Merge pull request #1293 from hashicorp/f-targeted-ops

core: targeted operations

command/apply.go

@@ -93,6 +93,7 @@ func (c *ApplyCommand) Run(args []string) int {
 
 	// Build the context based on the arguments given
 	ctx, planned, err := c.Context(contextOpts{
+		Destroy:   c.Destroy,
 		Path:      configPath,
 		StatePath: c.Meta.statePath,
 	})
@@ -140,12 +141,7 @@ func (c *ApplyCommand) Run(args []string) int {
 			}
 		}
 
-		var opts terraform.PlanOpts
-		if c.Destroy {
-			opts.Destroy = true
-		}
-
-		if _, err := ctx.Plan(&opts); err != nil {
+		if _, err := ctx.Plan(); err != nil {
 			c.Ui.Error(fmt.Sprintf(
 				"Error creating plan: %s", err))
 			return 1
@@ -319,6 +315,10 @@ Options:
                          "-state". This can be used to preserve the old
                          state.
 
+  -target=resource       Resource to target. Operation will be limited to this
+                         resource and its dependencies. This flag can be used
+                         multiple times.
+
   -var 'foo=bar'         Set a variable in the Terraform configuration. This
                          flag can be set multiple times.
 
@@ -357,6 +357,10 @@ Options:
                          "-state". This can be used to preserve the old
                          state.
 
+  -target=resource       Resource to target. Operation will be limited to this
+                         resource and its dependencies. This flag can be used
+                         multiple times.
+
   -var 'foo=bar'         Set a variable in the Terraform configuration. This
                          flag can be set multiple times.
 

command/apply_destroy_test.go

@@ -116,6 +116,96 @@ func TestApply_destroyPlan(t *testing.T) {
 	}
 }
 
+func TestApply_destroyTargeted(t *testing.T) {
+	originalState := &terraform.State{
+		Modules: []*terraform.ModuleState{
+			&terraform.ModuleState{
+				Path: []string{"root"},
+				Resources: map[string]*terraform.ResourceState{
+					"test_instance.foo": &terraform.ResourceState{
+						Type: "test_instance",
+						Primary: &terraform.InstanceState{
+							ID: "i-ab123",
+						},
+					},
+					"test_load_balancer.foo": &terraform.ResourceState{
+						Type: "test_load_balancer",
+						Primary: &terraform.InstanceState{
+							ID: "lb-abc123",
+						},
+					},
+				},
+			},
+		},
+	}
+
+	statePath := testStateFile(t, originalState)
+
+	p := testProvider()
+	ui := new(cli.MockUi)
+	c := &ApplyCommand{
+		Destroy: true,
+		Meta: Meta{
+			ContextOpts: testCtxConfig(p),
+			Ui:          ui,
+		},
+	}
+
+	// Run the apply command pointing to our existing state
+	args := []string{
+		"-force",
+		"-target", "test_instance.foo",
+		"-state", statePath,
+		testFixturePath("apply-destroy-targeted"),
+	}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+
+	// Verify a new state exists
+	if _, err := os.Stat(statePath); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	f, err := os.Open(statePath)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer f.Close()
+
+	state, err := terraform.ReadState(f)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if state == nil {
+		t.Fatal("state should not be nil")
+	}
+
+	actualStr := strings.TrimSpace(state.String())
+	expectedStr := strings.TrimSpace(testApplyDestroyStr)
+	if actualStr != expectedStr {
+		t.Fatalf("bad:\n\n%s\n\n%s", actualStr, expectedStr)
+	}
+
+	// Should have a backup file
+	f, err = os.Open(statePath + DefaultBackupExtention)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	backupState, err := terraform.ReadState(f)
+	f.Close()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actualStr = strings.TrimSpace(backupState.String())
+	expectedStr = strings.TrimSpace(originalState.String())
+	if actualStr != expectedStr {
+		t.Fatalf("bad:\n\nactual:\n%s\n\nexpected:\nb%s", actualStr, expectedStr)
+	}
+}
+
 const testApplyDestroyStr = `
 <no state>
 `

command/flag_kv.go

@@ -85,3 +85,17 @@ func loadKVFile(rawPath string) (map[string]string, error) {
 
 	return result, nil
 }
+
+// FlagStringSlice is a flag.Value implementation for parsing targets from the
+// command line, e.g. -target=aws_instance.foo -target=aws_vpc.bar
+
+type FlagStringSlice []string
+
+func (v *FlagStringSlice) String() string {
+	return ""
+}
+func (v *FlagStringSlice) Set(raw string) error {
+	*v = append(*v, raw)
+
+	return nil
+}

command/meta.go

@@ -38,6 +38,9 @@ type Meta struct {
 	input         bool
 	variables     map[string]string
 
+	// Targets for this context (private)
+	targets []string
+
 	color bool
 	oldUi cli.Ui
 
@@ -126,6 +129,9 @@ func (m *Meta) Context(copts contextOpts) (*terraform.Context, bool, error) {
 		m.statePath = copts.StatePath
 	}
 
+	// Tell the context if we're in a destroy plan / apply
+	opts.Destroy = copts.Destroy
+
 	// Store the loaded state
 	state, err := m.State()
 	if err != nil {
@@ -267,6 +273,7 @@ func (m *Meta) contextOpts() *terraform.ContextOpts {
 		vs[k] = v
 	}
 	opts.Variables = vs
+	opts.Targets = m.targets
 	opts.UIInput = m.UIInput()
 
 	return &opts
@@ -278,6 +285,7 @@ func (m *Meta) flagSet(n string) *flag.FlagSet {
 	f.BoolVar(&m.input, "input", true, "input")
 	f.Var((*FlagKV)(&m.variables), "var", "variables")
 	f.Var((*FlagKVFile)(&m.variables), "var-file", "variable file")
+	f.Var((*FlagStringSlice)(&m.targets), "target", "resource to target")
 
 	if m.autoKey != "" {
 		f.Var((*FlagKVFile)(&m.autoVariables), m.autoKey, "variable file")
@@ -388,4 +396,7 @@ type contextOpts struct {
 
 	// GetMode is the module.GetMode to use when loading the module tree.
 	GetMode module.GetMode
+
+	// Set to true when running a destroy plan/apply.
+	Destroy bool
 }

command/plan.go

@@ -53,6 +53,7 @@ func (c *PlanCommand) Run(args []string) int {
 	}
 
 	ctx, _, err := c.Context(contextOpts{
+		Destroy:   destroy,
 		Path:      path,
 		StatePath: c.Meta.statePath,
 	})
@@ -86,7 +87,7 @@ func (c *PlanCommand) Run(args []string) int {
 		}
 	}
 
-	plan, err := ctx.Plan(&terraform.PlanOpts{Destroy: destroy})
+	plan, err := ctx.Plan()
 	if err != nil {
 		c.Ui.Error(fmt.Sprintf("Error running plan: %s", err))
 		return 1
@@ -168,6 +169,10 @@ Options:
                       up Terraform-managed resources. By default it will
                       use the state "terraform.tfstate" if it exists.
 
+  -target=resource    Resource to target. Operation will be limited to this
+                      resource and its dependencies. This flag can be used
+                      multiple times.
+
   -var 'foo=bar'      Set a variable in the Terraform configuration. This
                       flag can be set multiple times.
 

command/refresh.go

@@ -135,6 +135,10 @@ Options:
   -state-out=path     Path to write updated state file. By default, the
                       "-state" path will be used.
 
+  -target=resource    Resource to target. Operation will be limited to this
+                      resource and its dependencies. This flag can be used
+                      multiple times.
+
   -var 'foo=bar'      Set a variable in the Terraform configuration. This
                       flag can be set multiple times.
 

command/test-fixtures/apply-destroy-targeted/main.tf

@@ -0,0 +1,7 @@
+resource "test_instance" "foo" {
+  count = 3
+}
+
+resource "test_load_balancer" "foo" {
+  instances = ["${test_instance.foo.*.id}"]
+}

dag/dag.go

@@ -17,6 +17,40 @@ type AcyclicGraph struct {
 // WalkFunc is the callback used for walking the graph.
 type WalkFunc func(Vertex) error
 
+// Returns a Set that includes every Vertex yielded by walking down from the
+// provided starting Vertex v.
+func (g *AcyclicGraph) Ancestors(v Vertex) (*Set, error) {
+	s := new(Set)
+	start := asVertexList(g.DownEdges(v))
+	memoFunc := func(v Vertex) error {
+		s.Add(v)
+		return nil
+	}
+
+	if err := g.depthFirstWalk(start, memoFunc); err != nil {
+		return nil, err
+	}
+
+	return s, nil
+}
+
+// Returns a Set that includes every Vertex yielded by walking up from the
+// provided starting Vertex v.
+func (g *AcyclicGraph) Descendents(v Vertex) (*Set, error) {
+	s := new(Set)
+	start := asVertexList(g.UpEdges(v))
+	memoFunc := func(v Vertex) error {
+		s.Add(v)
+		return nil
+	}
+
+	if err := g.reverseDepthFirstWalk(start, memoFunc); err != nil {
+		return nil, err
+	}
+
+	return s, nil
+}
+
 // Root returns the root of the DAG, or an error.
 //
 // Complexity: O(V)
@@ -61,15 +95,11 @@ func (g *AcyclicGraph) TransitiveReduction() {
 
 	for _, u := range g.Vertices() {
 		uTargets := g.DownEdges(u)
-		vs := make([]Vertex, uTargets.Len())
-		for i, vRaw := range uTargets.List() {
-			vs[i] = vRaw.(Vertex)
-		}
+		vs := asVertexList(g.DownEdges(u))
 
 		g.depthFirstWalk(vs, func(v Vertex) error {
 			shared := uTargets.Intersection(g.DownEdges(v))
-			for _, raw := range shared.List() {
-				vPrime := raw.(Vertex)
+			for _, vPrime := range asVertexList(shared) {
 				g.RemoveEdge(BasicEdge(u, vPrime))
 			}
 
@@ -145,12 +175,10 @@ func (g *AcyclicGraph) Walk(cb WalkFunc) error {
 	for _, v := range vertices {
 		// Build our list of dependencies and the list of channels to
 		// wait on until we start executing for this vertex.
-		depsRaw := g.DownEdges(v).List()
-		deps := make([]Vertex, len(depsRaw))
+		deps := asVertexList(g.DownEdges(v))
 		depChs := make([]<-chan struct{}, len(deps))
-		for i, raw := range depsRaw {
-			deps[i] = raw.(Vertex)
-			depChs[i] = vertMap[deps[i]]
+		for i, dep := range deps {
+			depChs[i] = vertMap[dep]
 		}
 
 		// Get our channel so that we can close it when we're done
@@ -200,6 +228,16 @@ func (g *AcyclicGraph) Walk(cb WalkFunc) error {
 	return errs
 }
 
+// simple convenience helper for converting a dag.Set to a []Vertex
+func asVertexList(s *Set) []Vertex {
+	rawList := s.List()
+	vertexList := make([]Vertex, len(rawList))
+	for i, raw := range rawList {
+		vertexList[i] = raw.(Vertex)
+	}
+	return vertexList
+}
+
 // depthFirstWalk does a depth-first walk of the graph starting from
 // the vertices in start. This is not exported now but it would make sense
 // to export this publicly at some point.
@@ -233,3 +271,36 @@ func (g *AcyclicGraph) depthFirstWalk(start []Vertex, cb WalkFunc) error {
 
 	return nil
 }
+
+// reverseDepthFirstWalk does a depth-first walk _up_ the graph starting from
+// the vertices in start.
+func (g *AcyclicGraph) reverseDepthFirstWalk(start []Vertex, cb WalkFunc) error {
+	seen := make(map[Vertex]struct{})
+	frontier := make([]Vertex, len(start))
+	copy(frontier, start)
+	for len(frontier) > 0 {
+		// Pop the current vertex
+		n := len(frontier)
+		current := frontier[n-1]
+		frontier = frontier[:n-1]
+
+		// Check if we've seen this already and return...
+		if _, ok := seen[current]; ok {
+			continue
+		}
+		seen[current] = struct{}{}
+
+		// Visit the current node
+		if err := cb(current); err != nil {
+			return err
+		}
+
+		// Visit targets of this in reverse order.
+		targets := g.UpEdges(current).List()
+		for i := len(targets) - 1; i >= 0; i-- {
+			frontier = append(frontier, targets[i].(Vertex))
+		}
+	}
+
+	return nil
+}

dag/dag_test.go

@@ -126,6 +126,68 @@ func TestAcyclicGraphValidate_cycleSelf(t *testing.T) {
 	}
 }
 
+func TestAcyclicGraphAncestors(t *testing.T) {
+	var g AcyclicGraph
+	g.Add(1)
+	g.Add(2)
+	g.Add(3)
+	g.Add(4)
+	g.Add(5)
+	g.Connect(BasicEdge(0, 1))
+	g.Connect(BasicEdge(1, 2))
+	g.Connect(BasicEdge(2, 3))
+	g.Connect(BasicEdge(3, 4))
+	g.Connect(BasicEdge(4, 5))
+
+	actual, err := g.Ancestors(2)
+	if err != nil {
+		t.Fatalf("err: %#v", err)
+	}
+
+	expected := []Vertex{3, 4, 5}
+
+	if actual.Len() != len(expected) {
+		t.Fatalf("bad length! expected %#v to have len %d", actual, len(expected))
+	}
+
+	for _, e := range expected {
+		if !actual.Include(e) {
+			t.Fatalf("expected: %#v to include: %#v", expected, actual)
+		}
+	}
+}
+
+func TestAcyclicGraphDescendents(t *testing.T) {
+	var g AcyclicGraph
+	g.Add(1)
+	g.Add(2)
+	g.Add(3)
+	g.Add(4)
+	g.Add(5)
+	g.Connect(BasicEdge(0, 1))
+	g.Connect(BasicEdge(1, 2))
+	g.Connect(BasicEdge(2, 3))
+	g.Connect(BasicEdge(3, 4))
+	g.Connect(BasicEdge(4, 5))
+
+	actual, err := g.Descendents(2)
+	if err != nil {
+		t.Fatalf("err: %#v", err)
+	}
+
+	expected := []Vertex{0, 1}
+
+	if actual.Len() != len(expected) {
+		t.Fatalf("bad length! expected %#v to have len %d", actual, len(expected))
+	}
+
+	for _, e := range expected {
+		if !actual.Include(e) {
+			t.Fatalf("expected: %#v to include: %#v", expected, actual)
+		}
+	}
+}
+
 func TestAcyclicGraphWalk(t *testing.T) {
 	var g AcyclicGraph
 	g.Add(1)

helper/resource/testing.go

@@ -190,6 +190,7 @@ func testStep(
 	// Build the context
 	opts.Module = mod
 	opts.State = state
+	opts.Destroy = step.Destroy
 	ctx := terraform.NewContext(&opts)
 	if ws, es := ctx.Validate(); len(ws) > 0 || len(es) > 0 {
 		estrs := make([]string, len(es))
@@ -209,7 +210,7 @@ func testStep(
 	}
 
 	// Plan!
-	if p, err := ctx.Plan(&terraform.PlanOpts{Destroy: step.Destroy}); err != nil {
+	if p, err := ctx.Plan(); err != nil {
 		return state, fmt.Errorf(
 			"Error planning: %s", err)
 	} else {

terraform/context.go

@@ -33,6 +33,7 @@ const (
 // ContextOpts are the user-configurable options to create a context with
 // NewContext.
 type ContextOpts struct {
+	Destroy      bool
 	Diff         *Diff
 	Hooks        []Hook
 	Module       *module.Tree
@@ -40,6 +41,7 @@ type ContextOpts struct {
 	State        *State
 	Providers    map[string]ResourceProviderFactory
 	Provisioners map[string]ResourceProvisionerFactory
+	Targets      []string
 	Variables    map[string]string
 
 	UIInput UIInput
@@ -49,6 +51,7 @@ type ContextOpts struct {
 // perform operations on infrastructure. This structure is built using
 // NewContext. See the documentation for that.
 type Context struct {
+	destroy      bool
 	diff         *Diff
 	diffLock     sync.RWMutex
 	hooks        []Hook
@@ -58,6 +61,7 @@ type Context struct {
 	sh           *stopHook
 	state        *State
 	stateLock    sync.RWMutex
+	targets      []string
 	uiInput      UIInput
 	variables    map[string]string
 
@@ -95,12 +99,14 @@ func NewContext(opts *ContextOpts) *Context {
 	}
 
 	return &Context{
+		destroy:      opts.Destroy,
 		diff:         opts.Diff,
 		hooks:        hooks,
 		module:       opts.Module,
 		providers:    opts.Providers,
 		provisioners: opts.Provisioners,
 		state:        state,
+		targets:      opts.Targets,
 		uiInput:      opts.UIInput,
 		variables:    opts.Variables,
 
@@ -135,6 +141,8 @@ func (c *Context) GraphBuilder() GraphBuilder {
 		Providers:    providers,
 		Provisioners: provisioners,
 		State:        c.state,
+		Targets:      c.targets,
+		Destroy:      c.destroy,
 	}
 }
 
@@ -253,7 +261,7 @@ func (c *Context) Apply() (*State, error) {
 //
 // Plan also updates the diff of this context to be the diff generated
 // by the plan, so Apply can be called after.
-func (c *Context) Plan(opts *PlanOpts) (*Plan, error) {
+func (c *Context) Plan() (*Plan, error) {
 	v := c.acquireRun()
 	defer c.releaseRun(v)
 
@@ -264,7 +272,7 @@ func (c *Context) Plan(opts *PlanOpts) (*Plan, error) {
 	}
 
 	var operation walkOperation
-	if opts != nil && opts.Destroy {
+	if c.destroy {
 		operation = walkPlanDestroy
 	} else {
 		// Set our state to be something temporary. We do this so that

terraform/graph_builder.go

@@ -65,6 +65,13 @@ type BuiltinGraphBuilder struct {
 
 	// Provisioners is the list of provisioners supported.
 	Provisioners []string
+
+	// Targets is the user-specified list of resources to target.
+	Targets []string
+
+	// Destroy is set to true when we're in a `terraform destroy` or a
+	// `terraform plan -destroy`
+	Destroy bool
 }
 
 // Build builds the graph according to the steps returned by Steps.
@@ -82,7 +89,11 @@ func (b *BuiltinGraphBuilder) Steps() []GraphTransformer {
 	return []GraphTransformer{
 		// Create all our resources from the configuration and state
 		&ConfigTransformer{Module: b.Root},
-		&OrphanTransformer{State: b.State, Module: b.Root},
+		&OrphanTransformer{
+			State:     b.State,
+			Module:    b.Root,
+			Targeting: (len(b.Targets) > 0),
+		},
 
 		// Provider-related transformations
 		&MissingProviderTransformer{Providers: b.Providers},
@@ -104,6 +115,10 @@ func (b *BuiltinGraphBuilder) Steps() []GraphTransformer {
 			},
 		},
 
+		// Optionally reduces the graph to a user-specified list of targets and
+		// their dependencies.
+		&TargetsTransformer{Targets: b.Targets, Destroy: b.Destroy},
+
 		// Create the destruction nodes
 		&DestroyTransformer{},
 		&CreateBeforeDestroyTransformer{},

terraform/graph_config_node.go

@@ -21,6 +21,26 @@ type graphNodeConfig interface {
 	GraphNodeDependent
 }
 
+// GraphNodeAddressable is an interface that all graph nodes for the
+// configuration graph need to implement in order to be be addressed / targeted
+// properly.
+type GraphNodeAddressable interface {
+	graphNodeConfig
+
+	ResourceAddress() *ResourceAddress
+}
+
+// GraphNodeTargetable is an interface for graph nodes to implement when they
+// need to be told about incoming targets. This is useful for nodes that need
+// to respect targets as they dynamically expand. Note that the list of targets
+// provided will contain every target provided, and each implementing graph
+// node must filter this list to targets considered relevant.
+type GraphNodeTargetable interface {
+	GraphNodeAddressable
+
+	SetTargets([]ResourceAddress)
+}
+
 // GraphNodeConfigModule represents a module within the configuration graph.
 type GraphNodeConfigModule struct {
 	Path   []string
@@ -191,6 +211,9 @@ type GraphNodeConfigResource struct {
 	// If this is set to anything other than destroyModeNone, then this
 	// resource represents a resource that will be destroyed in some way.
 	DestroyMode GraphNodeDestroyMode
+
+	// Used during DynamicExpand to target indexes
+	Targets []ResourceAddress
 }
 
 func (n *GraphNodeConfigResource) DependableName() []string {
@@ -279,6 +302,7 @@ func (n *GraphNodeConfigResource) DynamicExpand(ctx EvalContext) (*Graph, error)
 		steps = append(steps, &ResourceCountTransformer{
 			Resource: n.Resource,
 			Destroy:  n.DestroyMode != DestroyNone,
+			Targets:  n.Targets,
 		})
 	}
 
@@ -289,8 +313,9 @@ func (n *GraphNodeConfigResource) DynamicExpand(ctx EvalContext) (*Graph, error)
 		// expand orphans, which have all the same semantics in a destroy
 		// as a primary.
 		steps = append(steps, &OrphanTransformer{
-			State: state,
-			View:  n.Resource.Id(),
+			State:     state,
+			View:      n.Resource.Id(),
+			Targeting: (len(n.Targets) > 0),
 		})
 
 		steps = append(steps, &DeposedTransformer{
@@ -314,6 +339,22 @@ func (n *GraphNodeConfigResource) DynamicExpand(ctx EvalContext) (*Graph, error)
 	return b.Build(ctx.Path())
 }
 
+// GraphNodeAddressable impl.
+func (n *GraphNodeConfigResource) ResourceAddress() *ResourceAddress {
+	return &ResourceAddress{
+		// Indicates no specific index; will match on other three fields
+		Index:        -1,
+		InstanceType: TypePrimary,
+		Name:         n.Resource.Name,
+		Type:         n.Resource.Type,
+	}
+}
+
+// GraphNodeTargetable impl.
+func (n *GraphNodeConfigResource) SetTargets(targets []ResourceAddress) {
+	n.Targets = targets
+}
+
 // GraphNodeEvalable impl.
 func (n *GraphNodeConfigResource) EvalTree() EvalNode {
 	return &EvalSequence{

terraform/instancetype.go

@@ -0,0 +1,13 @@
+package terraform
+
+//go:generate stringer -type=InstanceType instancetype.go
+
+// InstanceType is an enum of the various types of instances store in the State
+type InstanceType int
+
+const (
+	TypeInvalid InstanceType = iota
+	TypePrimary
+	TypeTainted
+	TypeDeposed
+)

terraform/instancetype_string.go

@@ -0,0 +1,16 @@
+// generated by stringer -type=InstanceType instancetype.go; DO NOT EDIT
+
+package terraform
+
+import "fmt"
+
+const _InstanceType_name = "TypeInvalidTypePrimaryTypeTaintedTypeDeposed"
+
+var _InstanceType_index = [...]uint8{0, 11, 22, 33, 44}
+
+func (i InstanceType) String() string {
+	if i < 0 || i+1 >= InstanceType(len(_InstanceType_index)) {
+		return fmt.Sprintf("InstanceType(%d)", i)
+	}
+	return _InstanceType_name[_InstanceType_index[i]:_InstanceType_index[i+1]]
+}

terraform/plan.go

@@ -18,15 +18,6 @@ func init() {
 	gob.Register(make(map[string]string))
 }
 
-// PlanOpts are the options used to generate an execution plan for
-// Terraform.
-type PlanOpts struct {
-	// If set to true, then the generated plan will destroy all resources
-	// that are created. Otherwise, it will move towards the desired state
-	// specified in the configuration.
-	Destroy bool
-}
-
 // Plan represents a single Terraform execution plan, which contains
 // all the information necessary to make an infrastructure change.
 type Plan struct {

terraform/resource_address.go

@@ -0,0 +1,98 @@
+package terraform
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+)
+
+// ResourceAddress is a way of identifying an individual resource (or,
+// eventually, a subset of resources) within the state. It is used for Targets.
+type ResourceAddress struct {
+	Index        int
+	InstanceType InstanceType
+	Name         string
+	Type         string
+}
+
+func ParseResourceAddress(s string) (*ResourceAddress, error) {
+	matches, err := tokenizeResourceAddress(s)
+	if err != nil {
+		return nil, err
+	}
+	resourceIndex := -1
+	if matches["index"] != "" {
+		var err error
+		if resourceIndex, err = strconv.Atoi(matches["index"]); err != nil {
+			return nil, err
+		}
+	}
+	instanceType := TypePrimary
+	if matches["instance_type"] != "" {
+		var err error
+		if instanceType, err = ParseInstanceType(matches["instance_type"]); err != nil {
+			return nil, err
+		}
+	}
+
+	return &ResourceAddress{
+		Index:        resourceIndex,
+		InstanceType: instanceType,
+		Name:         matches["name"],
+		Type:         matches["type"],
+	}, nil
+}
+
+func (addr *ResourceAddress) Equals(raw interface{}) bool {
+	other, ok := raw.(*ResourceAddress)
+	if !ok {
+		return false
+	}
+
+	indexMatch := (addr.Index == -1 ||
+		other.Index == -1 ||
+		addr.Index == other.Index)
+
+	return (indexMatch &&
+		addr.InstanceType == other.InstanceType &&
+		addr.Name == other.Name &&
+		addr.Type == other.Type)
+}
+
+func ParseInstanceType(s string) (InstanceType, error) {
+	switch s {
+	case "primary":
+		return TypePrimary, nil
+	case "deposed":
+		return TypeDeposed, nil
+	case "tainted":
+		return TypeTainted, nil
+	default:
+		return TypeInvalid, fmt.Errorf("Unexpected value for InstanceType field: %q", s)
+	}
+}
+
+func tokenizeResourceAddress(s string) (map[string]string, error) {
+	// Example of portions of the regexp below using the
+	// string "aws_instance.web.tainted[1]"
+	re := regexp.MustCompile(`\A` +
+		// "aws_instance"
+		`(?P<type>\w+)\.` +
+		// "web"
+		`(?P<name>\w+)` +
+		// "tainted" (optional, omission implies: "primary")
+		`(?:\.(?P<instance_type>\w+))?` +
+		// "1" (optional, omission implies: "0")
+		`(?:\[(?P<index>\d+)\])?` +
+		`\z`)
+	groupNames := re.SubexpNames()
+	rawMatches := re.FindAllStringSubmatch(s, -1)
+	if len(rawMatches) != 1 {
+		return nil, fmt.Errorf("Problem parsing address: %q", s)
+	}
+	matches := make(map[string]string)
+	for i, m := range rawMatches[0] {
+		matches[groupNames[i]] = m
+	}
+	return matches, nil
+}

terraform/resource_address_test.go

@@ -0,0 +1,207 @@
+package terraform
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestParseResourceAddress(t *testing.T) {
+	cases := map[string]struct {
+		Input    string
+		Expected *ResourceAddress
+	}{
+		"implicit primary, no specific index": {
+			Input: "aws_instance.foo",
+			Expected: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        -1,
+			},
+		},
+		"implicit primary, explicit index": {
+			Input: "aws_instance.foo[2]",
+			Expected: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        2,
+			},
+		},
+		"explicit primary, explicit index": {
+			Input: "aws_instance.foo.primary[2]",
+			Expected: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        2,
+			},
+		},
+		"tainted": {
+			Input: "aws_instance.foo.tainted",
+			Expected: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypeTainted,
+				Index:        -1,
+			},
+		},
+		"deposed": {
+			Input: "aws_instance.foo.deposed",
+			Expected: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypeDeposed,
+				Index:        -1,
+			},
+		},
+	}
+
+	for tn, tc := range cases {
+		out, err := ParseResourceAddress(tc.Input)
+		if err != nil {
+			t.Fatalf("unexpected err: %#v", err)
+		}
+
+		if !reflect.DeepEqual(out, tc.Expected) {
+			t.Fatalf("bad: %q\n\nexpected:\n%#v\n\ngot:\n%#v", tn, tc.Expected, out)
+		}
+	}
+}
+
+func TestResourceAddressEquals(t *testing.T) {
+	cases := map[string]struct {
+		Address *ResourceAddress
+		Other   interface{}
+		Expect  bool
+	}{
+		"basic match": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Expect: true,
+		},
+		"address does not set index": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        -1,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        3,
+			},
+			Expect: true,
+		},
+		"other does not set index": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        3,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        -1,
+			},
+			Expect: true,
+		},
+		"neither sets index": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        -1,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        -1,
+			},
+			Expect: true,
+		},
+		"different type": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_vpc",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Expect: false,
+		},
+		"different name": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "bar",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Expect: false,
+		},
+		"different instance type": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypeTainted,
+				Index:        0,
+			},
+			Expect: false,
+		},
+		"different index": {
+			Address: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        0,
+			},
+			Other: &ResourceAddress{
+				Type:         "aws_instance",
+				Name:         "foo",
+				InstanceType: TypePrimary,
+				Index:        1,
+			},
+			Expect: false,
+		},
+	}
+
+	for tn, tc := range cases {
+		actual := tc.Address.Equals(tc.Other)
+		if actual != tc.Expect {
+			t.Fatalf("%q: expected equals: %t, got %t for:\n%#v\n%#v",
+				tn, tc.Expect, actual, tc.Address, tc.Other)
+		}
+	}
+}

terraform/test-fixtures/apply-targeted-count/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "foo" {
+  count = 3
+}
+
+resource "aws_instance" "bar" {
+  count = 3
+}

terraform/test-fixtures/apply-targeted/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "foo" {
+    num = "2"
+}
+
+resource "aws_instance" "bar" {
+    foo = "bar"
+}

terraform/test-fixtures/plan-targeted/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "foo" {
+    num = "2"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.num}"
+}

terraform/test-fixtures/refresh-targeted-count/main.tf

@@ -0,0 +1,9 @@
+resource "aws_vpc" "metoo" {}
+resource "aws_instance" "notme" { }
+resource "aws_instance" "me" {
+  vpc_id = "${aws_vpc.metoo.id}"
+  count = 3
+}
+resource "aws_elb" "meneither" {
+  instances = ["${aws_instance.me.*.id}"]
+}

terraform/test-fixtures/refresh-targeted/main.tf

@@ -0,0 +1,8 @@
+resource "aws_vpc" "metoo" {}
+resource "aws_instance" "notme" { }
+resource "aws_instance" "me" {
+  vpc_id = "${aws_vpc.metoo.id}"
+}
+resource "aws_elb" "meneither" {
+  instances = ["${aws_instance.me.*.id}"]
+}

terraform/test-fixtures/transform-targets-basic/main.tf

@@ -0,0 +1,16 @@
+resource "aws_vpc" "me" {}
+
+resource "aws_subnet" "me" {
+  vpc_id = "${aws_vpc.me.id}"
+}
+
+resource "aws_instance" "me" {
+  subnet_id = "${aws_subnet.me.id}"
+}
+
+resource "aws_vpc" "notme" {}
+resource "aws_subnet" "notme" {}
+resource "aws_instance" "notme" {}
+resource "aws_instance" "notmeeither" {
+  name = "${aws_instance.me.id}"
+}

terraform/test-fixtures/transform-targets-destroy/main.tf

@@ -0,0 +1,18 @@
+resource "aws_vpc" "notme" {}
+
+resource "aws_subnet" "notme" {
+  vpc_id = "${aws_vpc.notme.id}"
+}
+
+resource "aws_instance" "me" {
+  subnet_id = "${aws_subnet.notme.id}"
+}
+
+resource "aws_instance" "notme" {}
+resource "aws_instance" "metoo" {
+  name = "${aws_instance.me.id}"
+}
+
+resource "aws_elb" "me" {
+  instances = "${aws_instance.me.*.id}"
+}

terraform/transform_orphan.go

@@ -2,6 +2,7 @@ package terraform
 
 import (
 	"fmt"
+	"log"
 
 	"github.com/hashicorp/terraform/config"
 	"github.com/hashicorp/terraform/config/module"
@@ -25,6 +26,11 @@ type OrphanTransformer struct {
 	// using the graph path.
 	Module *module.Tree
 
+	// Targets are user-specified resources to target. We need to be aware of
+	// these so we don't improperly identify orphans when they've just been
+	// filtered out of the graph via targeting.
+	Targeting bool
+
 	// View, if non-nil will set a view on the module state.
 	View string
 }
@@ -35,6 +41,13 @@ func (t *OrphanTransformer) Transform(g *Graph) error {
 		return nil
 	}
 
+	if t.Targeting {
+		log.Printf("Skipping orphan transformer because we have targets.")
+		// If we are in a run where we are targeting nodes, we won't process
+		// orphans for this run.
+		return nil
+	}
+
 	// Build up all our state representatives
 	resourceRep := make(map[string]struct{})
 	for _, v := range g.Vertices() {

terraform/transform_resource.go

@@ -12,6 +12,7 @@ import (
 type ResourceCountTransformer struct {
 	Resource *config.Resource
 	Destroy  bool
+	Targets  []ResourceAddress
 }
 
 func (t *ResourceCountTransformer) Transform(g *Graph) error {
@@ -27,7 +28,7 @@ func (t *ResourceCountTransformer) Transform(g *Graph) error {
 	}
 
 	// For each count, build and add the node
-	nodes := make([]dag.Vertex, count)
+	nodes := make([]dag.Vertex, 0, count)
 	for i := 0; i < count; i++ {
 		// Set the index. If our count is 1 we special case it so that
 		// we handle the "resource.0" and "resource" boundary properly.
@@ -49,9 +50,14 @@ func (t *ResourceCountTransformer) Transform(g *Graph) error {
 			}
 		}
 
+		// Skip nodes if targeting excludes them
+		if !t.nodeIsTargeted(node) {
+			continue
+		}
+
 		// Add the node now
-		nodes[i] = node
-		g.Add(nodes[i])
+		nodes = append(nodes, node)
+		g.Add(node)
 	}
 
 	// Make the dependency connections
@@ -64,6 +70,25 @@ func (t *ResourceCountTransformer) Transform(g *Graph) error {
 	return nil
 }
 
+func (t *ResourceCountTransformer) nodeIsTargeted(node dag.Vertex) bool {
+	// no targets specified, everything stays in the graph
+	if len(t.Targets) == 0 {
+		return true
+	}
+	addressable, ok := node.(GraphNodeAddressable)
+	if !ok {
+		return false
+	}
+
+	addr := addressable.ResourceAddress()
+	for _, targetAddr := range t.Targets {
+		if targetAddr.Equals(addr) {
+			return true
+		}
+	}
+	return false
+}
+
 type graphNodeExpandedResource struct {
 	Index    int
 	Resource *config.Resource
@@ -77,6 +102,23 @@ func (n *graphNodeExpandedResource) Name() string {
 	return fmt.Sprintf("%s #%d", n.Resource.Id(), n.Index)
 }
 
+// GraphNodeAddressable impl.
+func (n *graphNodeExpandedResource) ResourceAddress() *ResourceAddress {
+	// We want this to report the logical index properly, so we must undo the
+	// special case from the expand
+	index := n.Index
+	if index == -1 {
+		index = 0
+	}
+	return &ResourceAddress{
+		Index: index,
+		// TODO: kjkjkj
+		InstanceType: TypePrimary,
+		Name:         n.Resource.Name,
+		Type:         n.Resource.Type,
+	}
+}
+
 // GraphNodeDependable impl.
 func (n *graphNodeExpandedResource) DependableName() []string {
 	return []string{

terraform/transform_targets.go

@@ -0,0 +1,103 @@
+package terraform
+
+import "github.com/hashicorp/terraform/dag"
+
+// TargetsTransformer is a GraphTransformer that, when the user specifies a
+// list of resources to target, limits the graph to only those resources and
+// their dependencies.
+type TargetsTransformer struct {
+	// List of targeted resource names specified by the user
+	Targets []string
+
+	// Set to true when we're in a `terraform destroy` or a
+	// `terraform plan -destroy`
+	Destroy bool
+}
+
+func (t *TargetsTransformer) Transform(g *Graph) error {
+	if len(t.Targets) > 0 {
+		// TODO: duplicated in OrphanTransformer; pull up parsing earlier
+		addrs, err := t.parseTargetAddresses()
+		if err != nil {
+			return err
+		}
+
+		targetedNodes, err := t.selectTargetedNodes(g, addrs)
+		if err != nil {
+			return err
+		}
+
+		for _, v := range g.Vertices() {
+			if targetedNodes.Include(v) {
+			} else {
+				g.Remove(v)
+			}
+		}
+	}
+	return nil
+}
+
+func (t *TargetsTransformer) parseTargetAddresses() ([]ResourceAddress, error) {
+	addrs := make([]ResourceAddress, len(t.Targets))
+	for i, target := range t.Targets {
+		ta, err := ParseResourceAddress(target)
+		if err != nil {
+			return nil, err
+		}
+		addrs[i] = *ta
+	}
+	return addrs, nil
+}
+
+func (t *TargetsTransformer) selectTargetedNodes(
+	g *Graph, addrs []ResourceAddress) (*dag.Set, error) {
+	targetedNodes := new(dag.Set)
+	for _, v := range g.Vertices() {
+		// Keep all providers; they'll be pruned later if necessary
+		if r, ok := v.(GraphNodeProvider); ok {
+			targetedNodes.Add(r)
+			continue
+		}
+
+		// For the remaining filter, we only care about addressable nodes
+		r, ok := v.(GraphNodeAddressable)
+		if !ok {
+			continue
+		}
+
+		if t.nodeIsTarget(r, addrs) {
+			targetedNodes.Add(r)
+			// If the node would like to know about targets, tell it.
+			if n, ok := r.(GraphNodeTargetable); ok {
+				n.SetTargets(addrs)
+			}
+
+			var deps *dag.Set
+			var err error
+			if t.Destroy {
+				deps, err = g.Descendents(r)
+			} else {
+				deps, err = g.Ancestors(r)
+			}
+			if err != nil {
+				return nil, err
+			}
+
+			for _, d := range deps.List() {
+				targetedNodes.Add(d)
+			}
+		}
+	}
+	return targetedNodes, nil
+}
+
+func (t *TargetsTransformer) nodeIsTarget(
+	r GraphNodeAddressable, addrs []ResourceAddress) bool {
+	addr := r.ResourceAddress()
+	for _, targetAddr := range addrs {
+		if targetAddr.Equals(addr) {
+			return true
+		}
+	}
+	return false
+}

terraform/transform_targets_test.go

@@ -0,0 +1,71 @@
+package terraform
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestTargetsTransformer(t *testing.T) {
+	mod := testModule(t, "transform-targets-basic")
+
+	g := Graph{Path: RootModulePath}
+	{
+		tf := &ConfigTransformer{Module: mod}
+		if err := tf.Transform(&g); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	}
+
+	{
+		transform := &TargetsTransformer{Targets: []string{"aws_instance.me"}}
+		if err := transform.Transform(&g); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(`
+aws_instance.me
+  aws_subnet.me
+aws_subnet.me
+  aws_vpc.me
+aws_vpc.me
+	`)
+	if actual != expected {
+		t.Fatalf("bad:\n\nexpected:\n%s\n\ngot:\n%s\n", expected, actual)
+	}
+}
+
+func TestTargetsTransformer_destroy(t *testing.T) {
+	mod := testModule(t, "transform-targets-destroy")
+
+	g := Graph{Path: RootModulePath}
+	{
+		tf := &ConfigTransformer{Module: mod}
+		if err := tf.Transform(&g); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	}
+
+	{
+		transform := &TargetsTransformer{
+			Targets: []string{"aws_instance.me"},
+			Destroy: true,
+		}
+		if err := transform.Transform(&g); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(`
+aws_elb.me
+  aws_instance.me
+aws_instance.me
+aws_instance.metoo
+  aws_instance.me
+	`)
+	if actual != expected {
+		t.Fatalf("bad:\n\nexpected:\n%s\n\ngot:\n%s\n", expected, actual)
+	}
+}

website/source/docs/commands/apply.html.markdown

@@ -44,6 +44,11 @@ The command-line flags are all optional. The list of available flags are:
 * `-state-out=path` - Path to write updated state file. By default, the
   `-state` path will be used.
 
+* `-target=resource` - A [Resource
+  Address](/docs/internals/resource-addressing.html) to target. Operation will
+  be limited to this resource and its dependencies. This flag can be used
+  multiple times.
+
 * `-var 'foo=bar'` - Set a variable in the Terraform configuration. This
   flag can be set multiple times.
 

website/source/docs/commands/destroy.html.markdown

@@ -21,3 +21,9 @@ confirmation before destroying.
 This command accepts all the flags that the
 [apply command](/docs/commands/apply.html) accepts. If `-force` is
 set, then the destroy confirmation will not be shown.
+
+The `-target` flag, instead of affecting "dependencies" will instead also
+destroy any resources that _depend on_ the target(s) specified.
+
+The behavior of any `terraform destroy` command can be previewed at any time
+with an equivalent `terraform plan -destroy` command.

website/source/docs/commands/plan.html.markdown

@@ -45,6 +45,11 @@ The command-line flags are all optional. The list of available flags are:
 
 * `-state=path` - Path to the state file. Defaults to "terraform.tfstate".
 
+* `-target=resource` - A [Resource
+  Address](/docs/internals/resource-addressing.html) to target. Operation will
+  be limited to this resource and its dependencies. This flag can be used
+  multiple times.
+
 * `-var 'foo=bar'` - Set a variable in the Terraform configuration. This
   flag can be set multiple times.
 

website/source/docs/commands/refresh.html.markdown

@@ -36,6 +36,11 @@ The command-line flags are all optional. The list of available flags are:
 * `-state-out=path` - Path to write updated state file. By default, the
   `-state` path will be used.
 
+* `-target=resource` - A [Resource
+  Address](/docs/internals/resource-addressing.html) to target. Operation will
+  be limited to this resource and its dependencies. This flag can be used
+  multiple times.
+
 * `-var 'foo=bar'` - Set a variable in the Terraform configuration. This
   flag can be set multiple times.
 

website/source/docs/internals/resource-addressing.html.markdown

@@ -0,0 +1,57 @@
+---
+layout: "docs"
+page_title: "Internals: Resource Address"
+sidebar_current: "docs-internals-resource-addressing"
+description: |-
+  Resource addressing is used to target specific resources in a larger
+  infrastructure.
+---
+
+# Resource Addressing
+
+A __Resource Address__ is a string that references a specific resource in a
+larger infrastructure. The syntax of a resource address is:
+
+```
+<resource_type>.<resource_name>[optional fields]
+```
+
+Required fields:
+
+ * `resource_type` - Type of the resource being addressed.
+ * `resource_name` - User-defined name of the resource.
+
+Optional fields may include:
+
+ * `[N]` - where `N` is a `0`-based index into a resource with multiple
+   instances specified by the `count` meta-parameter. Omitting an index when
+   addressing a resource where `count > 1` means that the address references
+   all instances.
+
+
+## Examples
+
+Given a Terraform config that includes:
+
+```
+resource "aws_instance" "web" {
+  # ...
+  count = 4
+}
+```
+
+An address like this:
+
+
+```
+aws_instance.web[3]
+```
+
+Refers to only the last instance in the config, and an address like this:
+
+```
+aws_instance.web
+```
+
+
+Refers to all four "web" instances.

website/source/layouts/docs.erb

@@ -219,6 +219,10 @@
 					<li<%= sidebar_current("docs-internals-lifecycle") %>>
 					<a href="/docs/internals/lifecycle.html">Resource Lifecycle</a>
 					</li>
+
+					<li<%= sidebar_current("docs-internals-resource-addressing") %>>
+					<a href="/docs/internals/resource-addressing.html">Resource Addressing</a>
+					</li>
 				</ul>
 				</li>
 			</ul>