provider/aws: allow empty value for autoscaling schedule parameters

Specifically, this allows you to create a schedule which only changes
some of the group parameters without changing others, by setting the
parameters you wish to remain empty to -1.  This means you can adjust
min or max size without affecting the desired capacity, for example.

The ad hoc support for -1 isn't as nice as having real support for
leaving values out (see hashicorp#5694) but it solves a real use case.

Fixes hashicorp#5681.

builtin/providers/aws/resource_aws_autoscaling_schedule.go

@@ -97,9 +97,24 @@ func resourceAwsAutoscalingScheduleCreate(d *schema.ResourceData, meta interface
  params.Recurrence = aws.String(attr.(string))
  }
 
- params.MinSize = aws.Int64(int64(d.Get("min_size").(int)))
- params.MaxSize = aws.Int64(int64(d.Get("max_size").(int)))
- params.DesiredCapacity = aws.Int64(int64(d.Get("desired_capacity").(int)))
+ // Scheduled actions don't need to set all three size parameters. For example,
+ // you may want to change the min or max without also forcing an immediate
+ // resize by changing a desired_capacity that may have changed due to other
+ // autoscaling rules. Since Terraform doesn't have a great pattern for
+ // differentiating between 0 and unset fields, we accept "-1" to mean "don't
+ // include this parameter in the action".
+ minSize := int64(d.Get("min_size").(int))
+ maxSize := int64(d.Get("max_size").(int))
+ desiredCapacity := int64(d.Get("desired_capacity").(int))
+ if minSize != -1 {
+ params.MinSize = aws.Int64(minSize)
+ }
+ if maxSize != -1 {
+ params.MaxSize = aws.Int64(maxSize)
+ }
+ if desiredCapacity != -1 {
+ params.DesiredCapacity = aws.Int64(desiredCapacity)
+ }
 
  log.Printf("[INFO] Creating Autoscaling Scheduled Action: %s", d.Get("scheduled_action_name").(string))
  _, err := autoscalingconn.PutScheduledUpdateGroupAction(params)
@@ -120,9 +135,23 @@ func resourceAwsAutoscalingScheduleRead(d *schema.ResourceData, meta interface{}
 
  d.Set("autoscaling_group_name", sa.AutoScalingGroupName)
  d.Set("arn", sa.ScheduledActionARN)
- d.Set("desired_capacity", sa.DesiredCapacity)
- d.Set("min_size", sa.MinSize)
- d.Set("max_size", sa.MaxSize)
+
+ if sa.MinSize == nil {
+ d.Set("min_size", -1)
+ } else {
+ d.Set("min_size", sa.MinSize)
+ }
+ if sa.MaxSize == nil {
+ d.Set("max_size", -1)
+ } else {
+ d.Set("max_size", sa.MaxSize)
+ }
+ if sa.DesiredCapacity == nil {
+ d.Set("desired_capacity", -1)
+ } else {
+ d.Set("desired_capacity", sa.DesiredCapacity)
+ }
+
  d.Set("recurrence", sa.Recurrence)
 
  if sa.StartTime != nil {

builtin/providers/aws/resource_aws_autoscaling_schedule_test.go

@@ -65,6 +65,26 @@ func TestAccAWSAutoscalingSchedule_zeroValues(t *testing.T) {
  })
 }
 
+func TestAccAWSAutoscalingSchedule_negativeOne(t *testing.T) {
+ var schedule autoscaling.ScheduledUpdateGroupAction
+
+ resource.Test(t, resource.TestCase{
+ PreCheck: func() { testAccPreCheck(t) },
+ Providers: testAccProviders,
+ CheckDestroy: testAccCheckAWSAutoscalingScheduleDestroy,
+ Steps: []resource.TestStep{
+ resource.TestStep{
+ Config: testAccAWSAutoscalingScheduleConfig_negativeOne,
+ Check: resource.ComposeTestCheckFunc(
+ testAccCheckScalingScheduleExists("aws_autoscaling_schedule.foobar", &schedule),
+ testAccCheckScalingScheduleHasNoDesiredCapacity(&schedule),
+ resource.TestCheckResourceAttr("aws_autoscaling_schedule.foobar", "desired_capacity", "-1"),
+ ),
+ },
+ },
+ })
+}
+
 func testAccCheckScalingScheduleExists(n string, policy *autoscaling.ScheduledUpdateGroupAction) resource.TestCheckFunc {
  return func(s *terraform.State) error {
  rs, ok := s.RootModule().Resources[n]
@@ -86,6 +106,7 @@ func testAccCheckScalingScheduleExists(n string, policy *autoscaling.ScheduledUp
  if len(resp.ScheduledUpdateGroupActions) == 0 {
  return fmt.Errorf("Scaling Schedule not found")
  }
+ *policy = *resp.ScheduledUpdateGroupActions[0]
 
  return nil
  }
@@ -118,6 +139,17 @@ func testAccCheckAWSAutoscalingScheduleDestroy(s *terraform.State) error {
  return nil
 }
 
+func testAccCheckScalingScheduleHasNoDesiredCapacity(
+ schedule *autoscaling.ScheduledUpdateGroupAction) resource.TestCheckFunc {
+ return func(s *terraform.State) error {
+ if schedule.DesiredCapacity == nil {
+ return nil
+ }
+ return fmt.Errorf("Expected not to set desired capacity, got %v",
+ aws.Int64Value(schedule.DesiredCapacity))
+ }
+}
+
 var testAccAWSAutoscalingScheduleConfig = fmt.Sprintf(`
 resource "aws_launch_configuration" "foobar" {
  name = "terraform-test-foobar5"
@@ -221,3 +253,38 @@ resource "aws_autoscaling_schedule" "foobar" {
  autoscaling_group_name = "${aws_autoscaling_group.foobar.name}"
 }
 `)
+
+var testAccAWSAutoscalingScheduleConfig_negativeOne = fmt.Sprintf(`
+resource "aws_launch_configuration" "foobar" {
+ name = "terraform-test-foobar5"
+ image_id = "ami-21f78e11"
+ instance_type = "t1.micro"
+}
+
+resource "aws_autoscaling_group" "foobar" {
+ availability_zones = ["us-west-2a"]
+ name = "terraform-test-foobar5"
+ max_size = 1
+ min_size = 1
+ health_check_grace_period = 300
+ health_check_type = "ELB"
+ force_delete = true
+ termination_policies = ["OldestInstance"]
+ launch_configuration = "${aws_launch_configuration.foobar.name}"
+ tag {
+ key = "Foo"
+ value = "foo-bar"
+ propagate_at_launch = true
+ }
+}
+
+resource "aws_autoscaling_schedule" "foobar" {
+ scheduled_action_name = "foobar"
+ max_size = 3
+ min_size = 1
+ desired_capacity = -1
+ start_time = "2018-01-16T07:00:00Z"
+ end_time = "2018-01-16T13:00:00Z"
+ autoscaling_group_name = "${aws_autoscaling_group.foobar.name}"
+}
+`)

website/source/docs/providers/aws/r/autoscaling_schedule.html.markdown

@@ -46,10 +46,10 @@ The following arguments are supported:
  If you try to schedule your action in the past, Auto Scaling returns an error message.
 * `recurrence` - (Optional) The time when recurring future actions will start. Start time is specified by the user following the Unix cron syntax format. 
 * `min_size` - (Optional) The minimum size for the Auto Scaling group. Default
-0.
+0. Set to -1 if you don't want to change the minimum size at the scheduled time.
 * `max_size` - (Optional) The maximum size for the Auto Scaling group. Default
-0.
-* `desired_capacity` - (Optional) The number of EC2 instances that should be running in the group. Default 0.
+0. Set to -1 if you don't want to change the maximum size at the scheduled time.
+* `desired_capacity` - (Optional) The number of EC2 instances that should be running in the group. Default 0. Set to -1 if you don't want to change the desired capacity at the scheduled time.
 
 ~> **NOTE:** When `start_time` and `end_time` are specified with `recurrence` , they form the boundaries of when the recurring action will start and stop.