terraform: turn multi-counts into multiple nodes

depgraph/graph.go

@@ -9,6 +9,7 @@ import (
 	"bytes"
 	"fmt"
 	"sort"
+	"strings"
 	"sync"
 
 	"github.com/hashicorp/terraform/digraph"
@@ -42,7 +43,34 @@ type ValidateError struct {
 }
 
 func (v *ValidateError) Error() string {
-	return "The depedency graph is not valid"
+	var msgs []string
+
+	if v.MissingRoot {
+		msgs = append(msgs, "The graph has no single root")
+	}
+
+	for _, n := range v.Unreachable {
+		msgs = append(msgs, fmt.Sprintf(
+			"Unreachable node: %s", n.Name))
+	}
+
+	for _, c := range v.Cycles {
+		cycleNodes := make([]string, len(c))
+		for i, n := range c {
+			cycleNodes[i] = n.Name
+		}
+
+		msgs = append(msgs, fmt.Sprintf(
+			"Cycle: %s", strings.Join(cycleNodes, " -> ")))
+	}
+
+	for i, m := range msgs {
+		msgs[i] = fmt.Sprintf("* %s", m)
+	}
+
+	return fmt.Sprintf(
+		"The dependency graph is not valid:\n\n%s",
+		strings.Join(msgs, "\n"))
 }
 
 // ConstraintError is used to return detailed violation

terraform/graph.go

@@ -45,8 +45,12 @@ type GraphOpts struct {
 // graph. This node is just a placemarker and has no associated functionality.
 const GraphRootNode = "root"
 
-// GraphNodeResource is a node type in the graph that represents a resource.
+// GraphNodeResource is a node type in the graph that represents a resource
+// that will be created or managed. Unlike the GraphNodeResourceMeta node,
+// this represents a _single_, _resource_ to be managed, not a set of resources
+// or a component of a resource.
 type GraphNodeResource struct {
+	Index              int
 	Type               string
 	Config             *config.Resource
 	Orphan             bool
@@ -54,6 +58,15 @@ type GraphNodeResource struct {
 	ResourceProviderID string
 }
 
+// GraphNodeResourceMeta is a node type in the graph that represents the
+// metadata for a resource. There will be one meta node for every resource
+// in the configuration.
+type GraphNodeResourceMeta struct {
+	Name  string
+	Type  string
+	Count int
+}
+
 // GraphNodeResourceProvider is a node type in the graph that represents
 // the configuration for a resource provider.
 type GraphNodeResourceProvider struct {
@@ -152,18 +165,57 @@ func graphAddConfigResources(
 			}
 		}
 
-		noun := &depgraph.Noun{
-			Name: r.Id(),
+		resourceNouns := make([]*depgraph.Noun, r.Count)
+		for i := 0; i < r.Count; i++ {
+			name := r.Id()
+
+			// If we have a count that is more than one, then make sure
+			// we suffix with the number of the resource that this is.
+			if r.Count > 1 {
+				name = fmt.Sprintf("%s.%d", name, i)
+			}
+
+			resourceNouns[i] = &depgraph.Noun{
+				Name: name,
 				Meta: &GraphNodeResource{
 					Type:   r.Type,
 					Config: r,
 					Resource: &Resource{
-					Id:    r.Id(),
+						Id:    name,
 						State: state,
 					},
 				},
 			}
-		nouns[noun.Name] = noun
+		}
+
+		// If we have more than one, then create a meta node to track
+		// the resources.
+		if r.Count > 1 {
+			metaNoun := &depgraph.Noun{
+				Name: r.Id(),
+				Meta: &GraphNodeResourceMeta{
+					Name:  r.Id(),
+					Type:  r.Type,
+					Count: r.Count,
+				},
+			}
+
+			// Create the dependencies on this noun
+			for _, n := range resourceNouns {
+				metaNoun.Deps = append(metaNoun.Deps, &depgraph.Dependency{
+					Name:   n.Name,
+					Source: metaNoun,
+					Target: n,
+				})
+			}
+
+			// Assign it to the map so that we have it
+			nouns[metaNoun.Name] = metaNoun
+		}
+
+		for _, n := range resourceNouns {
+			nouns[n.Name] = n
+		}
 	}
 
 	// Build the list of nouns that we iterate over
@@ -357,7 +409,10 @@ func graphAddProviderConfigs(g *depgraph.Graph, c *config.Config) {
 	nounsList := make([]*depgraph.Noun, 0, 2)
 	pcNouns := make(map[string]*depgraph.Noun)
 	for _, noun := range g.Nouns {
-		resourceNode := noun.Meta.(*GraphNodeResource)
+		resourceNode, ok := noun.Meta.(*GraphNodeResource)
+		if !ok {
+			continue
+		}
 
 		// Look up the provider config for this resource
 		pcName := config.ProviderConfigName(resourceNode.Type, c.ProviderConfigs)
@@ -401,11 +456,6 @@ func graphAddProviderConfigs(g *depgraph.Graph, c *config.Config) {
 func graphAddRoot(g *depgraph.Graph) {
 	root := &depgraph.Noun{Name: GraphRootNode}
 	for _, n := range g.Nouns {
-		// The root only needs to depend on all the resources
-		if _, ok := n.Meta.(*GraphNodeResource); !ok {
-			continue
-		}
-
 		root.Deps = append(root.Deps, &depgraph.Dependency{
 			Name:   n.Name,
 			Source: root,

terraform/graph_test.go

@@ -27,6 +27,21 @@ func TestGraph_configRequired(t *testing.T) {
 	}
 }
 
+func TestGraph_count(t *testing.T) {
+	config := testConfig(t, "graph-count")
+
+	g, err := Graph(&GraphOpts{Config: config})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphCountStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 func TestGraph_cycle(t *testing.T) {
 	config := testConfig(t, "graph-cycle")
 
@@ -226,6 +241,25 @@ root
   root -> openstack_floating_ip.random
 `
 
+const testTerraformGraphCountStr = `
+root: root
+aws_instance.web
+  aws_instance.web -> aws_instance.web.0
+  aws_instance.web -> aws_instance.web.1
+  aws_instance.web -> aws_instance.web.2
+aws_instance.web.0
+aws_instance.web.1
+aws_instance.web.2
+aws_load_balancer.weblb
+  aws_load_balancer.weblb -> aws_instance.web
+root
+  root -> aws_instance.web
+  root -> aws_instance.web.0
+  root -> aws_instance.web.1
+  root -> aws_instance.web.2
+  root -> aws_load_balancer.weblb
+`
+
 const testTerraformGraphDiffStr = `
 root: root
 aws_instance.foo

terraform/test-fixtures/graph-count/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "web" {
+    count = 3
+}
+
+resource "aws_load_balancer" "weblb" {
+    members = "${aws_instance.web.*.id}"
+}