autoscaling

name	autoscaling
description	Manage EC2 Auto Scaling groups, launch templates, scaling policies, and scheduled actions via AWS CLI.
metadata	{"openclaw":{"emoji":"📈","requires":{"bins":["aws"]}}}

EC2 Auto Scaling

Use this skill for auto scaling operations: managing Auto Scaling groups, launch templates, scaling policies, scheduled actions, instance refresh, and warm pools.

Prerequisites

• AWS CLI v2 configured with valid credentials
• IAM permissions: autoscaling:*, ec2:* (for launch templates)
• VPC subnets and security groups configured
• AMI or launch template for instances

Common Operations

List and Inspect (Read-Only)

# List Auto Scaling groups
aws autoscaling describe-auto-scaling-groups \
  --query 'AutoScalingGroups[*].[AutoScalingGroupName,MinSize,MaxSize,DesiredCapacity,length(Instances)]' --output table

# Describe a specific group
aws autoscaling describe-auto-scaling-groups \
  --auto-scaling-group-names <asg-name>

# List instances in a group
aws autoscaling describe-auto-scaling-instances \
  --query 'AutoScalingInstances[?AutoScalingGroupName==`<asg-name>`].[InstanceId,LifecycleState,HealthStatus,AvailabilityZone]' --output table

# List scaling activities
aws autoscaling describe-scaling-activities \
  --auto-scaling-group-name <asg-name> \
  --max-items 10 \
  --query 'Activities[*].[StartTime,StatusCode,Description]' --output table

# List scaling policies
aws autoscaling describe-policies \
  --auto-scaling-group-name <asg-name> \
  --query 'ScalingPolicies[*].[PolicyName,PolicyType,TargetTrackingConfiguration.TargetValue]' --output table

# List scheduled actions
aws autoscaling describe-scheduled-actions \
  --auto-scaling-group-name <asg-name> --output table

# List launch templates
aws ec2 describe-launch-templates \
  --query 'LaunchTemplates[*].[LaunchTemplateName,LaunchTemplateId,DefaultVersionNumber,LatestVersionNumber]' --output table

# Describe a launch template version
aws ec2 describe-launch-template-versions \
  --launch-template-name <template-name> \
  --versions '$Latest'

# List lifecycle hooks
aws autoscaling describe-lifecycle-hooks \
  --auto-scaling-group-name <asg-name> --output table

# Describe warm pool
aws autoscaling describe-warm-pool \
  --auto-scaling-group-name <asg-name>

# List notification configurations
aws autoscaling describe-notification-configurations \
  --auto-scaling-group-names <asg-name> --output table

Create and Configure

⚠️ Cost note: Auto Scaling itself is free. You pay for EC2 instances launched. Use spot instances with mixed instance policies to save 60-90%.

# Create a launch template
aws ec2 create-launch-template \
  --launch-template-name <template-name> \
  --launch-template-data '{
    "ImageId": "<ami-id>",
    "InstanceType": "t3.medium",
    "KeyName": "<key-pair>",
    "SecurityGroupIds": ["<sg-id>"],
    "UserData": "'$(echo -n '#!/bin/bash\nyum update -y' | base64)'"
  }'

# Create new launch template version
aws ec2 create-launch-template-version \
  --launch-template-name <template-name> \
  --source-version 1 \
  --launch-template-data '{"ImageId": "<new-ami-id>"}'

# Set default version
aws ec2 modify-launch-template \
  --launch-template-name <template-name> \
  --default-version <version-number>

# Create an Auto Scaling group
aws autoscaling create-auto-scaling-group \
  --auto-scaling-group-name <asg-name> \
  --launch-template LaunchTemplateName=<template-name>,Version='$Latest' \
  --min-size 1 \
  --max-size 5 \
  --desired-capacity 2 \
  --vpc-zone-identifier "<subnet-1>,<subnet-2>,<subnet-3>" \
  --target-group-arns <tg-arn> \
  --health-check-type ELB \
  --health-check-grace-period 300 \
  --tags Key=Name,Value=web-server,PropagateAtLaunch=true Key=Environment,Value=production,PropagateAtLaunch=true

# Create with mixed instances (spot + on-demand)
aws autoscaling create-auto-scaling-group \
  --auto-scaling-group-name <asg-name> \
  --mixed-instances-policy '{
    "LaunchTemplate": {
      "LaunchTemplateSpecification": {"LaunchTemplateName": "<template-name>", "Version": "$Latest"},
      "Overrides": [
        {"InstanceType": "t3.medium"},
        {"InstanceType": "t3a.medium"},
        {"InstanceType": "t3.large"}
      ]
    },
    "InstancesDistribution": {
      "OnDemandBaseCapacity": 1,
      "OnDemandPercentageAboveBaseCapacity": 25,
      "SpotAllocationStrategy": "capacity-optimized"
    }
  }' \
  --min-size 2 --max-size 10 --desired-capacity 4 \
  --vpc-zone-identifier "<subnet-1>,<subnet-2>"

Scaling Policies

# Target tracking policy (recommended)
aws autoscaling put-scaling-policy \
  --auto-scaling-group-name <asg-name> \
  --policy-name cpu-target-tracking \
  --policy-type TargetTrackingScaling \
  --target-tracking-configuration '{
    "PredefinedMetricSpecification": {"PredefinedMetricType": "ASGAverageCPUUtilization"},
    "TargetValue": 50.0
  }'

# Target tracking on ALB request count
aws autoscaling put-scaling-policy \
  --auto-scaling-group-name <asg-name> \
  --policy-name alb-request-tracking \
  --policy-type TargetTrackingScaling \
  --target-tracking-configuration '{
    "PredefinedMetricSpecification": {
      "PredefinedMetricType": "ALBRequestCountPerTarget",
      "ResourceLabel": "<alb-arn-suffix>/<tg-arn-suffix>"
    },
    "TargetValue": 1000.0
  }'

# Step scaling policy
aws autoscaling put-scaling-policy \
  --auto-scaling-group-name <asg-name> \
  --policy-name scale-out \
  --policy-type StepScaling \
  --adjustment-type ChangeInCapacity \
  --step-adjustments '[
    {"MetricIntervalLowerBound": 0, "MetricIntervalUpperBound": 20, "ScalingAdjustment": 1},
    {"MetricIntervalLowerBound": 20, "ScalingAdjustment": 2}
  ]'

# Scheduled action
aws autoscaling put-scheduled-update-group-action \
  --auto-scaling-group-name <asg-name> \
  --scheduled-action-name scale-up-morning \
  --recurrence "0 8 * * MON-FRI" \
  --min-size 4 --max-size 10 --desired-capacity 6

aws autoscaling put-scheduled-update-group-action \
  --auto-scaling-group-name <asg-name> \
  --scheduled-action-name scale-down-evening \
  --recurrence "0 20 * * MON-FRI" \
  --min-size 1 --max-size 5 --desired-capacity 2

# Predictive scaling
aws autoscaling put-scaling-policy \
  --auto-scaling-group-name <asg-name> \
  --policy-name predictive \
  --policy-type PredictiveScaling \
  --predictive-scaling-configuration '{
    "MetricSpecifications": [{
      "TargetValue": 50.0,
      "PredefinedMetricPairSpecification": {"PredefinedMetricType": "ASGCPUUtilization"}
    }],
    "Mode": "ForecastAndScale"
  }'

Instance Management

# Set desired capacity
aws autoscaling set-desired-capacity \
  --auto-scaling-group-name <asg-name> \
  --desired-capacity <count>

# Update min/max
aws autoscaling update-auto-scaling-group \
  --auto-scaling-group-name <asg-name> \
  --min-size <min> --max-size <max>

# Start an instance refresh (rolling update)
aws autoscaling start-instance-refresh \
  --auto-scaling-group-name <asg-name> \
  --preferences '{"MinHealthyPercentage": 90, "InstanceWarmup": 300}'

# Check instance refresh status
aws autoscaling describe-instance-refreshes \
  --auto-scaling-group-name <asg-name> \
  --query 'InstanceRefreshes[0].[Status,PercentageComplete,StatusReason]' --output table

# Cancel instance refresh
aws autoscaling cancel-instance-refresh --auto-scaling-group-name <asg-name>

# Detach instances (keep running outside ASG)
aws autoscaling detach-instances \
  --auto-scaling-group-name <asg-name> \
  --instance-ids <instance-id> \
  --should-decrement-desired-capacity

# Set instance protection
aws autoscaling set-instance-protection \
  --auto-scaling-group-name <asg-name> \
  --instance-ids <instance-id> \
  --protected-from-scale-in

Delete / Destructive

🛑 DESTRUCTIVE — Always confirm with the user before executing any of these commands.

# Delete an ASG (terminates all instances)
aws autoscaling delete-auto-scaling-group \
  --auto-scaling-group-name <asg-name> \
  --force-delete

# Delete without force (must set desired to 0 and wait first)
aws autoscaling update-auto-scaling-group \
  --auto-scaling-group-name <asg-name> \
  --min-size 0 --desired-capacity 0
# Wait for instances to terminate, then:
aws autoscaling delete-auto-scaling-group --auto-scaling-group-name <asg-name>

# Delete a scaling policy
aws autoscaling delete-policy \
  --auto-scaling-group-name <asg-name> \
  --policy-name <policy-name>

# Delete a launch template
aws ec2 delete-launch-template --launch-template-name <template-name>

Safety Rules

1. NEVER force-delete an ASG without explicit user confirmation — terminates all instances.
2. NEVER expose or log AWS credentials or user data secrets.
3. ALWAYS confirm the ASG name and desired capacity before changes.
4. ALWAYS use instance refresh for rolling updates instead of manual replacement.
5. WARN about setting desired capacity to 0 — terminates all instances.
6. WARN about cost of scaling out, especially with large instance types.

Best Practices

• Use target tracking scaling as the primary policy (simpler, more responsive).
• Use mixed instance policies with spot for cost savings.
• Set health check type to ELB when using a load balancer.
• Use instance refresh for AMI updates instead of manual replacement.
• Set appropriate health check grace period for application startup time.

Common Patterns

Pattern: Rolling AMI Update

# Create new launch template version with new AMI
aws ec2 create-launch-template-version \
  --launch-template-name <template-name> \
  --source-version '$Latest' \
  --launch-template-data '{"ImageId": "<new-ami-id>"}'

# Start instance refresh
aws autoscaling start-instance-refresh \
  --auto-scaling-group-name <asg-name> \
  --preferences '{"MinHealthyPercentage": 90, "InstanceWarmup": 300}'

# Monitor progress
aws autoscaling describe-instance-refreshes \
  --auto-scaling-group-name <asg-name> \
  --query 'InstanceRefreshes[0].[Status,PercentageComplete]' --output table

Troubleshooting

Error	Cause	Fix
Instances not launching	Launch template or AMI issue	Check scaling activities for error details
ValidationError	Invalid parameter combination	Verify subnet IDs, SG IDs, and launch template
Instances stuck in Pending	Insufficient capacity in AZ	Add more AZs or use mixed instance types
Health check failures	App not ready within grace period	Increase health-check-grace-period
Instance refresh stuck	Instances failing health checks	Check app health; cancel refresh if needed
Scale-in too aggressive	Cooldown too short	Increase cooldown or use scale-in protection