terraform: self.count works in interpolations [GH-5283]

terraform/context_apply_test.go

@@ -2405,6 +2405,59 @@ func TestContext2Apply_provisionerMultiSelfRef(t *testing.T) {
 	}
 }
 
+func TestContext2Apply_provisionerMultiSelfRefCount(t *testing.T) {
+	var lock sync.Mutex
+	commands := make([]string, 0, 5)
+
+	m := testModule(t, "apply-provisioner-multi-self-ref-count")
+	p := testProvider("aws")
+	pr := testProvisioner()
+	p.ApplyFn = testApplyFn
+	p.DiffFn = testDiffFn
+	pr.ApplyFn = func(rs *InstanceState, c *ResourceConfig) error {
+		lock.Lock()
+		defer lock.Unlock()
+
+		val, ok := c.Config["command"]
+		if !ok {
+			t.Fatalf("bad value for command: %v %#v", val, c)
+		}
+
+		commands = append(commands, val.(string))
+		return nil
+	}
+
+	ctx := testContext2(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+		Provisioners: map[string]ResourceProvisionerFactory{
+			"shell": testProvisionerFuncFixed(pr),
+		},
+	})
+
+	if _, err := ctx.Plan(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if _, err := ctx.Apply(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Verify apply was invoked
+	if !pr.ApplyCalled {
+		t.Fatalf("provisioner not invoked")
+	}
+
+	// Verify our result
+	sort.Strings(commands)
+	expectedCommands := []string{"3", "3", "3"}
+	if !reflect.DeepEqual(commands, expectedCommands) {
+		t.Fatalf("bad: %#v", commands)
+	}
+}
+
 // Provisioner should NOT run on a diff, only create
 func TestContext2Apply_Provisioner_Diff(t *testing.T) {
 	m := testModule(t, "apply-provisioner-diff")

terraform/interpolate.go

@@ -265,6 +265,7 @@ func (i *Interpolater) valueSelfVar(
 		return fmt.Errorf(
 			"%s: invalid scope, self variables are only valid on resources", n)
 	}
+
 	rv, err := config.NewResourceVariable(fmt.Sprintf(
 		"%s.%s.%d.%s",
 		scope.Resource.Type,
@@ -359,11 +360,25 @@ func (i *Interpolater) computeResourceVariable(
 
 	// Get the information about this resource variable, and verify
 	// that it exists and such.
-	module, _, err := i.resourceVariableInfo(scope, v)
+	module, cr, err := i.resourceVariableInfo(scope, v)
 	if err != nil {
 		return nil, err
 	}
 
+	// If we're requesting "count" its a special variable that we grab
+	// directly from the config itself.
+	if v.Field == "count" {
+		count, err := cr.Count()
+		if err != nil {
+			return nil, fmt.Errorf(
+				"Error reading %s count: %s",
+				v.ResourceId(),
+				err)
+		}
+
+		return &ast.Variable{Type: ast.TypeInt, Value: count}, nil
+	}
+
 	// If we have no module in the state yet or count, return empty
 	if module == nil || len(module.Resources) == 0 {
 		return nil, nil

terraform/test-fixtures/apply-provisioner-multi-self-ref-count/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "foo" {
+    count = 3
+
+    provisioner "shell" {
+        command = "${self.count}"
+    }
+}