A Fleet represents a managed set of EC2 instances.

The Fleet models a number of AutoScalingGroups, a launch configuration, a
security group and an instance role.

It allows adding arbitrary commands to the startup scripts of the instances
in the fleet.

The ASG spans the availability zones specified by vpcSubnets, falling back to
the Vpc default strategy if not specified.

Send a message to either an SQS queue or SNS topic when instances launch or terminate.

addLifecycleHook

Add the security group to all instances via the launch template security groups array.

addSecurityGroup

Adds a statement to the IAM role assumed by instances of this fleet.

addToRolePolicy

Add command to the startup script of fleet instances.

The command must be in the scripting language supported by the fleet's OS (i.e. Linux/Windows).
Does nothing for imported ASGs.

addUserData

Add a pool of pre-initialized EC2 instances that sits alongside an Auto Scaling group.

addWarmPool

Use a CloudFormation Init configuration at instance startup.

This does the following:

- Attaches the CloudFormation Init metadata to the AutoScalingGroup resource.
- Add commands to the UserData to run `cfn-init` and `cfn-signal`.
- Update the instance's CreationPolicy to wait for `cfn-init` to finish
  before reporting success.

applyCloudFormationInit

Returns `true` if newly-launched instances are protected from scale-in.

areNewInstancesProtectedFromScaleIn

Attach to ELBv2 Application Target Group.

attachToApplicationTargetGroup

attachToClassicLB

attachToNetworkTargetGroup

Ensures newly-launched instances are protected from scale-in.

protectNewInstancesFromScaleIn

Scale out or in to achieve a target CPU utilization.

scaleOnCpuUtilization

Scale out or in to achieve a target network ingress rate.

scaleOnIncomingBytes

Scale out or in, in response to a metric.

scaleOnMetric

Scale out or in to achieve a target network egress rate.

scaleOnOutgoingBytes

Scale out or in to achieve a target request handling rate.

The AutoScalingGroup must have been attached to an Application Load Balancer
in order to be able to call this.

scaleOnRequestCount

scaleOnSchedule

Scale out or in in order to keep a metric around a target value.

scaleToTrackMetric

AutoScalingGroup

Apply the given CloudFormation Init configuration to the instances in the AutoScalingGroup at startup.

If you specify `init`, you must also specify `signals` to configure
the number of instances to wait for and the timeout for waiting for the
init process.

init

Use the given options for applying CloudFormation Init.

Describes the configsets to use and the timeout to wait

initOptions

Type of instance to launch.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

instanceType

Launch template to use.

Launch configuration related settings and MixedInstancesPolicy must not be specified when a
launch template is specified.

launchTemplate

AMI to launch.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

machineImage

Specifies the upper threshold as a percentage of the desired capacity of the Auto Scaling group.

It represents the maximum percentage of the group that can be in service and healthy, or pending,
to support your workload when replacing instances.

Value range is 0 to 100. After it's set, both `minHealthyPercentage` and `maxHealthyPercentage` to
-1 will clear the previously set value.

Both or neither of `minHealthyPercentage` and `maxHealthyPercentage` must be specified, and the
difference between them cannot be greater than 100. A large range increases the number of
instances that can be replaced at the same time.

maxHealthyPercentage

Whether safety guardrail should be enforced when migrating to the launch template.

migrateToLaunchTemplate

Specifies the lower threshold as a percentage of the desired capacity of the Auto Scaling group.

It represents the minimum percentage of the group to keep in service, healthy, and ready to use
to support your workload when replacing instances.

Value range is 0 to 100. After it's set, both `minHealthyPercentage` and `maxHealthyPercentage` to
-1 will clear the previously set value.

Both or neither of `minHealthyPercentage` and `maxHealthyPercentage` must be specified, and the
difference between them cannot be greater than 100. A large range increases the number of
instances that can be replaced at the same time.

minHealthyPercentage

Mixed Instances Policy to use.

Launch configuration related settings and Launch Template  must not be specified when a
MixedInstancesPolicy is specified.

mixedInstancesPolicy

Whether IMDSv2 should be required on launched instances.

requireImdsv2

An IAM role to associate with the instance profile assigned to this Auto Scaling Group.

The role must be assumable by the service principal `ec2.amazonaws.com`:

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

role

Security group to launch the instances in.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

securityGroup

Specific UserData to use.

The UserData may still be mutated after creation.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

userData

Whether the instances can initiate connections to anywhere by default.

allowAllOutbound

Whether instances in the Auto Scaling Group should have public IP addresses associated with them.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

associatePublicIpAddress

The name of the Auto Scaling group.

This name must be unique per Region per account.

autoScalingGroupName

The strategy for distributing instances across Availability Zones.

azCapacityDistributionStrategy

Specifies how block devices are exposed to the instance. You can specify virtual devices and EBS volumes.

Each instance that is launched has an associated root device volume,
either an Amazon EBS volume or an instance store volume.
You can use block device mappings to specify additional EBS volumes or
instance store volumes to attach to an instance when it is launched.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

blockDevices

Indicates whether Capacity Rebalancing is enabled.

When you turn on Capacity Rebalancing, Amazon EC2 Auto Scaling
attempts to launch a Spot Instance whenever Amazon EC2 notifies that a Spot Instance is at an elevated risk of
interruption. After launching a new instance, it then terminates an old instance.

capacityRebalance

Default scaling cooldown for this AutoScalingGroup.

cooldown

The amount of time, in seconds, until a newly launched instance can contribute to the Amazon CloudWatch metrics.

This delay lets an instance finish initializing before Amazon EC2 Auto Scaling aggregates instance metrics,
resulting in more reliable usage data. Set this value equal to the amount of time that it takes for resource
consumption to become stable after an instance reaches the InService state.

To optimize the performance of scaling policies that scale continuously, such as target tracking and
step scaling policies, we strongly recommend that you enable the default instance warmup, even if its value is set to 0 seconds

Default instance warmup will not be added if no value is specified

defaultInstanceWarmup

Deletion protection for the Auto Scaling group.

deletionProtection

Initial amount of instances in the fleet.

If this is set to a number, every deployment will reset the amount of
instances to this number. It is recommended to leave this value blank.

desiredCapacity

Enable monitoring for group metrics, these metrics describe the group rather than any of its instances.

To report all group metrics use `GroupMetrics.all()`
Group metrics are reported in a granularity of 1 minute at no additional charge.

groupMetrics

healthCheck

Configuration for EC2 or additional health checks.

Even when using `HealthChecks.withAdditionalChecks()`, the EC2 type is implicitly included.

healthChecks

If the ASG has scheduled actions, don't reset unchanged group sizes.

Only used if the ASG has scheduled actions (which may scale your ASG up
or down regardless of cdk deployments). If true, the size of the group
will only be reset if it has been changed in the CDK app. If false, the
sizes will always be changed back to what they were in the CDK app
on deployment.

ignoreUnmodifiedSizeProperties

An instance lifecycle policy that defines how instances should be handled during lifecycle events, particularly when lifecycle hooks are abandoned or fail.

instanceLifecyclePolicy

Controls whether instances in this group are launched with detailed or basic monitoring.

When detailed monitoring is enabled, Amazon CloudWatch generates metrics every minute and your account
is charged a fee. When you disable detailed monitoring, CloudWatch generates metrics every 5 minutes.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

instanceMonitoring

Name of SSH keypair to grant access to instances.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

You can either specify `keyPair` or `keyName`, not both.

keyName

The SSH keypair to grant access to the instance.

Feature flag `AUTOSCALING_GENERATE_LAUNCH_TEMPLATE` must be enabled to use this property.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified.

You can either specify `keyPair` or `keyName`, not both.

keyPair

Maximum number of instances in the fleet.

maxCapacity

The maximum amount of time that an instance can be in service.

The maximum duration applies
to all current and future instances in the group. As an instance approaches its maximum duration,
it is terminated and replaced, and cannot be used again.

You must specify a value of at least 86,400 seconds (one day). To clear a previously set value,
leave this property undefined.

maxInstanceLifetime

Minimum number of instances in the fleet.

minCapacity

Whether newly-launched instances are protected from termination by Amazon EC2 Auto Scaling when scaling in.

By default, Auto Scaling can terminate an instance at any time after launch
when scaling in an Auto Scaling Group, subject to the group's termination
policy. However, you may wish to protect newly-launched instances from
being scaled in if they are going to run critical applications that should
not be prematurely terminated.

This flag must be enabled if the Auto Scaling Group will be associated with
an ECS Capacity Provider with managed termination protection.

newInstancesProtectedFromScaleIn

Configure autoscaling group to send notifications about fleet changes to an SNS topic(s).

notifications

Configure waiting for signals during deployment.

Use this to pause the CloudFormation deployment to wait for the instances
in the AutoScalingGroup to report successful startup during
creation and updates. The UserData script needs to invoke `cfn-signal`
with a success or failure code after it is done setting up the instance.

Without waiting for signals, the CloudFormation deployment will proceed as
soon as the AutoScalingGroup has been created or updated but before the
instances in the group have been started.

For example, to have instances wait for an Elastic Load Balancing health check before
they signal success, add a health-check verification by using the
cfn-init helper script. For an example, see the verify_instance_health
command in the Auto Scaling rolling updates sample template:

https://github.com/awslabs/aws-cloudformation-templates/blob/master/aws/services/AutoScaling/AutoScalingRollingUpdates.yaml

signals

The maximum hourly price (in USD) to be paid for any Spot Instance launched to fulfill the request.

Spot Instances are
launched when the price you specify exceeds the current Spot market price.

`launchTemplate` and `mixedInstancesPolicy` must not be specified when this property is specified

spotPrice

Add SSM session permissions to the instance role.

Setting this to `true` adds the necessary permissions to connect
to the instance using SSM Session Manager. You can do this
from the AWS Console.

NOTE: Setting this flag to `true` may not be enough by itself.
You must also use an AMI that comes with the SSM Agent, or install
the SSM Agent yourself. See
[Working with SSM Agent](https://docs.aws.amazon.com/systems-manager/latest/userguide/ssm-agent.html)
in the SSM Developer Guide.

ssmSessionPermissions

A policy or a list of policies that are used to select the instances to terminate.

The policies are executed in the order that you list them.

terminationPolicies

A lambda function Arn that can be used as a custom termination policy to select the instances to terminate.

This property must be specified if the TerminationPolicy.CUSTOM_LAMBDA_FUNCTION
is used.

terminationPolicyCustomLambdaFunctionArn

What to do when an AutoScalingGroup's instance configuration is changed.

This is applied when any of the settings on the ASG are changed that
affect how the instances should be created (VPC, instance type, startup
scripts, etc.). It indicates how the existing instances should be
replaced with new instances matching the new config. By default, nothing
is done and only new instances are launched with the new config.

updatePolicy

vpcSubnets

LifecycleHook

The AutoScalingGroup to add the lifecycle hook to.

autoScalingGroup

The state of the Amazon EC2 instance to which you want to attach the lifecycle hook.

lifecycleTransition

The action the Auto Scaling group takes when the lifecycle hook timeout elapses or if an unexpected failure occurs.

defaultResult

Maximum time between calls to RecordLifecycleActionHeartbeat for the hook.

If the lifecycle hook times out, perform the action in DefaultResult.

heartbeatTimeout

lifecycleHookName

Additional data to pass to the lifecycle hook target.

notificationMetadata

notificationTarget

The role that allows publishing to the notification target.

ScheduledAction

The AutoScalingGroup to apply the scheduled actions to.

When to perform this action.

Supports cron expressions.

For more information about cron expressions, see https://en.wikipedia.org/wiki/Cron.

schedule

The new desired capacity.

At the scheduled time, set the desired capacity to the given capacity.

At least one of maxCapacity, minCapacity, or desiredCapacity must be supplied.

endTime

The new maximum capacity.

At the scheduled time, set the maximum capacity to the given capacity.

At least one of maxCapacity, minCapacity, or desiredCapacity must be supplied.

The new minimum capacity.

At the scheduled time, set the minimum capacity to the given capacity.

At least one of maxCapacity, minCapacity, or desiredCapacity must be supplied.

When this scheduled action becomes active.

startTime

Specifies the time zone for a cron expression.

If a time zone is not provided, UTC is used by default.

Valid values are the canonical names of the IANA time zones, derived from the IANA Time Zone Database (such as Etc/GMT+9 or Pacific/Tahiti).

For more information, see https://en.wikipedia.org/wiki/List_of_tz_database_time_zones.

timeZone

Define a step scaling action.

This kind of scaling policy adjusts the target capacity in configurable
steps. The size of the step is configurable based on the metric's distance
to its alarm threshold.

This Action must be used as the target of a CloudWatch alarm to take effect.

Add an adjustment interval to the ScalingAction.

addAdjustment

StepScalingAction

How the adjustment numbers are interpreted.

adjustmentType

Period after a scaling completes before another scaling activity can start.

Estimated time until a newly launched instance can send metrics to CloudWatch.

estimatedInstanceWarmup

The aggregation type for the CloudWatch metrics.

metricAggregationType

Minimum absolute number to adjust capacity with as result of percentage scaling.

Only when using AdjustmentType = PercentChangeInCapacity, this number controls
the minimum absolute effect size.

minAdjustmentMagnitude

Define a acaling strategy which scales depending on absolute values of some metric.

You can specify the scaling behavior for various values of the metric.

Implemented using one or more CloudWatch alarms and Step Scaling Policies.

StepScalingPolicy

metric

The intervals for scaling.

Maps a range of metric values to a particular scaling behavior.

Must be between 2 and 40 steps.

scalingSteps

How the adjustment numbers inside 'intervals' are interpreted.

The number of data points out of the evaluation periods that must be breaching to trigger a scaling action.

Creates an "M out of N" alarm, where this property is the M and the value set for
`evaluationPeriods` is the N value.

Only has meaning if `evaluationPeriods != 1`. Must be less than or equal to
`evaluationPeriods`.

datapointsToAlarm

How many evaluation periods of the metric to wait before triggering a scaling action.

Raising this value can be used to smooth out the metric, at the expense
of slower response times.

If `datapointsToAlarm` is not set, then all data points in the evaluation period
must meet the criteria to trigger a scaling action.

evaluationPeriods

Aggregation to apply to all data points over the evaluation periods.

Only has meaning if `evaluationPeriods != 1`.

TargetTrackingScalingPolicy

targetValue

A custom metric for application autoscaling.

The metric must track utilization. Scaling out will happen if the metric is higher than
the target value, scaling in will happen in the metric is lower than the target value.

Exactly one of customMetric or predefinedMetric must be specified.

customMetric

A predefined metric for application autoscaling.

The metric must track utilization. Scaling out will happen if the metric is higher than
the target value, scaling in will happen in the metric is lower than the target value.

Exactly one of customMetric or predefinedMetric must be specified.

predefinedMetric

The resource label associated with the predefined metric.

Should be supplied if the predefined metric is ALBRequestCountPerTarget, and the
format should be:

app/<load-balancer-name>/<load-balancer-id>/targetgroup/<target-group-name>/<target-group-id>

resourceLabel

Indicates whether scale in by the target tracking policy is disabled.

If the value is true, scale in is disabled and the target tracking policy
won't remove capacity from the autoscaling group. Otherwise, scale in is
enabled and the target tracking policy can remove capacity from the
group.

disableScaleIn

WarmPool

The Auto Scaling group to add the warm pool to.

The maximum number of instances that are allowed to be in the warm pool or in any state except Terminated for the Auto Scaling group.

If the value is not specified, Amazon EC2 Auto Scaling launches and maintains
the difference between the group's maximum capacity and its desired capacity.

maxGroupPreparedCapacity

The minimum number of instances to maintain in the warm pool.

minSize

The instance state to transition to after the lifecycle actions are complete.

poolState

Indicates whether instances in the Auto Scaling group can be returned to the warm pool on scale in.

If the value is not specified, instances in the Auto Scaling group will be terminated
when the group scales in.

reuseOnScaleIn

The `AWS::AutoScaling::AutoScalingGroup` resource defines an Amazon EC2 Auto Scaling group, which is a collection of Amazon EC2 instances that are treated as a logical grouping for the purposes of automatic scaling and management.

For more information about Amazon EC2 Auto Scaling, see the [Amazon EC2 Auto Scaling User Guide](https://docs.aws.amazon.com/autoscaling/ec2/userguide/what-is-amazon-ec2-auto-scaling.html) .

> Amazon EC2 Auto Scaling configures instances launched as part of an Auto Scaling group using either a [launch template](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-launchtemplate.html) or a launch configuration. We strongly recommend that you do not use launch configurations. For more information, see [Launch configurations](https://docs.aws.amazon.com/autoscaling/ec2/userguide/launch-configurations.html) in the *Amazon EC2 Auto Scaling User Guide* .
>
> For help migrating from launch configurations to launch templates, see [Migrate AWS CloudFormation stacks from launch configurations to launch templates](https://docs.aws.amazon.com/autoscaling/ec2/userguide/migrate-launch-configurations-with-cloudformation.html) in the *Amazon EC2 Auto Scaling User Guide* .

CfnAutoScalingGroup

The maximum size of the group.

> With a mixed instances policy that uses instance weighting, Amazon EC2 Auto Scaling may need to go above `MaxSize` to meet your capacity requirements. In this event, Amazon EC2 Auto Scaling will never go above `MaxSize` by more than your largest instance weight (weights that define how many units each instance contributes to the desired capacity of the group).

maxSize

The name of the Auto Scaling group. This name must be unique per Region per account.

The name can contain any ASCII character 33 to 126 including most punctuation characters, digits, and upper and lowercased letters.

> You cannot use a colon (:) in the name.

The EC2 instance capacity distribution across Availability Zones for the Auto Scaling group.

availabilityZoneDistribution

availabilityZoneIds

The Availability Zone impairment policy for the Auto Scaling group.

availabilityZoneImpairmentPolicy

A list of Availability Zones where instances in the Auto Scaling group can be created.

Used for launching into the default VPC subnet in each Availability Zone when not using the `VPCZoneIdentifier` property, or for attaching a network interface when an existing network interface ID is specified in a launch template.

AWS Auto Scaling

L2 Constructs7

AutoScalingGroup

LifecycleHook

ScheduledAction

StepScalingAction

StepScalingPolicy

TargetTrackingScalingPolicy

WarmPool

L1 Constructs6

CfnAutoScalingGroup

CfnLaunchConfiguration

CfnLifecycleHook

CfnScalingPolicy

CfnScheduledAction

CfnWarmPool

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