terraform: test that varaibles from the plan are interpolated in

terraform/terraform.go

@@ -167,7 +167,7 @@ func (t *Terraform) applyWalkFn(
 		return vars, nil
 	}
 
-	return t.genericWalkFn(p.State, p.Diff, cb)
+	return t.genericWalkFn(p.State, p.Diff, p.Vars, cb)
 }
 
 func (t *Terraform) planWalkFn(
@@ -179,7 +179,12 @@ func (t *Terraform) planWalkFn(
 
 	// Write our configuration out
 	result.Config = t.config
-	result.Vars = t.variables
+
+	// Copy the variables
+	result.Vars = make(map[string]string)
+	for k, v := range t.variables {
+		result.Vars[k] = v
+	}
 
 	cb := func(r *Resource) (map[string]string, error) {
 		// Refresh the state so we're working with the latest resource info
@@ -216,19 +221,20 @@ func (t *Terraform) planWalkFn(
 		return vars, nil
 	}
 
-	return t.genericWalkFn(state, nil, cb)
+	return t.genericWalkFn(state, nil, t.variables, cb)
 }
 
 func (t *Terraform) genericWalkFn(
 	state *State,
 	diff *Diff,
+	invars map[string]string,
 	cb genericWalkFunc) depgraph.WalkFunc {
 	var l sync.Mutex
 
 	// Initialize the variables for application
 	vars := make(map[string]string)
-	for k, v := range t.variables {
-		vars[k] = v
+	for k, v := range invars {
+		vars[fmt.Sprintf("var.%s", k)] = v
 	}
 
 	return func(n *depgraph.Noun) error {

terraform/terraform_test.go

@@ -256,6 +256,31 @@ func TestTerraformApply_compute(t *testing.T) {
 	}
 }
 
+func TestTerraformApply_vars(t *testing.T) {
+	tf := testTerraform(t, "apply-vars")
+	tf.variables = map[string]string{"foo": "baz"}
+
+	s := &State{}
+	p, err := tf.Plan(s)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Explicitly set the "foo" variable
+	p.Vars["foo"] = "bar"
+
+	state, err := tf.Apply(p)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(state.String())
+	expected := strings.TrimSpace(testTerraformApplyVarsStr)
+	if actual != expected {
+		t.Fatalf("bad: \n%s", actual)
+	}
+}
+
 func TestTerraformPlan(t *testing.T) {
 	tf := testTerraform(t, "plan-good")
 
@@ -550,6 +575,17 @@ aws_instance.foo:
   id = computed_id
 `
 
+const testTerraformApplyVarsStr = `
+aws_instance.bar:
+  ID = foo
+  type = aws_instance
+  foo = bar
+aws_instance.foo:
+  ID = foo
+  type = aws_instance
+  num = 2
+`
+
 const testTerraformPlanStr = `
 UPDATE: aws_instance.bar
   foo:  "" => "2"

terraform/test-fixtures/apply-vars/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "foo" {
+    num = "2"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${var.foo}"
+}