This is the new *Amazon CloudFormation Template Reference Guide*. Please update your bookmarks and links. For help getting started with CloudFormation, see the [Amazon CloudFormation User Guide](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/Welcome.html).
# AWS::GameLift::Fleet ScalingPolicy
Rule that controls how a fleet is scaled. Scaling policies are uniquely identified by the combination of name and fleet ID.
## Syntax
To declare this entity in your Amazon CloudFormation template, use the following syntax:
### JSON
```
{
"[ComparisonOperator](#cfn-gamelift-fleet-scalingpolicy-comparisonoperator)" : {{String}},
"[EvaluationPeriods](#cfn-gamelift-fleet-scalingpolicy-evaluationperiods)" : {{Integer}},
"[Location](#cfn-gamelift-fleet-scalingpolicy-location)" : {{String}},
"[MetricName](#cfn-gamelift-fleet-scalingpolicy-metricname)" : {{String}},
"[Name](#cfn-gamelift-fleet-scalingpolicy-name)" : {{String}},
"[PolicyType](#cfn-gamelift-fleet-scalingpolicy-policytype)" : {{String}},
"[ScalingAdjustment](#cfn-gamelift-fleet-scalingpolicy-scalingadjustment)" : {{Integer}},
"[ScalingAdjustmentType](#cfn-gamelift-fleet-scalingpolicy-scalingadjustmenttype)" : {{String}},
"[Status](#cfn-gamelift-fleet-scalingpolicy-status)" : {{String}},
"[TargetConfiguration](#cfn-gamelift-fleet-scalingpolicy-targetconfiguration)" : {{TargetConfiguration}},
"[Threshold](#cfn-gamelift-fleet-scalingpolicy-threshold)" : {{Number}},
"[UpdateStatus](#cfn-gamelift-fleet-scalingpolicy-updatestatus)" : {{String}}
}
```
### YAML
```
[ComparisonOperator](#cfn-gamelift-fleet-scalingpolicy-comparisonoperator): {{String}}
[EvaluationPeriods](#cfn-gamelift-fleet-scalingpolicy-evaluationperiods): {{Integer}}
[Location](#cfn-gamelift-fleet-scalingpolicy-location): {{String}}
[MetricName](#cfn-gamelift-fleet-scalingpolicy-metricname): {{String}}
[Name](#cfn-gamelift-fleet-scalingpolicy-name): {{String}}
[PolicyType](#cfn-gamelift-fleet-scalingpolicy-policytype): {{String}}
[ScalingAdjustment](#cfn-gamelift-fleet-scalingpolicy-scalingadjustment): {{Integer}}
[ScalingAdjustmentType](#cfn-gamelift-fleet-scalingpolicy-scalingadjustmenttype): {{String}}
[Status](#cfn-gamelift-fleet-scalingpolicy-status): {{String}}
[TargetConfiguration](#cfn-gamelift-fleet-scalingpolicy-targetconfiguration): {{
TargetConfiguration}}
[Threshold](#cfn-gamelift-fleet-scalingpolicy-threshold): {{Number}}
[UpdateStatus](#cfn-gamelift-fleet-scalingpolicy-updatestatus): {{String}}
```
## Properties
`ComparisonOperator`
Comparison operator to use when measuring a metric against the threshold value.
*Required*: No
*Type*: String
*Allowed values*: `GreaterThanOrEqualToThreshold | GreaterThanThreshold | LessThanThreshold | LessThanOrEqualToThreshold`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`EvaluationPeriods`
Length of time (in minutes) the metric must be at or beyond the threshold before a scaling event is triggered.
*Required*: No
*Type*: Integer
*Minimum*: `1`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`Location`
The fleet location.
*Required*: No
*Type*: String
*Pattern*: `^[A-Za-z0-9\-]+`
*Minimum*: `1`
*Maximum*: `64`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`MetricName`
Name of the Amazon GameLift Servers-defined metric that is used to trigger a scaling adjustment. For detailed descriptions of fleet metrics, see [Monitor Amazon GameLift Servers with Amazon CloudWatch](https://docs.amazonaws.cn/gamelift/latest/developerguide/monitoring-cloudwatch.html).
+ **ActivatingGameSessions** -- Game sessions in the process of being created.
+ **ActiveGameSessions** -- Game sessions that are currently running.
+ **ActiveInstances** -- Fleet instances that are currently running at least one game session.
+ **AvailableGameSessions** -- Additional game sessions that fleet could host simultaneously, given current capacity.
+ **AvailablePlayerSessions** -- Empty player slots in currently active game sessions. This includes game sessions that are not currently accepting players. Reserved player slots are not included.
+ **CurrentPlayerSessions** -- Player slots in active game sessions that are being used by a player or are reserved for a player.
+ **IdleInstances** -- Active instances that are currently hosting zero game sessions.
+ **PercentAvailableGameSessions** -- Unused percentage of the total number of game sessions that a fleet could host simultaneously, given current capacity. Use this metric for a target-based scaling policy.
+ **PercentIdleInstances** -- Percentage of the total number of active instances that are hosting zero game sessions.
+ **QueueDepth** -- Pending game session placement requests, in any queue, where the current fleet is the top-priority destination.
+ **WaitTime** -- Current wait time for pending game session placement requests, in any queue, where the current fleet is the top-priority destination.
*Required*: Yes
*Type*: String
*Allowed values*: `ActivatingGameSessions | ActiveGameSessions | ActiveInstances | AvailableGameSessions | AvailablePlayerSessions | CurrentPlayerSessions | IdleInstances | PercentAvailableGameSessions | PercentIdleInstances | QueueDepth | WaitTime | ConcurrentActivatableGameSessions`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`Name`
A descriptive label that is associated with a fleet's scaling policy. Policy names do not need to be unique.
*Required*: Yes
*Type*: String
*Minimum*: `1`
*Maximum*: `1024`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`PolicyType`
The type of scaling policy to create. For a target-based policy, set the parameter *MetricName* to 'PercentAvailableGameSessions' and specify a *TargetConfiguration*. For a rule-based policy set the following parameters: *MetricName*, *ComparisonOperator*, *Threshold*, *EvaluationPeriods*, *ScalingAdjustmentType*, and *ScalingAdjustment*.
*Required*: No
*Type*: String
*Allowed values*: `RuleBased | TargetBased`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`ScalingAdjustment`
Amount of adjustment to make, based on the scaling adjustment type.
*Required*: No
*Type*: Integer
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`ScalingAdjustmentType`
The type of adjustment to make to a fleet's instance count.
+ **ChangeInCapacity** -- add (or subtract) the scaling adjustment value from the current instance count. Positive values scale up while negative values scale down.
+ **ExactCapacity** -- set the instance count to the scaling adjustment value.
+ **PercentChangeInCapacity** -- increase or reduce the current instance count by the scaling adjustment, read as a percentage. Positive values scale up while negative values scale down.
*Required*: No
*Type*: String
*Allowed values*: `ChangeInCapacity | ExactCapacity | PercentChangeInCapacity`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`Status`
Current status of the scaling policy. The scaling policy can be in force only when in an `ACTIVE` status. Scaling policies can be suspended for individual fleets. If the policy is suspended for a fleet, the policy status does not change.
+ **ACTIVE** -- The scaling policy can be used for auto-scaling a fleet.
+ **UPDATE\_REQUESTED** -- A request to update the scaling policy has been received.
+ **UPDATING** -- A change is being made to the scaling policy.
+ **DELETE\_REQUESTED** -- A request to delete the scaling policy has been received.
+ **DELETING** -- The scaling policy is being deleted.
+ **DELETED** -- The scaling policy has been deleted.
+ **ERROR** -- An error occurred in creating the policy. It should be removed and recreated.
*Required*: No
*Type*: String
*Allowed values*: `ACTIVE | UPDATE_REQUESTED | UPDATING | DELETE_REQUESTED | DELETING | DELETED | ERROR`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`TargetConfiguration`
An object that contains settings for a target-based scaling policy.
*Required*: No
*Type*: [TargetConfiguration](aws-properties-gamelift-fleet-targetconfiguration.md)
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`Threshold`
Metric value used to trigger a scaling event.
*Required*: No
*Type*: Number
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)
`UpdateStatus`
The current status of the fleet's scaling policies in a requested fleet location. The status `PENDING_UPDATE` indicates that an update was requested for the fleet but has not yet been completed for the location.
*Required*: No
*Type*: String
*Allowed values*: `PENDING_UPDATE`
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)