core: graph nodes and edges for local values

A local value is similar to an output in that it exists only within state
and just always evaluates its value as best it can with the current state.
Therefore it has a single graph node type for all walks, which will
deal with that evaluation operation.

terraform/graph_builder_plan.go

@@ -74,6 +74,9 @@ func (b *PlanGraphBuilder) Steps() []GraphTransformer {
 			Module:   b.Module,
 		},
 
+		// Add the local values
+		&LocalTransformer{Module: b.Module},
+
 		// Add the outputs
 		&OutputTransformer{Module: b.Module},
 

terraform/graph_builder_plan_test.go

@@ -61,16 +61,22 @@ aws_load_balancer.weblb
   provider.aws
 aws_security_group.firewall
   provider.aws
+local.instance_id
+  aws_instance.web
 meta.count-boundary (count boundary fixup)
   aws_instance.web
   aws_load_balancer.weblb
   aws_security_group.firewall
+  local.instance_id
   openstack_floating_ip.random
+  output.instance_id
   provider.aws
   provider.openstack
   var.foo
 openstack_floating_ip.random
   provider.openstack
+output.instance_id
+  local.instance_id
 provider.aws
   openstack_floating_ip.random
 provider.aws (close)

terraform/graph_builder_refresh.go

@@ -133,6 +133,9 @@ func (b *RefreshGraphBuilder) Steps() []GraphTransformer {
 		&ParentProviderTransformer{},
 		&AttachProviderConfigTransformer{Module: b.Module},
 
+		// Add the local values
+		&LocalTransformer{Module: b.Module},
+
 		// Add the outputs
 		&OutputTransformer{Module: b.Module},
 

terraform/node_local.go

@@ -0,0 +1,80 @@
+package terraform
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/hashicorp/terraform/config"
+)
+
+// NodeLocal represents a named local value in a particular module.
+//
+// Local value nodes only have one operation, common to all walk types:
+// evaluate the result and place it in state.
+type NodeLocal struct {
+	PathValue []string
+	Config    *config.Local
+}
+
+func (n *NodeLocal) Name() string {
+	result := fmt.Sprintf("local.%s", n.Config.Name)
+	if len(n.PathValue) > 1 {
+		result = fmt.Sprintf("%s.%s", modulePrefixStr(n.PathValue), result)
+	}
+
+	return result
+}
+
+// GraphNodeSubPath
+func (n *NodeLocal) Path() []string {
+	return n.PathValue
+}
+
+// RemovableIfNotTargeted
+func (n *NodeLocal) RemoveIfNotTargeted() bool {
+	return true
+}
+
+// GraphNodeReferenceable
+func (n *NodeLocal) ReferenceableName() []string {
+	name := fmt.Sprintf("local.%s", n.Config.Name)
+	return []string{name}
+}
+
+// GraphNodeReferencer
+func (n *NodeLocal) References() []string {
+	var result []string
+	result = append(result, ReferencesFromConfig(n.Config.RawConfig)...)
+	for _, v := range result {
+		split := strings.Split(v, "/")
+		for i, s := range split {
+			split[i] = s + ".destroy"
+		}
+
+		result = append(result, strings.Join(split, "/"))
+	}
+
+	return result
+}
+
+// GraphNodeEvalable
+func (n *NodeLocal) EvalTree() EvalNode {
+	return &EvalOpFilter{
+		Ops: []walkOperation{
+			walkInput,
+			walkValidate,
+			walkRefresh,
+			walkPlan,
+			walkApply,
+			walkDestroy,
+		},
+		Node: &EvalSequence{
+			Nodes: []EvalNode{
+			/*&EvalWriteLocal{
+				Name:  n.Config.Name,
+				Value: n.Config.RawConfig,
+			},*/
+			},
+		},
+	}
+}

terraform/test-fixtures/graph-builder-plan-basic/main.tf

@@ -22,3 +22,11 @@ resource "aws_instance" "web" {
 resource "aws_load_balancer" "weblb" {
     members = "${aws_instance.web.id_list}"
 }
+
+locals {
+  instance_id = "${aws_instance.web.id}"
+}
+
+output "instance_id" {
+  value = "${local.instance_id}"
+}

terraform/transform_local.go

@@ -0,0 +1,40 @@
+package terraform
+
+import (
+	"github.com/hashicorp/terraform/config/module"
+)
+
+// LocalTransformer is a GraphTransformer that adds all the local values
+// from the configuration to the graph.
+type LocalTransformer struct {
+	Module *module.Tree
+}
+
+func (t *LocalTransformer) Transform(g *Graph) error {
+	return t.transformModule(g, t.Module)
+}
+
+func (t *LocalTransformer) transformModule(g *Graph, m *module.Tree) error {
+	if m == nil {
+		// Can't have any locals if there's no config
+		return nil
+	}
+
+	for _, local := range m.Config().Locals {
+		node := &NodeLocal{
+			PathValue: normalizeModulePath(m.Path()),
+			Config:    local,
+		}
+
+		g.Add(node)
+	}
+
+	// Also populate locals for child modules
+	for _, c := range m.Children() {
+		if err := t.transformModule(g, c); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

terraform/transform_reference.go

@@ -296,6 +296,8 @@ func ReferenceFromInterpolatedVar(v config.InterpolatedVariable) []string {
 		return []string{fmt.Sprintf("%s.%d/%s.N", id, idx, id)}
 	case *config.UserVariable:
 		return []string{fmt.Sprintf("var.%s", v.Name)}
+	case *config.LocalVariable:
+		return []string{fmt.Sprintf("local.%s", v.Name)}
 	default:
 		return nil
 	}