From 1480d0c5b8888f1bd4b274cc1e679f51c87a6b8d Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 15 Feb 2017 16:00:59 -0800
Subject: [PATCH 1/2] backend/local: check for empty config on apply

This prevents Terraform from crashing on apply/destroy with a directory
with no Terraform configuration files. We allow a destroy with no files
but not an apply.
---
 backend/local/backend_apply.go                | 24 +++++++++
 backend/local/backend_apply_test.go           | 54 +++++++++++++++++++
 .../local/test-fixtures/apply-empty/hello.txt |  1 +
 3 files changed, 79 insertions(+)
 create mode 100644 backend/local/test-fixtures/apply-empty/hello.txt

diff --git a/backend/local/backend_apply.go b/backend/local/backend_apply.go
index 466bce468..30cbe0cf6 100644
--- a/backend/local/backend_apply.go
+++ b/backend/local/backend_apply.go
@@ -4,11 +4,13 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"strings"
 
 	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/terraform/backend"
 	clistate "github.com/hashicorp/terraform/command/state"
+	"github.com/hashicorp/terraform/config/module"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -19,6 +21,19 @@ func (b *Local) opApply(
 	runningOp *backend.RunningOperation) {
 	log.Printf("[INFO] backend/local: starting Apply operation")
 
+	// If we have a nil module at this point, then set it to an empty tree
+	// to avoid any potential crashes.
+	if op.Module == nil && !op.Destroy {
+		runningOp.Err = fmt.Errorf(strings.TrimSpace(applyErrNoConfig))
+		return
+	}
+
+	// If we have a nil module at this point, then set it to an empty tree
+	// to avoid any potential crashes.
+	if op.Module == nil {
+		op.Module = module.NewEmptyTree()
+	}
+
 	// Setup our count hook that keeps track of resource changes
 	countHook := new(CountHook)
 	stateHook := new(StateHook)
@@ -165,3 +180,12 @@ func (b *Local) opApply(
 		}
 	}
 }
+
+const applyErrNoConfig = `
+No configuration files found!
+
+Apply requires configuration to be present. Applying without a configuration
+would mark everything for destruction, which is normally not what is desired.
+If you would like to destroy everything, please run 'terraform destroy' instead
+which does not require any configuration files.
+`
diff --git a/backend/local/backend_apply_test.go b/backend/local/backend_apply_test.go
index 7424faa6b..c761d1538 100644
--- a/backend/local/backend_apply_test.go
+++ b/backend/local/backend_apply_test.go
@@ -3,6 +3,7 @@ package local
 import (
 	"context"
 	"fmt"
+	"os"
 	"sync"
 	"testing"
 
@@ -50,6 +51,59 @@ test_instance.foo:
 	`)
 }
 
+func TestLocal_applyEmptyDir(t *testing.T) {
+	b := TestLocal(t)
+	p := TestLocalProvider(t, b, "test")
+
+	p.ApplyReturn = &terraform.InstanceState{ID: "yes"}
+
+	op := testOperationApply()
+	op.Module = nil
+
+	run, err := b.Operation(context.Background(), op)
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+	<-run.Done()
+	if run.Err == nil {
+		t.Fatal("should error")
+	}
+
+	if p.ApplyCalled {
+		t.Fatal("apply should not be called")
+	}
+
+	if _, err := os.Stat(b.StateOutPath); err == nil {
+		t.Fatal("should not exist")
+	}
+}
+
+func TestLocal_applyEmptyDirDestroy(t *testing.T) {
+	b := TestLocal(t)
+	p := TestLocalProvider(t, b, "test")
+
+	p.ApplyReturn = nil
+
+	op := testOperationApply()
+	op.Module = nil
+	op.Destroy = true
+
+	run, err := b.Operation(context.Background(), op)
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+	<-run.Done()
+	if run.Err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if p.ApplyCalled {
+		t.Fatal("apply should not be called")
+	}
+
+	checkState(t, b.StateOutPath, `<no state>`)
+}
+
 func TestLocal_applyError(t *testing.T) {
 	b := TestLocal(t)
 	p := TestLocalProvider(t, b, "test")
diff --git a/backend/local/test-fixtures/apply-empty/hello.txt b/backend/local/test-fixtures/apply-empty/hello.txt
new file mode 100644
index 000000000..7dcfcbb4a
--- /dev/null
+++ b/backend/local/test-fixtures/apply-empty/hello.txt
@@ -0,0 +1 @@
+This is an empty dir

From d443bf1b565cdb139ed00354d821d0df5bb8ca70 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Thu, 16 Feb 2017 10:56:39 -0800
Subject: [PATCH 2/2] backend/local: allow nil modules (no config) if executing
 a plan

---
 backend/local/backend_apply.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/backend/local/backend_apply.go b/backend/local/backend_apply.go
index 30cbe0cf6..6b80aac34 100644
--- a/backend/local/backend_apply.go
+++ b/backend/local/backend_apply.go
@@ -23,7 +23,7 @@ func (b *Local) opApply(
 
 	// If we have a nil module at this point, then set it to an empty tree
 	// to avoid any potential crashes.
-	if op.Module == nil && !op.Destroy {
+	if op.Plan == nil && op.Module == nil && !op.Destroy {
 		runningOp.Err = fmt.Errorf(strings.TrimSpace(applyErrNoConfig))
 		return
 	}