terraform: multi-variables work with count = 1 [GH-115]

CHANGELOG.md

@@ -13,6 +13,7 @@ IMPROVEMENTS:
 BUG FIXES:
 
   * core: Default variable file "terraform.tfvars" is auto-loaded. [GH-59]
+  * core: Multi-variables (`foo.*.bar`) work even when `count = 1`. [GH-115]
   * providers/cloudflare: Include the proper bins so the cloudflare
       provider is compiled
   * providers/aws: Engine version for RDS now properly set [GH-118]

terraform/context.go

@@ -406,6 +406,13 @@ func (c *Context) computeResourceMultiVariable(
 	var values []string
 	for i := 0; i < cr.Count; i++ {
 		id := fmt.Sprintf("%s.%d", v.ResourceId(), i)
+
+		// If we're dealing with only a single resource, then the
+		// ID doesn't have a trailing index.
+		if cr.Count == 1 {
+			id = v.ResourceId()
+		}
+
 		r, ok := c.state.Resources[id]
 		if !ok {
 			continue

terraform/context_test.go

@@ -1781,6 +1781,29 @@ func TestContextPlan_taint(t *testing.T) {
 	}
 }
 
+func TestContextPlan_varMultiCountOne(t *testing.T) {
+	c := testConfig(t, "plan-var-multi-count-one")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Config: c,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	plan, err := ctx.Plan(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(plan.String())
+	expected := strings.TrimSpace(testTerraformPlanVarMultiCountOneStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func TestContextRefresh(t *testing.T) {
 	p := testProvider("aws")
 	c := testConfig(t, "refresh-basic")

terraform/terraform_test.go

@@ -478,3 +478,19 @@ aws_instance.foo:
   ID = bar
   num = 2
 `
+
+const testTerraformPlanVarMultiCountOneStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => "2"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo
+  num:  "" => "2"
+  type: "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+

terraform/test-fixtures/plan-var-multi-count-one/main.tf

@@ -0,0 +1,9 @@
+resource "aws_instance" "foo" {
+    num = "2"
+
+    count = 1
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.*.num}"
+}