-
-	enhancedBackends := []struct {
-		Name string
-		Type string
-	}{
-		{"local", "nil"},
-		{"remote", "*remote.Remote"},
-	}
-
-	// Set the TF_FORCE_LOCAL_BACKEND flag so all enhanced backends will
-	// return a local.Local backend with themselves as embedded backend.
-	if err := os.Setenv("TF_FORCE_LOCAL_BACKEND", "1"); err != nil {
-		t.Fatalf("error setting environment variable TF_FORCE_LOCAL_BACKEND: %v", err)
-	}
-	defer os.Unsetenv("TF_FORCE_LOCAL_BACKEND")
-
-	// Make sure we always get the local backend.
-	for _, b := range enhancedBackends {
-		f := Backend(b.Name)
-
-		local, ok := f().(*backendLocal.Local)
-		if !ok {
-			t.Fatalf("expected backend %q to be \"*local.Local\", got: %T", b.Name, f())
-		}
-
-		bType := "nil"
-		if local.Backend != nil {
-			bType = reflect.TypeOf(local.Backend).String()
-		}
-
-		if bType != b.Type {
-			t.Fatalf("expected local.Backend to be %s, got: %s", b.Type, bType)
-		}
-	}
-}

backend/local/backend.go

@@ -250,8 +250,6 @@ func (b *Local) DeleteWorkspace(name string) error {
 }
 
 func (b *Local) StateMgr(name string) (statemgr.Full, error) {
-	statePath, stateOutPath, backupPath := b.StatePaths(name)
-
 	// If we have a backend handling state, delegate to that.
 	if b.Backend != nil {
 		return b.Backend.StateMgr(name)
@@ -265,6 +263,8 @@ func (b *Local) StateMgr(name string) (statemgr.Full, error) {
 		return nil, err
 	}
 
+	statePath, stateOutPath, backupPath := b.StatePaths(name)
+
 	s := statemgr.NewFilesystemBetweenPaths(statePath, stateOutPath)
 	if backupPath != "" {
 		s.SetBackupPath(backupPath)