command/apply: show add/remove/change count for apply

command/apply.go

@@ -50,6 +50,10 @@ func (c *ApplyCommand) Run(args []string) int {
 		}
 	}
 
+	// Prepare the extra hooks to count resources
+	countHook := new(CountHook)
+	c.Meta.extraHooks = []terraform.Hook{countHook}
+
 	// If we don't specify an output path, default to out normal state
 	// path.
 	if stateOutPath == "" {
@@ -124,13 +128,21 @@ func (c *ApplyCommand) Run(args []string) int {
 
 	c.Ui.Output(c.Colorize().Color(fmt.Sprintf(
 		"[reset][bold][green]\n"+
-			"Apply succeeded! Infrastructure created and/or updated.\n"+
-			"The state of your infrastructure has been saved to the path\n"+
-			"below. This state is required to modify and destroy your\n"+
-			"infrastructure, so keep it safe. To inspect the complete state\n"+
-			"use the `terraform show` command.\n\n"+
-			"State path: %s",
-		stateOutPath)))
+			"Apply complete! Resources: %d added, %d changed, %d destroyed.",
+		countHook.Added,
+		countHook.Changed,
+		countHook.Removed)))
+
+	if countHook.Added > 0 || countHook.Changed > 0 {
+		c.Ui.Output(c.Colorize().Color(fmt.Sprintf(
+			"[reset]\n"+
+				"The state of your infrastructure has been saved to the path\n"+
+				"below. This state is required to modify and destroy your\n"+
+				"infrastructure, so keep it safe. To inspect the complete state\n"+
+				"use the `terraform show` command.\n\n"+
+				"State path: %s",
+			stateOutPath)))
+	}
 
 	// If we have outputs, then output those at the end.
 	if len(state.Outputs) > 0 {

command/hook_count.go

@@ -0,0 +1,83 @@
+package command
+
+import (
+	"sync"
+
+	"github.com/hashicorp/terraform/terraform"
+)
+
+// CountHook is a hook that counts the number of resources
+// added, removed, changed during the course of an apply.
+type CountHook struct {
+	Added   int
+	Changed int
+	Removed int
+
+	pending map[string]countHookAction
+
+	sync.Mutex
+	terraform.NilHook
+}
+
+type countHookAction byte
+
+const (
+	countHookActionAdd countHookAction = iota
+	countHookActionChange
+	countHookActionRemove
+)
+
+func (h *CountHook) Reset() {
+	h.Lock()
+	defer h.Unlock()
+
+	h.pending = nil
+	h.Added = 0
+	h.Changed = 0
+	h.Removed = 0
+}
+
+func (h *CountHook) PreApply(
+	id string,
+	s *terraform.ResourceState,
+	d *terraform.ResourceDiff) (terraform.HookAction, error) {
+	h.Lock()
+	defer h.Unlock()
+
+	if h.pending == nil {
+		h.pending = make(map[string]countHookAction)
+	}
+
+	action := countHookActionChange
+	if d.Destroy {
+		action = countHookActionRemove
+	} else if s.ID == "" {
+		action = countHookActionAdd
+	}
+
+	h.pending[id] = action
+
+	return terraform.HookActionContinue, nil
+}
+
+func (h *CountHook) PostApply(
+	id string,
+	s *terraform.ResourceState) (terraform.HookAction, error) {
+	h.Lock()
+	defer h.Unlock()
+
+	if h.pending != nil {
+		if a, ok := h.pending[id]; ok {
+			switch a {
+			case countHookActionAdd:
+				h.Added += 1
+			case countHookActionChange:
+				h.Changed += 1
+			case countHookActionRemove:
+				h.Removed += 1
+			}
+		}
+	}
+
+	return terraform.HookActionContinue, nil
+}

command/hook_count_test.go

@@ -0,0 +1,11 @@
+package command
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform/terraform"
+)
+
+func TestCountHook_impl(t *testing.T) {
+	var _ terraform.Hook = new(CountHook)
+}

command/meta.go

@@ -16,6 +16,9 @@ type Meta struct {
 	ContextOpts *terraform.ContextOpts
 	Ui          cli.Ui
 
+	// This can be set by the command itself to provide extra hooks.
+	extraHooks []terraform.Hook
+
 	color bool
 	oldUi cli.Ui
 }
@@ -99,9 +102,13 @@ func (m *Meta) Context(path, statePath string, doPlan bool) (*terraform.Context,
 // context with the settings from this Meta.
 func (m *Meta) contextOpts() *terraform.ContextOpts {
 	var opts terraform.ContextOpts = *m.ContextOpts
-	opts.Hooks = make([]terraform.Hook, len(m.ContextOpts.Hooks)+1)
+	opts.Hooks = make(
+		[]terraform.Hook,
+		len(m.ContextOpts.Hooks)+len(m.extraHooks)+1)
 	opts.Hooks[0] = m.uiHook()
 	copy(opts.Hooks[1:], m.ContextOpts.Hooks)
+	copy(opts.Hooks[len(m.ContextOpts.Hooks)+1:], m.extraHooks)
+	println(fmt.Sprintf("%#v", opts.Hooks))
 	return &opts
 }