policy.md

App AutoScaler Policy JSON Specification

App AutoScaler requires a policy file written in JSON with the following schema:

Policy

Name	Type	Required	Description
instance_min_count	int	true	minimal number of instance count
instance_max_count	int	true	maximal number of instance count
scaling_rules	JSON Array<scaling_rules>	AnyOf	dynamic scaling rules, see Scaling Rules below
schedules	JSON Array	AnyOf	scheduled, see Schedules below

Scaling Rules

Name	Type	Required	Description
metric_type	String	true	one of system-default metric types memoryused,memoryutil,responsetime, throughput, cpu or user-defined custom metric type
threshold	int	true	the boundary when metric value exceeds is considered as a breach
operator	String	true	>, <, >=, <=
adjustment	String	true	the adjustment approach for instance count with each scaling. Support regex format ^[-+][1-9]+[0-9]*[%]?$, i.e. +5 means adding 5 instances, -50% means shrinking to the half of current size.
breach_duration_secs	int, seconds	false	time duration to fire scaling event if it keeps breaching
cool_down_secs	int,seconds	false	the time duration to wait before the next scaling kicks in

Schedules

Name	Type	Required	Description
timezone	String	true	Using timezone definition of Java
recurring_schedule	JSON Array<recurring_schedules>	AnyOf	the schedules which will take effect repeatly, see Recurring Schedule below
specific_date	JSON Array<specific_date>	AnyOf	the schedules which take effect only once, see Specific Date below

Recurring Schedule

Name	Type	Required	Description
start_date	String,"yyyy-mm-dd"	false	the start date of the schedule. Must be a future time .
end_date	String,"yyyy-mm-dd"	false	the end date of the schedule. Must be a future time.
start_time	String,"hh:mm"	true	the start time of the schedule
end_time	String,"hh:mm"	true	the end time of the schedule
days_of_week / days_of_month	Array	false	recurring days of a week or month. Use [1,2,..,7] or [1,2,...,31] to define it
instance_min_count	int	true	minimal number of instance count for this schedule
instance_max_count	int	true	maximal number of instance count for this schedule
initial_min_instance_count	int	false	the initial minimal number of instance count for this schedule

Specific Date

Name	Type	Required	Description
start_date_time	String,"yyyy-mm-ddThh:mm"	true	the start time of the schedule. Must be a future time
start_date_time	String,"yyyy-mm-ddThh:mm"	true	the end time of the schedule. Must be a future time
instance_min_count	int	true	minimal number of instance count for this schedule
instance_max_count	int	true	maximal number of instance count for this schedule
initial_min_instance_count	int	false	the initial minimal number of instance count for this schedule

Constraints

• If one schedule overlaps another, the one which starts first will be guaranteed, while the later one is completely ignored. For example:

  • Schedule #1: --------sssssssssss----------------------------
  • Schedule #2: ---------------ssssssssssssss-----------------
  • Schedule #3: --------------------------sssssssss------------

  With above definition, schedule #1 and #3 will be applied, while scheudle #2 is ignored.

Sample Policy

• Autoscaling policy with dynamic scaling rules
• Autoscaling policy with dynamic scaling rules defined by custom metrics
• Autoscaling policy with dynamic scaling rules and schedules