terraform: inner-count dependencies work [GH-1540]

terraform/graph_config_node.go

@@ -279,6 +279,25 @@ func (n *GraphNodeConfigResource) DependentOn() []string {
 	return result
 }
 
+// VarWalk calls a callback for all the variables that this resource
+// depends on.
+func (n *GraphNodeConfigResource) VarWalk(fn func(config.InterpolatedVariable)) {
+	for _, v := range n.Resource.RawCount.Variables {
+		fn(v)
+	}
+	for _, v := range n.Resource.RawConfig.Variables {
+		fn(v)
+	}
+	for _, p := range n.Resource.Provisioners {
+		for _, v := range p.ConnInfo.Variables {
+			fn(v)
+		}
+		for _, v := range p.RawConfig.Variables {
+			fn(v)
+		}
+	}
+}
+
 func (n *GraphNodeConfigResource) Name() string {
 	result := n.Resource.Id()
 	switch n.DestroyMode {

terraform/test-fixtures/transform-resource-count-basic/main.tf

@@ -1,4 +1,3 @@
 resource "aws_instance" "foo" {
     count = 3
-    value = "${aws_instance.foo.0.value}"
 }

terraform/test-fixtures/transform-resource-count-deps/main.tf

@@ -0,0 +1,8 @@
+resource "aws_instance" "foo" {
+    count = 2
+
+    provisioner "local-exec" {
+        command = "echo ${aws_instance.foo.0.id}"
+        other = "echo ${aws_instance.foo.id}"
+    }
+}

terraform/transform_resource.go

@@ -134,8 +134,34 @@ func (n *graphNodeExpandedResource) DependableName() []string {
 
 // GraphNodeDependent impl.
 func (n *graphNodeExpandedResource) DependentOn() []string {
-	config := &GraphNodeConfigResource{Resource: n.Resource}
-	return config.DependentOn()
+	configNode := &GraphNodeConfigResource{Resource: n.Resource}
+	result := configNode.DependentOn()
+
+	// Walk the variables to find any count-specific variables we depend on.
+	configNode.VarWalk(func(v config.InterpolatedVariable) {
+		rv, ok := v.(*config.ResourceVariable)
+		if !ok {
+			return
+		}
+
+		// We only want ourselves
+		if rv.ResourceId() != n.Resource.Id() {
+			return
+		}
+
+		// If this isn't a multi-access (which shouldn't be allowed but
+		// is verified elsewhere), then we depend on the specific count
+		// of this resource, ignoring ourself (which again should be
+		// validated elsewhere).
+		if rv.Index > -1 {
+			id := fmt.Sprintf("%s.%d", rv.ResourceId(), rv.Index)
+			if id != n.stateId() && id != n.stateId()+".0" {
+				result = append(result, id)
+			}
+		}
+	})
+
+	return result
 }
 
 // GraphNodeProviderConsumer

terraform/transform_resource_test.go

@@ -37,11 +37,33 @@ func TestResourceCountTransformer_countNegative(t *testing.T) {
 	}
 }
 
+func TestResourceCountTransformer_deps(t *testing.T) {
+	cfg := testModule(t, "transform-resource-count-deps").Config()
+	resource := cfg.Resources[0]
+
+	g := Graph{Path: RootModulePath}
+	{
+		tf := &ResourceCountTransformer{Resource: resource}
+		if err := tf.Transform(&g); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testResourceCountTransformDepsStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 const testResourceCountTransformStr = `
 aws_instance.foo #0
-  aws_instance.foo #2
 aws_instance.foo #1
-  aws_instance.foo #2
 aws_instance.foo #2
-  aws_instance.foo #2
+`
+
+const testResourceCountTransformDepsStr = `
+aws_instance.foo #0
+aws_instance.foo #1
+  aws_instance.foo #0
 `