aws_autoscaling_policy: Add documentation for StepScaling policies.

Author: ctiwald

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

@@ -44,10 +44,54 @@ The following arguments are supported:
 
 * `name` - (Required) The name of the policy.
 * `autoscaling_group_name` - (Required) The name or ARN of the group.
-* `adjustment_type` - (Required) Specifies whether the `scaling_adjustment` is an absolute number or a percentage of the current capacity. Valid values are `ChangeInCapacity`, `ExactCapacity`, and `PercentChangeInCapacity`.
-* `scaling_adjustment` - (Required) The number of instances by which to scale. `adjustment_type` determines the interpretation of this number (e.g., as an absolute number or as a percentage of the existing Auto Scaling group size). A positive increment adds to the current capacity and a negative value removes from the current capacity.
+* `adjustment_type` - (Required) Specifies whether the adjustment is an absolute number or a percentage of the current capacity. Valid values are `ChangeInCapacity`, `ExactCapacity`, and `PercentChangeInCapacity`.
+* `policy_type` - (Optional) The policy type, either "SimpleScaling" or "StepScaling". If this value isn't provided, AWS will default to "SimpleScaling."
+
+The following arguments are only available to "SimpleScaling" type policies:
+
 * `cooldown` - (Optional) The amount of time, in seconds, after a scaling activity completes and before the next scaling activity can start.
-* `min_adjustment_step` - (Optional) Used with `adjustment_type` with the value `PercentChangeInCapacity`, the scaling policy changes the `desired_capacity` of the Auto Scaling group by at least the number of instances specified in the value.
+* `scaling_adjustment` - (Optional) The number of instances by which to scale. `adjustment_type` determines the interpretation of this number (e.g., as an absolute number or as a percentage of the existing Auto Scaling group size). A positive increment adds to the current capacity and a negative value removes from the current capacity.
+
+The following arguments are only available to "StepScaling" type policies:
+
+* `metric_aggregation_type` - (Optional) The aggregation type for the policy's metrics. Valid values are "Minimum", "Maximum", and "Average". Without a value, AWS will treat the aggregation type as "Average".
+* `estimated_instance_warmup` - (Optional) The estimated time, in seconds, until a newly launched instance will contribute CloudWatch metrics. Without a value, AWS will default to the group's specified cooldown period.
+* `step_adjustments` - (Optional) A set of adjustments that manage
+group scaling. These have the following structure:
+
+```
+step_adjustment {
+  scaling_adjustment = -1
+  metric_interval_lower_bound = 1.0
+  metric_interval_upper_bound = 2.0
+}
+step_adjustment {
+  scaling_adjustment = 1
+  metric_interval_lower_bound = 2.0
+  metric_interval_upper_bound = 3.0
+}
+```
+
+The following fields are available in step adjustments:
+
+* `scaling_adjustment` - (Required) The number of members by which to
+scale, when the adjustment bounds are breached. A positive value scales
+up. A negative value scales down.
+* `metric_interval_lower_bound` - (Optional) The lower bound for the
+difference between the alarm threshold and the CloudWatch metric.
+Without a value, AWS will treat this bound as infinity.
+* `metric_interval_upper_bound` - (Optional) The upper bound for the
+difference between the alarm threshold and the CloudWatch metric.
+Without a value, AWS will treat this bound as infinity. The upper bound
+must be greater than the lower bound.
+
+The following arguments are supported for backwards compatibility but should not be used:
+
+* `min_adjustment_step` - (Optional) Use `min_adjustment_magnitude` instead.
 
 ## Attribute Reference
 * `arn` - The ARN assigned by AWS to the scaling policy.
+* `name` - The scaling policy's name.
+* `autoscaling_group_name` - The scaling policy's assigned autoscaling group.
+* `adjustment_type` - The scaling policy's adjustment type.
+* `policy_type` - The scaling policy's type.