backend/local: do not use backend operation variables

backend/backend.go

@@ -143,7 +143,11 @@ type Operation struct {
 	ModuleDepth  int
 	Parallelism  int
 	Targets      []string
-	Variables    map[string]interface{}
+
+	// Variables should only contain any variables passed as command
+	// arguments and not any variables read from the terraform.tfvars
+	// or *.auto.tfvars files.
+	Variables map[string]interface{}
 
 	// Input/output/control options.
 	UIIn  terraform.UIInput

backend/local/backend_apply_test.go

@@ -114,6 +114,40 @@ func TestLocal_applyEmptyDirDestroy(t *testing.T) {
 	checkState(t, b.StateOutPath, `<no state>`)
 }
 
+func TestLocal_applyWithVariables(t *testing.T) {
+	b, cleanup := TestLocal(t)
+	defer cleanup()
+	p := TestLocalProvider(t, b, "test")
+
+	p.ApplyReturn = &terraform.InstanceState{ID: "yes"}
+
+	mod, modCleanup := module.TestTree(t, "./test-fixtures/apply-vars")
+	defer modCleanup()
+
+	op := testOperationApply()
+	op.Module = mod
+	op.Variables = map[string]interface{}{"cli": "var"}
+
+	// Set some variables that would have been read from
+	// any terraform.tfvars or *.auto.tfvars files.
+	b.ContextOpts.Variables = map[string]interface{}{"foo": "bar"}
+
+	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", run.Err)
+	}
+
+	checkState(t, b.StateOutPath, `
+test_instance.foo:
+  ID = yes
+  provider = provider.test
+	`)
+}
+
 func TestLocal_applyError(t *testing.T) {
 	b, cleanup := TestLocal(t)
 	defer cleanup()

backend/local/backend_local.go

@@ -55,9 +55,6 @@ func (b *Local) context(op *backend.Operation) (*terraform.Context, state.State,
 	opts.Module = op.Module
 	opts.Targets = op.Targets
 	opts.UIInput = op.UIIn
-	if op.Variables != nil {
-		opts.Variables = op.Variables
-	}
 
 	// Load our state
 	// By the time we get here, the backend creation code in "command" took

backend/local/backend_plan_test.go

@@ -158,6 +158,37 @@ func TestLocal_planRefreshFalse(t *testing.T) {
 	}
 }
 
+func TestLocal_planWithVariables(t *testing.T) {
+	b, cleanup := TestLocal(t)
+	defer cleanup()
+	TestLocalProvider(t, b, "test")
+
+	mod, modCleanup := module.TestTree(t, "./test-fixtures/plan-vars")
+	defer modCleanup()
+
+	op := testOperationPlan()
+	op.Module = mod
+	op.PlanRefresh = true
+	op.Variables = map[string]interface{}{"cli": "var"}
+
+	// Set some variables that would have been read from
+	// any terraform.tfvars or *.auto.tfvars files.
+	b.ContextOpts.Variables = map[string]interface{}{"foo": "bar"}
+
+	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", run.Err)
+	}
+
+	if run.PlanEmpty {
+		t.Fatal("plan should not be empty")
+	}
+}
+
 func TestLocal_planDestroy(t *testing.T) {
 	b, cleanup := TestLocal(t)
 	defer cleanup()

backend/local/test-fixtures/apply-vars/main.tf

@@ -0,0 +1,5 @@
+variable "foo" {}
+
+resource "test_instance" "foo" {
+    foo = "${var.foo}"
+}

backend/local/test-fixtures/plan-vars/main.tf

@@ -0,0 +1,11 @@
+variable "foo" {}
+
+resource "test_instance" "foo" {
+    foo = "${var.foo}"
+
+    # This is here because at some point it caused a test failure
+    network_interface {
+      device_index = 0
+      description = "Main network interface"
+    }
+}