Use DetachInstances with a CLI

To detach an instance from an Auto Scaling group

This example detaches the specified instance from the specified Auto Scaling group.

aws autoscaling detach-instances \
    --instance-ids i-030017cfa84b20135 \
    --auto-scaling-group-name my-asg \
    --should-decrement-desired-capacity

Output:

{
    "Activities": [
        {
            "ActivityId": "5091cb52-547a-47ce-a236-c9ccbc2cb2c9",
            "AutoScalingGroupName": "my-asg",
            "Description": "Detaching EC2 instance: i-030017cfa84b20135",
            "Cause": "At 2020-10-31T17:35:04Z instance i-030017cfa84b20135 was detached in response to a user request, shrinking the capacity from 2 to 1.",
            "StartTime": "2020-04-12T15:02:16.179Z",
            "StatusCode": "InProgress",
            "Progress": 50,
            "Details": "{\"Subnet ID\":\"subnet-6194ea3b\",\"Availability Zone\":\"us-west-2c\"}"
        }
    ]
}

Example 1: This example detaches the specified instance from the specified Auto Scaling group and decreases the desired capacity so that Auto Scaling does not launch a replacement instance.

Dismount-ASInstance -InstanceId i-93633f9b -AutoScalingGroupName my-asg -ShouldDecrementDesiredCapacity $true

Output:

ActivityId           : 06733445-ce94-4039-be1b-b9f1866e276e
AutoScalingGroupName : my-asg
Cause                : At 2015-11-20T22:34:59Z instance i-93633f9b was detached in response to a user request, shrinking
                       the capacity from 2 to 1.
Description          : Detaching EC2 instance: i-93633f9b
Details              : {"Availability Zone":"us-west-2b","Subnet ID":"subnet-5264e837"}
EndTime              : 
Progress             : 50
StartTime            : 11/20/2015 2:34:59 PM
StatusCode           : InProgress
StatusMessage        :

Example 2: This example detaches the specified instance from the specified Auto Scaling group without decreasing the desired capacity. Auto Scaling launches a replacement instance.

Dismount-ASInstance -InstanceId i-7bf746a2 -AutoScalingGroupName my-asg -ShouldDecrementDesiredCapacity $false

Output:

ActivityId           : f43a3cd4-d38c-4af7-9fe0-d76ec2307b6d
AutoScalingGroupName : my-asg
Cause                : At 2015-11-20T22:34:59Z instance i-7bf746a2 was detached in response to a user request.
Description          : Detaching EC2 instance: i-7bf746a2
Details              : {"Availability Zone":"us-west-2b","Subnet ID":"subnet-5264e837"}
EndTime              : 
Progress             : 50
StartTime            : 11/20/2015 2:34:59 PM
StatusCode           : InProgress
StatusMessage        :

Example 1: This example detaches the specified instance from the specified Auto Scaling group and decreases the desired capacity so that Auto Scaling does not launch a replacement instance.

Dismount-ASInstance -InstanceId i-93633f9b -AutoScalingGroupName my-asg -ShouldDecrementDesiredCapacity $true

Output:

ActivityId           : 06733445-ce94-4039-be1b-b9f1866e276e
AutoScalingGroupName : my-asg
Cause                : At 2015-11-20T22:34:59Z instance i-93633f9b was detached in response to a user request, shrinking
                       the capacity from 2 to 1.
Description          : Detaching EC2 instance: i-93633f9b
Details              : {"Availability Zone":"us-west-2b","Subnet ID":"subnet-5264e837"}
EndTime              : 
Progress             : 50
StartTime            : 11/20/2015 2:34:59 PM
StatusCode           : InProgress
StatusMessage        :

Example 2: This example detaches the specified instance from the specified Auto Scaling group without decreasing the desired capacity. Auto Scaling launches a replacement instance.

Dismount-ASInstance -InstanceId i-7bf746a2 -AutoScalingGroupName my-asg -ShouldDecrementDesiredCapacity $false

Output:

ActivityId           : f43a3cd4-d38c-4af7-9fe0-d76ec2307b6d
AutoScalingGroupName : my-asg
Cause                : At 2015-11-20T22:34:59Z instance i-7bf746a2 was detached in response to a user request.
Description          : Detaching EC2 instance: i-7bf746a2
Details              : {"Availability Zone":"us-west-2b","Subnet ID":"subnet-5264e837"}
EndTime              : 
Progress             : 50
StartTime            : 11/20/2015 2:34:59 PM
StatusCode           : InProgress
StatusMessage        :