Merge pull request #354 from hashicorp/f-dynamic-subgraph

Count can now interpolate values

config/config.go

@@ -4,6 +4,7 @@ package config
 
 import (
 	"fmt"
+	"strconv"
 	"strings"
 
 	"github.com/hashicorp/terraform/flatmap"
@@ -56,7 +57,7 @@ type ProviderConfig struct {
 type Resource struct {
 	Name         string
 	Type         string
-	Count        int
+	RawCount     *RawConfig
 	RawConfig    *RawConfig
 	Provisioners []*Provisioner
 	DependsOn    []string
@@ -120,6 +121,16 @@ func (r *Module) Id() string {
 	return fmt.Sprintf("%s", r.Name)
 }
 
+// Count returns the count of this resource.
+func (r *Resource) Count() (int, error) {
+	v, err := strconv.ParseInt(r.RawCount.Value().(string), 0, 0)
+	if err != nil {
+		return 0, err
+	}
+
+	return int(v), nil
+}
+
 // A unique identifier for this resource.
 func (r *Resource) Id() string {
 	return fmt.Sprintf("%s.%s", r.Type, r.Name)
@@ -244,11 +255,37 @@ func (c *Config) Validate() error {
 
 	// Validate resources
 	for n, r := range resources {
-		if r.Count < 1 {
+		// Verify count variables
+		for _, v := range r.RawCount.Variables {
+			switch v.(type) {
+			case *ModuleVariable:
 				errs = append(errs, fmt.Errorf(
-				"%s: count must be greater than or equal to 1",
+					"%s: resource count can't reference module variable: %s",
+					n,
+					v.FullKey()))
+			case *ResourceVariable:
+				errs = append(errs, fmt.Errorf(
+					"%s: resource count can't reference resource variable: %s",
+					n,
+					v.FullKey()))
+			case *UserVariable:
+				// Good
+			default:
+				panic("Unknown type in count var: " + n)
+			}
+		}
+
+		// Interpolate with a fixed number to verify that its a number
+		r.RawCount.interpolate(func(Interpolation) (string, error) {
+			return "5", nil
+		})
+		_, err := strconv.ParseInt(r.RawCount.Value().(string), 0, 0)
+		if err != nil {
+			errs = append(errs, fmt.Errorf(
+				"%s: resource count must be an integer",
 				n))
 		}
+		r.RawCount.init()
 
 		for _, d := range r.DependsOn {
 			if _, ok := resources[d]; !ok {
@@ -267,8 +304,7 @@ func (c *Config) Validate() error {
 			}
 
 			id := fmt.Sprintf("%s.%s", rv.Type, rv.Name)
-			r, ok := resources[id]
-			if !ok {
+			if _, ok := resources[id]; !ok {
 				errs = append(errs, fmt.Errorf(
 					"%s: unknown resource '%s' referenced in variable %s",
 					source,
@@ -276,18 +312,6 @@ func (c *Config) Validate() error {
 					rv.FullKey()))
 				continue
 			}
-
-			// If it is a multi reference and resource has a single
-			// count, it is an error.
-			if r.Count > 1 && !rv.Multi {
-				errs = append(errs, fmt.Errorf(
-					"%s: variable '%s' must specify index for multi-count "+
-						"resource %s",
-					source,
-					rv.FullKey(),
-					id))
-				continue
-			}
 		}
 	}
 
@@ -327,6 +351,9 @@ func (c *Config) InterpolatedVariables() map[string][]InterpolatedVariable {
 
 	for _, rc := range c.Resources {
 		source := fmt.Sprintf("resource '%s'", rc.Id())
+		for _, v := range rc.RawCount.Variables {
+			result[source] = append(result[source], v)
+		}
 		for _, v := range rc.RawConfig.Variables {
 			result[source] = append(result[source], v)
 		}
@@ -400,8 +427,8 @@ func (r *Resource) mergerMerge(m merger) merger {
 	result.Type = r2.Type
 	result.RawConfig = result.RawConfig.merge(r2.RawConfig)
 
-	if r2.Count > 0 {
-		result.Count = r2.Count
+	if r2.RawCount.Value() != "1" {
+		result.RawCount = r2.RawCount
 	}
 
 	if len(r2.Provisioners) > 0 {

config/config_string.go

@@ -190,10 +190,10 @@ func resourcesStr(rs []*Resource) string {
 	for _, i := range order {
 		r := rs[i]
 		result += fmt.Sprintf(
-			"%s[%s] (x%d)\n",
+			"%s[%s] (x%s)\n",
 			r.Type,
 			r.Name,
-			r.Count)
+			r.RawCount.Value())
 
 		ks := make([]string, 0, len(r.RawConfig.Raw))
 		for k, _ := range r.RawConfig.Raw {

config/config_test.go

@@ -9,6 +9,36 @@ import (
 // This is the directory where our test fixtures are.
 const fixtureDir = "./test-fixtures"
 
+func TestConfigCount(t *testing.T) {
+	c := testConfig(t, "count-int")
+	actual, err := c.Resources[0].Count()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if actual != 5 {
+		t.Fatalf("bad: %#v", actual)
+	}
+}
+
+func TestConfigCount_string(t *testing.T) {
+	c := testConfig(t, "count-string")
+	actual, err := c.Resources[0].Count()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if actual != 5 {
+		t.Fatalf("bad: %#v", actual)
+	}
+}
+
+func TestConfigCount_var(t *testing.T) {
+	c := testConfig(t, "count-var")
+	_, err := c.Resources[0].Count()
+	if err == nil {
+		t.Fatalf("should error")
+	}
+}
+
 func TestConfigValidate(t *testing.T) {
 	c := testConfig(t, "validate-good")
 	if err := c.Validate(); err != nil {
@@ -23,27 +53,41 @@ func TestConfigValidate_badDependsOn(t *testing.T) {
 	}
 }
 
-func TestConfigValidate_badMultiResource(t *testing.T) {
-	c := testConfig(t, "validate-bad-multi-resource")
+func TestConfigValidate_countInt(t *testing.T) {
+	c := testConfig(t, "validate-count-int")
+	if err := c.Validate(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}
+
+func TestConfigValidate_countModuleVar(t *testing.T) {
+	c := testConfig(t, "validate-count-module-var")
 	if err := c.Validate(); err == nil {
 		t.Fatal("should not be valid")
 	}
 }
 
-func TestConfigValidate_countBelowZero(t *testing.T) {
-	c := testConfig(t, "validate-count-below-zero")
+func TestConfigValidate_countNotInt(t *testing.T) {
+	c := testConfig(t, "validate-count-not-int")
 	if err := c.Validate(); err == nil {
 		t.Fatal("should not be valid")
 	}
 }
 
-func TestConfigValidate_countZero(t *testing.T) {
-	c := testConfig(t, "validate-count-zero")
+func TestConfigValidate_countResourceVar(t *testing.T) {
+	c := testConfig(t, "validate-count-resource-var")
 	if err := c.Validate(); err == nil {
 		t.Fatal("should not be valid")
 	}
 }
 
+func TestConfigValidate_countUserVar(t *testing.T) {
+	c := testConfig(t, "validate-count-user-var")
+	if err := c.Validate(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}
+
 func TestConfigValidate_dupModule(t *testing.T) {
 	c := testConfig(t, "validate-dup-module")
 	if err := c.Validate(); err == nil {
@@ -100,6 +144,13 @@ func TestConfigValidate_unknownVar(t *testing.T) {
 	}
 }
 
+func TestConfigValidate_unknownVarCount(t *testing.T) {
+	c := testConfig(t, "validate-unknownvar-count")
+	if err := c.Validate(); err == nil {
+		t.Fatal("should not be valid")
+	}
+}
+
 func TestConfigValidate_varDefault(t *testing.T) {
 	c := testConfig(t, "validate-var-default")
 	if err := c.Validate(); err != nil {

config/loader_hcl.go

@@ -406,7 +406,7 @@ func loadResourcesHcl(os *hclobj.Object) ([]*Resource, error) {
 			}
 
 			// If we have a count, then figure it out
-			var count int = 1
+			var count string = "1"
 			if o := obj.Get("count", false); o != nil {
 				err = hcl.DecodeObject(&count, o)
 				if err != nil {
@@ -417,6 +417,13 @@ func loadResourcesHcl(os *hclobj.Object) ([]*Resource, error) {
 						err)
 				}
 			}
+			countConfig, err := NewRawConfig(map[string]interface{}{
+				"count": count,
+			})
+			if err != nil {
+				return nil, err
+			}
+			countConfig.Key = "count"
 
 			// If we have depends fields, then add those in
 			var dependsOn []string
@@ -475,7 +482,7 @@ func loadResourcesHcl(os *hclobj.Object) ([]*Resource, error) {
 			result = append(result, &Resource{
 				Name:         k,
 				Type:         t.Key,
-				Count:        count,
+				RawCount:     countConfig,
 				RawConfig:    rawConfig,
 				Provisioners: provisioners,
 				DependsOn:    dependsOn,

config/raw_config.go

@@ -24,6 +24,7 @@ const UnknownVariableValue = "74D93920-ED26-11E3-AC10-0800200C9A66"
 // RawConfig supports a query-like interface to request
 // information from deep within the structure.
 type RawConfig struct {
+	Key            string
 	Raw            map[string]interface{}
 	Interpolations []Interpolation
 	Variables      map[string]InterpolatedVariable
@@ -43,6 +44,18 @@ func NewRawConfig(raw map[string]interface{}) (*RawConfig, error) {
 	return result, nil
 }
 
+// Value returns the value of the configuration if this configuration
+// has a Key set. If this does not have a Key set, nil will be returned.
+func (r *RawConfig) Value() interface{} {
+	if c := r.Config(); c != nil {
+		if v, ok := c[r.Key]; ok {
+			return v
+		}
+	}
+
+	return r.Raw[r.Key]
+}
+
 // Config returns the entire configuration with the variables
 // interpolated from any call to Interpolate.
 //
@@ -66,24 +79,9 @@ func (r *RawConfig) Config() map[string]interface{} {
 //
 // If a variable key is missing, this will panic.
 func (r *RawConfig) Interpolate(vs map[string]string) error {
-	config, err := copystructure.Copy(r.Raw)
-	if err != nil {
-		return err
-	}
-	r.config = config.(map[string]interface{})
-
-	fn := func(i Interpolation) (string, error) {
+	return r.interpolate(func(i Interpolation) (string, error) {
 		return i.Interpolate(vs)
-	}
-
-	w := &interpolationWalker{F: fn, Replace: true}
-	err = reflectwalk.Walk(r.config, w)
-	if err != nil {
-		return err
-	}
-
-	r.unknownKeys = w.unknownKeys
-	return nil
+	})
 }
 
 func (r *RawConfig) init() error {
@@ -113,6 +111,23 @@ func (r *RawConfig) init() error {
 	return nil
 }
 
+func (r *RawConfig) interpolate(fn interpolationWalkerFunc) error {
+	config, err := copystructure.Copy(r.Raw)
+	if err != nil {
+		return err
+	}
+	r.config = config.(map[string]interface{})
+
+	w := &interpolationWalker{F: fn, Replace: true}
+	err = reflectwalk.Walk(r.config, w)
+	if err != nil {
+		return err
+	}
+
+	r.unknownKeys = w.unknownKeys
+	return nil
+}
+
 func (r *RawConfig) merge(r2 *RawConfig) *RawConfig {
 	rawRaw, err := copystructure.Copy(r.Raw)
 	if err != nil {
@@ -140,11 +155,15 @@ func (r *RawConfig) UnknownKeys() []string {
 
 // See GobEncode
 func (r *RawConfig) GobDecode(b []byte) error {
-	err := gob.NewDecoder(bytes.NewReader(b)).Decode(&r.Raw)
+	var data gobRawConfig
+	err := gob.NewDecoder(bytes.NewReader(b)).Decode(&data)
 	if err != nil {
 		return err
 	}
 
+	r.Key = data.Key
+	r.Raw = data.Raw
+
 	return r.init()
 }
 
@@ -153,10 +172,20 @@ func (r *RawConfig) GobDecode(b []byte) error {
 // tree of interpolated variables is recomputed on decode, since it is
 // referentially transparent.
 func (r *RawConfig) GobEncode() ([]byte, error) {
+	data := gobRawConfig{
+		Key: r.Key,
+		Raw: r.Raw,
+	}
+
 	var buf bytes.Buffer
-	if err := gob.NewEncoder(&buf).Encode(r.Raw); err != nil {
+	if err := gob.NewEncoder(&buf).Encode(data); err != nil {
 		return nil, err
 	}
 
 	return buf.Bytes(), nil
 }
+
+type gobRawConfig struct {
+	Key string
+	Raw map[string]interface{}
+}

config/raw_config_test.go

@@ -125,6 +125,36 @@ func TestRawConfig_unknown(t *testing.T) {
 	}
 }
 
+func TestRawConfigValue(t *testing.T) {
+	raw := map[string]interface{}{
+		"foo": "${var.bar}",
+	}
+
+	rc, err := NewRawConfig(raw)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	rc.Key = ""
+	if rc.Value() != nil {
+		t.Fatalf("bad: %#v", rc.Value())
+	}
+
+	rc.Key = "foo"
+	if rc.Value() != "${var.bar}" {
+		t.Fatalf("err: %#v", rc.Value())
+	}
+
+	vars := map[string]string{"var.bar": "baz"}
+	if err := rc.Interpolate(vars); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if rc.Value() != "baz" {
+		t.Fatalf("bad: %#v", rc.Value())
+	}
+}
+
 func TestRawConfig_implGob(t *testing.T) {
 	var _ gob.GobDecoder = new(RawConfig)
 	var _ gob.GobEncoder = new(RawConfig)

config/test-fixtures/count-int/main.tf

@@ -0,0 +1,3 @@
+resource "foo" "bar" {
+    count = 5
+}

config/test-fixtures/count-string/main.tf

@@ -0,0 +1,3 @@
+resource "foo" "bar" {
+    count = "5"
+}

config/test-fixtures/count-var/main.tf

@@ -0,0 +1,3 @@
+resource "foo" "bar" {
+    count = "${var.foo}"
+}

config/test-fixtures/validate-count-int/main.tf

@@ -0,0 +1,5 @@
+variable "foo" {}
+
+resource "aws_instance" "web" {
+    count = "${var.foo}"
+}

config/test-fixtures/validate-count-module-var/main.tf

@@ -0,0 +1,7 @@
+module "foo" {
+    source = "./bar"
+}
+
+resource "aws_instance" "web" {
+    count = "${module.foo.bar}"
+}

config/test-fixtures/validate-count-not-int/main.tf

@@ -0,0 +1,5 @@
+variable "foo" {}
+
+resource "aws_instance" "web" {
+    count = "nope${var.foo}"
+}

config/test-fixtures/validate-count-resource-var/main.tf

@@ -0,0 +1,5 @@
+resource "aws_instance" "foo" {}
+
+resource "aws_instance" "web" {
+    count = "${aws_instance.foo.bar}"
+}

config/test-fixtures/validate-count-user-var/main.tf

@@ -0,0 +1,5 @@
+variable "foo" {}
+
+resource "aws_instance" "web" {
+    count = "${var.foo}"
+}

config/test-fixtures/validate-unknownvar-count/main.tf

@@ -0,0 +1,5 @@
+resource "foo" "bar" {
+    default = "bar"
+    description = "bar"
+    count = "${var.bar}"
+}

terraform/context.go

@@ -869,7 +869,8 @@ func (c *walkContext) planDestroyWalkFn() depgraph.WalkFunc {
 	result := c.Meta.(*Plan)
 	result.init()
 
-	return func(n *depgraph.Noun) error {
+	var walkFn depgraph.WalkFunc
+	walkFn = func(n *depgraph.Noun) error {
 		switch m := n.Meta.(type) {
 		case *GraphNodeModule:
 			// Build another walkContext for this module and walk it.
@@ -883,7 +884,13 @@ func (c *walkContext) planDestroyWalkFn() depgraph.WalkFunc {
 
 			return wc.Walk()
 		case *GraphNodeResource:
+			// If we're expanding, then expand the nodes, and then rewalk the graph
+			if m.ExpandMode > ResourceExpandNone {
+				return c.genericWalkResource(m, walkFn)
+			}
+
 			r := m.Resource
+
 			if r.State != nil && r.State.ID != "" {
 				log.Printf("[DEBUG] %s: Making for destroy", r.Id)
 
@@ -901,6 +908,8 @@ func (c *walkContext) planDestroyWalkFn() depgraph.WalkFunc {
 
 		return nil
 	}
+
+	return walkFn
 }
 
 func (c *walkContext) refreshWalkFn() depgraph.WalkFunc {
@@ -947,7 +956,8 @@ func (c *walkContext) validateWalkFn() depgraph.WalkFunc {
 		meta.Children = make(map[string]*walkValidateMeta)
 	}
 
-	return func(n *depgraph.Noun) error {
+	var walkFn depgraph.WalkFunc
+	walkFn = func(n *depgraph.Noun) error {
 		// If it is the root node, ignore
 		if n.Name == GraphRootNode {
 			return nil
@@ -979,6 +989,28 @@ func (c *walkContext) validateWalkFn() depgraph.WalkFunc {
 				panic("resource should never be nil")
 			}
 
+			// If we're expanding, then expand the nodes, and then rewalk the graph
+			if rn.ExpandMode > ResourceExpandNone {
+				// Interpolate the count and verify it is non-negative
+				rc := NewResourceConfig(rn.Config.RawCount)
+				rc.interpolate(c)
+				count, err := rn.Config.Count()
+				if err == nil {
+					if count < 0 {
+						err = fmt.Errorf(
+							"%s error: count must be positive", rn.Resource.Id)
+					}
+				}
+				if err != nil {
+					l.Lock()
+					defer l.Unlock()
+					meta.Errs = append(meta.Errs, err)
+					return nil
+				}
+
+				return c.genericWalkResource(rn, walkFn)
+			}
+
 			// If it doesn't have a provider, that is a different problem
 			if rn.Resource.Provider == nil {
 				return nil
@@ -1051,13 +1083,16 @@ func (c *walkContext) validateWalkFn() depgraph.WalkFunc {
 
 		return nil
 	}
+
+	return walkFn
 }
 
 func (c *walkContext) genericWalkFn(cb genericWalkFunc) depgraph.WalkFunc {
 	// This will keep track of whether we're stopped or not
 	var stop uint32 = 0
 
-	return func(n *depgraph.Noun) error {
+	var walkFn depgraph.WalkFunc
+	walkFn = func(n *depgraph.Noun) error {
 		// If it is the root node, ignore
 		if n.Name == GraphRootNode {
 			return nil
@@ -1104,9 +1139,6 @@ func (c *walkContext) genericWalkFn(cb genericWalkFunc) depgraph.WalkFunc {
 			return wc.Walk()
 		case *GraphNodeResource:
 			// Continue, we care about this the most
-		case *GraphNodeResourceMeta:
-			// Skip it
-			return nil
 		case *GraphNodeResourceProvider:
 			sharedProvider := m.Provider
 
@@ -1135,6 +1167,11 @@ func (c *walkContext) genericWalkFn(cb genericWalkFunc) depgraph.WalkFunc {
 
 		rn := n.Meta.(*GraphNodeResource)
 
+		// If we're expanding, then expand the nodes, and then rewalk the graph
+		if rn.ExpandMode > ResourceExpandNone {
+			return c.genericWalkResource(rn, walkFn)
+		}
+
 		// Make sure that at least some resource configuration is set
 		if rn.Config == nil {
 			rn.Resource.Config = new(ResourceConfig)
@@ -1166,6 +1203,49 @@ func (c *walkContext) genericWalkFn(cb genericWalkFunc) depgraph.WalkFunc {
 
 		return nil
 	}
+
+	return walkFn
+}
+
+func (c *walkContext) genericWalkResource(
+	rn *GraphNodeResource, fn depgraph.WalkFunc) error {
+	// Interpolate the count
+	rc := NewResourceConfig(rn.Config.RawCount)
+	rc.interpolate(c)
+
+	// Expand the node to the actual resources
+	ns, err := rn.Expand()
+	if err != nil {
+		return err
+	}
+
+	// Go through all the nouns and run them in parallel, collecting
+	// any errors.
+	var l sync.Mutex
+	var wg sync.WaitGroup
+	errs := make([]error, 0, len(ns))
+	for _, n := range ns {
+		wg.Add(1)
+
+		go func(n *depgraph.Noun) {
+			defer wg.Done()
+			if err := fn(n); err != nil {
+				l.Lock()
+				defer l.Unlock()
+				errs = append(errs, err)
+			}
+		}(n)
+	}
+
+	// Wait for the subgraph
+	wg.Wait()
+
+	// If there are errors, then we should return them
+	if len(errs) > 0 {
+		return &multierror.Error{Errors: errs}
+	}
+
+	return nil
 }
 
 // applyProvisioners is used to run any provisioners a resource has
@@ -1417,12 +1497,17 @@ func (c *walkContext) computeResourceVariable(
 	module := c.Context.state.ModuleByPath(c.Path)
 
 	r, ok := module.Resources[id]
+	if !ok {
+		if v.Multi && v.Index == 0 {
+			r, ok = module.Resources[v.ResourceId()]
+		}
 		if !ok {
 			return "", fmt.Errorf(
 				"Resource '%s' not found for variable '%s'",
 				id,
 				v.FullKey())
 		}
+	}
 
 	if r.Primary == nil {
 		goto MISSING
@@ -1479,13 +1564,26 @@ func (c *walkContext) computeResourceMultiVariable(
 	// TODO: Not use only root module
 	module := c.Context.state.RootModule()
 
+	count, err := cr.Count()
+	if err != nil {
+		return "", fmt.Errorf(
+			"Error reading %s count: %s",
+			v.ResourceId(),
+			err)
+	}
+
+	// If we have no count, return empty
+	if count == 0 {
+		return "", nil
+	}
+
 	var values []string
-	for i := 0; i < cr.Count; i++ {
+	for i := 0; i < 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 {
+		if count == 1 {
 			id = v.ResourceId()
 		}
 

terraform/context_test.go

@@ -107,6 +107,25 @@ func TestContextValidate_badVar(t *testing.T) {
 	}
 }
 
+func TestContextValidate_countNegative(t *testing.T) {
+	p := testProvider("aws")
+	m := testModule(t, "validate-count-negative")
+	c := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	w, e := c.Validate()
+	if len(w) > 0 {
+		t.Fatalf("bad: %#v", w)
+	}
+	if len(e) == 0 {
+		t.Fatalf("bad: %#v", e)
+	}
+}
+
 func TestContextValidate_moduleBadResource(t *testing.T) {
 	m := testModule(t, "validate-module-bad-rc")
 	p := testProvider("aws")
@@ -2428,6 +2447,95 @@ func TestContextPlan_count(t *testing.T) {
 	}
 }
 
+func TestContextPlan_countComputed(t *testing.T) {
+	m := testModule(t, "plan-count-computed")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	_, err := ctx.Plan(nil)
+	if err == nil {
+		t.Fatal("should error")
+	}
+}
+
+func TestContextPlan_countVar(t *testing.T) {
+	m := testModule(t, "plan-count-var")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+		Variables: map[string]string{
+			"count": "3",
+		},
+	})
+
+	plan, err := ctx.Plan(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(plan.String())
+	expected := strings.TrimSpace(testTerraformPlanCountVarStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
+func TestContextPlan_countZero(t *testing.T) {
+	m := testModule(t, "plan-count-zero")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		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(testTerraformPlanCountZeroStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
+func TestContextPlan_countOneIndex(t *testing.T) {
+	m := testModule(t, "plan-count-one-index")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		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(testTerraformPlanCountOneIndexStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func TestContextPlan_countDecreaseToOne(t *testing.T) {
 	m := testModule(t, "plan-count-dec")
 	p := testProvider("aws")

terraform/diff.go

@@ -167,6 +167,19 @@ func (d *ModuleDiff) Empty() bool {
 	return true
 }
 
+// Instances returns the instance diffs for the id given. This can return
+// multiple instance diffs if there are counts within the resource.
+func (d *ModuleDiff) Instances(id string) []*InstanceDiff {
+	var result []*InstanceDiff
+	for k, diff := range d.Resources {
+		if strings.HasPrefix(k, id) && !diff.Empty() {
+			result = append(result, diff)
+		}
+	}
+
+	return result
+}
+
 // IsRoot says whether or not this module diff is for the root module.
 func (d *ModuleDiff) IsRoot() bool {
 	return reflect.DeepEqual(d.Path, rootModulePath)

terraform/graph.go

@@ -91,16 +91,12 @@ type GraphNodeResource struct {
 	Config               *config.Resource
 	Resource             *Resource
 	ResourceProviderNode 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 {
-	ID    string
-	Name  string
-	Type  string
-	Count int
+	// All the fields below are related to expansion. These are set by
+	// the graph but aren't useful individually.
+	ExpandMode ResourceExpandMode
+	Diff       *ModuleDiff
+	State      *ModuleState
 }
 
 // GraphNodeResourceProvider is a node type in the graph that represents
@@ -123,6 +119,16 @@ type graphSharedProvider struct {
 	parentNoun     *depgraph.Noun
 }
 
+// ResourceExpandMode specifies the expand behavior of the GraphNodeResource
+// node.
+type ResourceExpandMode byte
+
+const (
+	ResourceExpandNone ResourceExpandMode = iota
+	ResourceExpandApply
+	ResourceExpandDestroy
+)
+
 // Graph builds a dependency graph of all the resources for infrastructure
 // change.
 //
@@ -321,13 +327,6 @@ func graphEncodeDependencies(g *depgraph.Graph) {
 				}
 				inject = append(inject, target.Resource.Id)
 
-			case *GraphNodeResourceMeta:
-				// Inject each sub-resource as a depedency
-				for i := 0; i < target.Count; i++ {
-					id := fmt.Sprintf("%s.%d", target.ID, i)
-					inject = append(inject, id)
-				}
-
 			case *GraphNodeResourceProvider:
 				// Do nothing
 
@@ -372,8 +371,31 @@ func graphAddConfigResources(
 	meta := g.Meta.(*GraphMeta)
 
 	// This tracks all the resource nouns
-	nouns := make(map[string]*depgraph.Noun)
-	for _, r := range c.Resources {
+	nounsList := make([]*depgraph.Noun, len(c.Resources))
+	for i, r := range c.Resources {
+		name := r.Id()
+
+		// Build the noun
+		nounsList[i] = &depgraph.Noun{
+			Name: name,
+			Meta: &GraphNodeResource{
+				Index:  -1,
+				Config: r,
+				Resource: &Resource{
+					Id: name,
+					Info: &InstanceInfo{
+						Id:         name,
+						ModulePath: meta.ModulePath,
+						Type:       r.Type,
+					},
+				},
+				State:      mod.View(name),
+				ExpandMode: ResourceExpandApply,
+			},
+		}
+
+		/*
+			TODO: probably did something important, bring it back somehow
 			resourceNouns := make([]*depgraph.Noun, r.Count)
 			for i := 0; i < r.Count; i++ {
 				name := r.Id()
@@ -468,12 +490,7 @@ func graphAddConfigResources(
 			for _, n := range resourceNouns {
 				nouns[n.Name] = n
 			}
-	}
-
-	// Build the list of nouns that we iterate over
-	nounsList := make([]*depgraph.Noun, 0, len(nouns))
-	for _, n := range nouns {
-		nounsList = append(nounsList, n)
+		*/
 	}
 
 	g.Name = "terraform"
@@ -501,15 +518,33 @@ func graphAddDiff(g *depgraph.Graph, d *ModuleDiff) error {
 			continue
 		}
 
-		rd, ok := d.Resources[rn.Resource.Id]
-		if !ok {
+		change := false
+		destroy := false
+		diffs := d.Instances(rn.Resource.Id)
+		if len(diffs) == 0 {
 			continue
 		}
-		if rd.Empty() {
-			continue
+		for _, d := range diffs {
+			if d.Destroy {
+				destroy = true
 			}
 
-		if rd.Destroy {
+			if len(d.Attributes) > 0 {
+				change = true
+			}
+		}
+
+		// If we're expanding, save the diff so we can add it on later
+		if rn.ExpandMode > ResourceExpandNone {
+			rn.Diff = d
+		}
+
+		var rd *InstanceDiff
+		if rn.ExpandMode == ResourceExpandNone {
+			rd = diffs[0]
+		}
+
+		if destroy {
 			// If we're destroying, we create a new destroy node with
 			// the proper dependencies. Perform a dirty copy operation.
 			newNode := new(GraphNodeResource)
@@ -520,6 +555,11 @@ func graphAddDiff(g *depgraph.Graph, d *ModuleDiff) error {
 			// Make the diff _just_ the destroy.
 			newNode.Resource.Diff = &InstanceDiff{Destroy: true}
 
+			// Make sure ExpandDestroy is set if Expand
+			if newNode.ExpandMode == ResourceExpandApply {
+				newNode.ExpandMode = ResourceExpandDestroy
+			}
+
 			// Create the new node
 			newN := &depgraph.Noun{
 				Name: fmt.Sprintf("%s (destroy)", newNode.Resource.Id),
@@ -533,17 +573,19 @@ func graphAddDiff(g *depgraph.Graph, d *ModuleDiff) error {
 			// Append it to the list so we handle it later
 			nlist = append(nlist, newN)
 
+			if rd != nil {
 				// Mark the old diff to not destroy since we handle that in
 				// the dedicated node.
 				newDiff := new(InstanceDiff)
 				*newDiff = *rd
 				newDiff.Destroy = false
 				rd = newDiff
+			}
 
 			// The dependency ordering depends on if the CreateBeforeDestroy
 			// flag is enabled. If so, we must create the replacement first,
 			// and then destroy the old instance.
-			if rn.Config != nil && rn.Config.Lifecycle.CreateBeforeDestroy && !rd.Empty() {
+			if rn.Config != nil && rn.Config.Lifecycle.CreateBeforeDestroy && change {
 				dep := &depgraph.Dependency{
 					Name:   n.Name,
 					Source: newN,
@@ -560,11 +602,13 @@ func graphAddDiff(g *depgraph.Graph, d *ModuleDiff) error {
 
 				// Add a depedency from the root, since the create node
 				// does not depend on us
+				if g.Root != nil {
 					g.Root.Deps = append(g.Root.Deps, &depgraph.Dependency{
 						Name:   newN.Name,
 						Source: g.Root,
 						Target: newN,
 					})
+				}
 
 				// Set the ReplacePrimary flag on the new instance so that
 				// it will become the new primary, and Diposed flag on the
@@ -653,33 +697,6 @@ func graphAddDiff(g *depgraph.Graph, d *ModuleDiff) error {
 				num--
 				i--
 
-			case *GraphNodeResourceMeta:
-				// Check if any of the resources part of the meta node
-				// are being destroyed, because we must be destroyed first.
-				for i := 0; i < target.Count; i++ {
-					id := fmt.Sprintf("%s.%d", target.ID, i)
-					for _, n2 := range nlist {
-						rn2 := n2.Meta.(*GraphNodeResource)
-						if id == rn2.Resource.Id {
-							newDep := &depgraph.Dependency{
-								Name:   n.Name,
-								Source: n2,
-								Target: n,
-							}
-							injected[newDep] = struct{}{}
-							n2.Deps = append(n2.Deps, newDep)
-							break
-						}
-					}
-				}
-
-				// Drop the dependency, since there is
-				// nothing that needs to be done for a meta
-				// resource on destroy.
-				deps[i], deps[num-1] = deps[num-1], nil
-				num--
-				i--
-
 			case *GraphNodeModule:
 				// We invert any module dependencies so we're destroyed
 				// first, before any modules are applied.
@@ -877,7 +894,7 @@ func graphAddOrphanDeps(g *depgraph.Graph, mod *ModuleState) {
 			}
 
 			for _, depName := range rs.Dependencies {
-				if compareName != depName {
+				if !strings.HasPrefix(depName, compareName) {
 					continue
 				}
 				dep := &depgraph.Dependency{
@@ -886,6 +903,7 @@ func graphAddOrphanDeps(g *depgraph.Graph, mod *ModuleState) {
 					Target: n2,
 				}
 				n.Deps = append(n.Deps, dep)
+				break
 			}
 		}
 	}
@@ -999,8 +1017,6 @@ func graphAddRoot(g *depgraph.Graph) {
 			if m.Index != -1 {
 				continue
 			}
-		case *GraphNodeResourceMeta:
-			// Always in the graph
 		case *GraphNodeResourceProvider:
 			// ResourceProviders don't need to be in the root deps because
 			// they're always pointed to by some resource.
@@ -1030,8 +1046,12 @@ func graphAddVariableDeps(g *depgraph.Graph) {
 
 		case *GraphNodeResource:
 			if m.Config != nil {
+				// Handle the count variables
+				vars := m.Config.RawCount.Variables
+				nounAddVariableDeps(g, n, vars, false)
+
 				// Handle the resource variables
-				vars := m.Config.RawConfig.Variables
+				vars = m.Config.RawConfig.Variables
 				nounAddVariableDeps(g, n, vars, false)
 			}
 
@@ -1573,6 +1593,211 @@ func (p *graphSharedProvider) MergeConfig(
 	return NewResourceConfig(rc)
 }
 
+// Expand will expand this node into a subgraph if Expand is set.
+func (n *GraphNodeResource) Expand() ([]*depgraph.Noun, error) {
+	// Expand the count out, which should be interpolated at this point.
+	count, err := n.Config.Count()
+	if err != nil {
+		return nil, err
+	}
+	log.Printf("[DEBUG] %s: expanding to count = %d", n.Resource.Id, count)
+
+	// TODO: can we DRY this up?
+	g := new(depgraph.Graph)
+	g.Meta = &GraphMeta{
+		ModulePath: n.Resource.Info.ModulePath,
+	}
+
+	// Determine the nodes to create. If we're just looking for the
+	// nodes to create, return that.
+	n.expand(g, count)
+
+	// Add in the diff if we have it
+	if n.Diff != nil {
+		if err := graphAddDiff(g, n.Diff); err != nil {
+			return nil, err
+		}
+	}
+
+	// If we're just expanding the apply, then filter those out and
+	// return them now.
+	if n.ExpandMode == ResourceExpandApply {
+		return n.finalizeNouns(g, false), nil
+	}
+
+	if n.State != nil {
+		// TODO: orphans
+
+		// Add the tainted resources
+		graphAddTainted(g, n.State)
+	}
+
+	return n.finalizeNouns(g, true), nil
+}
+
+// expand expands this resource and adds the resources to the graph. It
+// adds both create and destroy resources.
+func (n *GraphNodeResource) expand(g *depgraph.Graph, count int) {
+	// Create the list of nouns
+	result := make([]*depgraph.Noun, 0, count)
+
+	// Build the key set so we know what is removed
+	var keys map[string]struct{}
+	if n.State != nil {
+		keys = make(map[string]struct{})
+		for k, _ := range n.State.Resources {
+			keys[k] = struct{}{}
+		}
+	}
+
+	// First thing, expand the counts that we have defined for our
+	// current config into the full set of resources that are being
+	// created.
+	r := n.Config
+	for i := 0; i < count; i++ {
+		name := r.Id()
+		index := -1
+
+		// 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 count > 1 {
+			name = fmt.Sprintf("%s.%d", name, i)
+			index = i
+		}
+
+		var state *ResourceState
+		if n.State != nil {
+			// Lookup the resource state
+			if s, ok := n.State.Resources[name]; ok {
+				state = s
+				delete(keys, name)
+			}
+
+			if state == nil {
+				if count == 1 {
+					// If the count is one, check the state for ".0"
+					// appended, which might exist if we go from
+					// count > 1 to count == 1.
+					k := r.Id() + ".0"
+					state = n.State.Resources[k]
+					delete(keys, k)
+				} else if i == 0 {
+					// If count is greater than one, check for state
+					// with just the ID, which might exist if we go
+					// from count == 1 to count > 1
+					state = n.State.Resources[r.Id()]
+					delete(keys, r.Id())
+				}
+			}
+		}
+
+		if state == nil {
+			state = &ResourceState{
+				Type: r.Type,
+			}
+		}
+
+		flags := FlagPrimary
+		if len(state.Tainted) > 0 {
+			flags |= FlagHasTainted
+		}
+
+		// Copy the base resource so we can fill it in
+		resource := n.copyResource(name)
+		resource.State = state.Primary
+		resource.Flags = flags
+
+		// Add the result
+		result = append(result, &depgraph.Noun{
+			Name: name,
+			Meta: &GraphNodeResource{
+				Index:    index,
+				Config:   r,
+				Resource: resource,
+			},
+		})
+	}
+
+	// Go over the leftover keys which are orphans (decreasing counts)
+	for k, _ := range keys {
+		rs := n.State.Resources[k]
+
+		resource := n.copyResource(k)
+		resource.Config = NewResourceConfig(nil)
+		resource.State = rs.Primary
+		resource.Flags = FlagOrphan
+
+		noun := &depgraph.Noun{
+			Name: k,
+			Meta: &GraphNodeResource{
+				Index:    -1,
+				Resource: resource,
+			},
+		}
+
+		result = append(result, noun)
+	}
+
+	g.Nouns = append(g.Nouns, result...)
+}
+
+// copyResource copies the Resource structure to assign to a subgraph.
+func (n *GraphNodeResource) copyResource(id string) *Resource {
+	info := *n.Resource.Info
+	info.Id = id
+	resource := *n.Resource
+	resource.Id = id
+	resource.Info = &info
+	resource.Config = NewResourceConfig(n.Config.RawConfig)
+	return &resource
+}
+
+func (n *GraphNodeResource) finalizeNouns(
+	g *depgraph.Graph, destroy bool) []*depgraph.Noun {
+	result := make([]*depgraph.Noun, 0, len(g.Nouns))
+	for _, n := range g.Nouns {
+		rn, ok := n.Meta.(*GraphNodeResource)
+		if !ok {
+			continue
+		}
+
+		// If the diff is nil, then we're not destroying, so append only
+		// in that case.
+		if rn.Resource.Diff == nil {
+			if !destroy {
+				result = append(result, n)
+			}
+
+			continue
+		}
+
+		// If we are destroying, append it only if we care about destroys
+		if rn.Resource.Diff.Destroy {
+			if destroy {
+				result = append(result, n)
+			}
+
+			continue
+		}
+
+		// If this is an oprhan, we only care about it if we're destroying.
+		if rn.Resource.Flags&FlagOrphan != 0 {
+			if destroy {
+				result = append(result, n)
+			}
+
+			continue
+		}
+
+		// If we're not destroying, then add it only if we don't
+		// care about deploys.
+		if !destroy {
+			result = append(result, n)
+		}
+	}
+	return result
+}
+
 // matchingPrefixes takes a resource type and a set of resource
 // providers we know about by prefix and returns a list of prefixes
 // that might be valid for that resource.

terraform/graph_dot.go

@@ -7,7 +7,6 @@ import (
 	"strings"
 
 	"github.com/hashicorp/terraform/depgraph"
-	"github.com/hashicorp/terraform/digraph"
 )
 
 // GraphDotOpts are options for turning a graph into dot format.
@@ -221,6 +220,7 @@ func graphDotAddResources(
 	}
 
 	// Handle the meta resources
+	/*
 	edgeBuf.Reset()
 	for _, n := range g.Nouns {
 		_, ok := n.Meta.(*GraphNodeResourceMeta)
@@ -264,6 +264,7 @@ func graphDotAddResources(
 		buf.WriteString(edgeBuf.String())
 		buf.WriteString("\n")
 	}
+	*/
 }
 
 func graphDotAddResourceProviders(

terraform/graph_test.go

@@ -7,7 +7,7 @@ import (
 	"testing"
 )
 
-func TestGraph(t *testing.T) {
+func TestGraph_basic(t *testing.T) {
 	m := testModule(t, "graph-basic")
 
 	g, err := Graph(&GraphOpts{Module: m})
@@ -43,6 +43,21 @@ func TestGraph_count(t *testing.T) {
 	}
 }
 
+func TestGraph_varResource(t *testing.T) {
+	m := testModule(t, "graph-count-var-resource")
+
+	g, err := Graph(&GraphOpts{Module: m})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphCountVarResourceStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 func TestGraph_cycle(t *testing.T) {
 	m := testModule(t, "graph-cycle")
 
@@ -447,6 +462,8 @@ func TestGraphAddDiff(t *testing.T) {
 		t.Fatalf("bad:\n\n%s", actual)
 	}
 
+	/*
+	TODO: test this somewhere
 	// Verify that the state has been added
 	n := g.Noun("aws_instance.foo")
 	rn := n.Meta.(*GraphNodeResource)
@@ -456,6 +473,7 @@ func TestGraphAddDiff(t *testing.T) {
 	if !reflect.DeepEqual(actual2, expected2) {
 		t.Fatalf("bad: %#v", actual2)
 	}
+	*/
 }
 
 func TestGraphAddDiff_destroy(t *testing.T) {
@@ -609,13 +627,11 @@ func TestGraphAddDiff_destroy_counts(t *testing.T) {
 	}
 
 	// Verify that the state has been added
-	n := g.Noun("aws_instance.web.0 (destroy)")
+	n := g.Noun("aws_instance.web (destroy)")
 	rn := n.Meta.(*GraphNodeResource)
 
-	expected2 := &InstanceDiff{Destroy: true}
-	actual2 := rn.Resource.Diff
-	if !reflect.DeepEqual(actual2, expected2) {
-		t.Fatalf("bad: %#v", actual2)
+	if rn.ExpandMode != ResourceExpandDestroy {
+		t.Fatalf("bad: %#v", rn)
 	}
 
 	// Verify that our original structure has not been modified
@@ -816,13 +832,13 @@ func TestGraphEncodeDependencies_count(t *testing.T) {
 	// This should encode the dependency information into the state
 	graphEncodeDependencies(g)
 
-	web := g.Noun("aws_instance.web.0").Meta.(*GraphNodeResource).Resource
+	web := g.Noun("aws_instance.web").Meta.(*GraphNodeResource).Resource
 	if len(web.Dependencies) != 0 {
 		t.Fatalf("bad: %#v", web)
 	}
 
 	weblb := g.Noun("aws_load_balancer.weblb").Meta.(*GraphNodeResource).Resource
-	if len(weblb.Dependencies) != 3 {
+	if len(weblb.Dependencies) != 1 {
 		t.Fatalf("bad: %#v", weblb)
 	}
 }
@@ -956,12 +972,6 @@ root
 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
@@ -969,6 +979,19 @@ root
   root -> aws_load_balancer.weblb
 `
 
+const testTerraformGraphCountVarResourceStr = `
+root: root
+aws_instance.foo
+aws_instance.web
+  aws_instance.web -> aws_instance.foo
+aws_load_balancer.weblb
+  aws_load_balancer.weblb -> aws_instance.web
+root
+  root -> aws_instance.foo
+  root -> aws_instance.web
+  root -> aws_load_balancer.weblb
+`
+
 const testTerraformGraphDependsStr = `
 root: root
 aws_instance.db
@@ -982,12 +1005,7 @@ root
 const testTerraformGraphDependsCountStr = `
 root: root
 aws_instance.db
-  aws_instance.db -> aws_instance.db.0
-  aws_instance.db -> aws_instance.db.1
-aws_instance.db.0
-  aws_instance.db.0 -> aws_instance.web
-aws_instance.db.1
-  aws_instance.db.1 -> aws_instance.web
+  aws_instance.db -> aws_instance.web
 aws_instance.web
 root
   root -> aws_instance.db
@@ -1024,21 +1042,9 @@ root
 const testTerraformGraphDiffDestroyCountsStr = `
 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.0 -> aws_instance.web.0 (destroy)
-aws_instance.web.0 (destroy)
-  aws_instance.web.0 (destroy) -> aws_load_balancer.weblb (destroy)
-aws_instance.web.1
-  aws_instance.web.1 -> aws_instance.web.1 (destroy)
-aws_instance.web.1 (destroy)
-  aws_instance.web.1 (destroy) -> aws_load_balancer.weblb (destroy)
-aws_instance.web.2
-  aws_instance.web.2 -> aws_instance.web.2 (destroy)
-aws_instance.web.2 (destroy)
-  aws_instance.web.2 (destroy) -> aws_load_balancer.weblb (destroy)
+  aws_instance.web -> aws_instance.web (destroy)
+aws_instance.web (destroy)
+  aws_instance.web (destroy) -> aws_load_balancer.weblb (destroy)
 aws_load_balancer.weblb
   aws_load_balancer.weblb -> aws_instance.web
   aws_load_balancer.weblb -> aws_load_balancer.weblb (destroy)
@@ -1197,16 +1203,8 @@ root
 const testTerraformGraphCountOrphanStr = `
 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.old
-  aws_load_balancer.old -> aws_instance.web.0
-  aws_load_balancer.old -> aws_instance.web.1
-  aws_load_balancer.old -> aws_instance.web.2
+  aws_load_balancer.old -> aws_instance.web
 aws_load_balancer.weblb
   aws_load_balancer.weblb -> aws_instance.web
 root

terraform/state.go

@@ -198,9 +198,10 @@ func (m *ModuleState) Orphans(c *config.Config) []string {
 	for _, r := range c.Resources {
 		delete(keys, r.Id())
 
-		// Mark all the counts as not orphans.
-		for i := 0; i < r.Count; i++ {
-			delete(keys, fmt.Sprintf("%s.%d", r.Id(), i))
+		for k, _ := range keys {
+			if strings.HasPrefix(k, r.Id()+".") {
+				delete(keys, k)
+			}
 		}
 	}
 
@@ -212,6 +213,24 @@ func (m *ModuleState) Orphans(c *config.Config) []string {
 	return result
 }
 
+// View returns a view with the given resource prefix.
+func (m *ModuleState) View(id string) *ModuleState {
+	if m == nil {
+		return m
+	}
+
+	r := m.deepcopy()
+	for k, _ := range r.Resources {
+		if id == k || strings.HasPrefix(k, id+".") {
+			continue
+		}
+
+		delete(r.Resources, k)
+	}
+
+	return r
+}
+
 func (m *ModuleState) init() {
 	if m.Outputs == nil {
 		m.Outputs = make(map[string]string)

terraform/state_v1.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"sort"
+	"strings"
 	"sync"
 
 	"github.com/hashicorp/terraform/config"
@@ -80,9 +81,10 @@ func (s *StateV1) Orphans(c *config.Config) []string {
 	for _, r := range c.Resources {
 		delete(keys, r.Id())
 
-		// Mark all the counts as not orphans.
-		for i := 0; i < r.Count; i++ {
-			delete(keys, fmt.Sprintf("%s.%d", r.Id(), i))
+		for k, _ := range keys {
+			if strings.HasPrefix(k, r.Id()+".") {
+				delete(keys, k)
+			}
 		}
 	}
 

terraform/terraform_test.go

@@ -477,6 +477,54 @@ STATE:
 <no state>
 `
 
+const testTerraformPlanCountOneIndexStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+
+const testTerraformPlanCountZeroStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => ""
+  type: "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+
+const testTerraformPlanCountVarStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => "foo,foo,foo"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo.0
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo.1
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo.2
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+
 const testTerraformPlanCountDecreaseStr = `
 DIFF:
 

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

@@ -0,0 +1,9 @@
+resource "aws_instance" "foo" {}
+
+resource "aws_instance" "web" {
+    count = "${aws_instance.foo.bar}"
+}
+
+resource "aws_load_balancer" "weblb" {
+    members = "${aws_instance.web.*.id}"
+}

terraform/test-fixtures/plan-count-computed/main.tf

@@ -0,0 +1,8 @@
+resource "aws_instance" "foo" {
+    num = "2"
+    compute = "foo"
+}
+
+resource "aws_instance" "bar" {
+    count = "${aws_instance.foo.foo}"
+}

terraform/test-fixtures/plan-count-one-index/main.tf

@@ -0,0 +1,8 @@
+resource "aws_instance" "foo" {
+    count = 1
+    foo = "foo"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.0.foo}"
+}

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

@@ -0,0 +1,10 @@
+variable "count" {}
+
+resource "aws_instance" "foo" {
+    count = "${var.count}"
+    foo = "foo"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.*.foo}"
+}

terraform/test-fixtures/plan-count-zero/main.tf

@@ -0,0 +1,8 @@
+resource "aws_instance" "foo" {
+    count = 0
+    foo = "foo"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.*.foo}"
+}

terraform/test-fixtures/validate-count-negative/main.tf

@@ -0,0 +1,3 @@
+resource "aws_instance" "test" {
+    count = "-5"
+}