Amazon Auto Scaling Essentials

# Create AMI from existing instance
aws ec2 create-image \
    --instance-id i-1234567890abcdef0 \
    --name "myapp-v1.0.0" \
    --description "Production app with dependencies" \
    --no-reboot  # Avoids downtime

# Create Launch Template
aws ec2 create-launch-template \
    --launch-template-name myapp-template \
    --version-description "Initial version" \
    --launch-template-data '{
        "ImageId": "ami-0abc123",
        "InstanceType": "t3.micro",
        "SecurityGroupIds": ["sg-12345"],
        "UserData": "IyEvYmluL2Jhc2g...",
        "IamInstanceProfile": {"Name": "ec2-role"},
        "KeyName": "my-keypair"
    }'

# Create new version of Launch Template
aws ec2 create-launch-template-version \
    --launch-template-id lt-0abc123 \
    --version-description "Updated to t3.small" \
    --launch-template-data '{"InstanceType": "t3.small"}'

# Create Target Group
aws elbv2 create-target-group \
    --name myapp-targets \
    --protocol HTTP \
    --port 80 \
    --vpc-id vpc-12345 \
    --health-check-path /health \
    --health-check-interval-seconds 30 \
    --healthy-threshold-count 2 \
    --unhealthy-threshold-count 3

# Create Application Load Balancer
aws elbv2 create-load-balancer \
    --name myapp-lb \
    --subnets subnet-abc123 subnet-def456 \
    --security-groups sg-12345 \
    --scheme internet-facing \
    --type application

# Create Listener (connects LB with Target Group)
aws elbv2 create-listener \
    --load-balancer-arn arn:aws:elasticloadbalancing:... \
    --protocol HTTP \
    --port 80 \
    --default-actions Type=forward,TargetGroupArn=arn:aws:...

# Create Auto-Scaling Group
aws autoscaling create-auto-scaling-group \
    --auto-scaling-group-name myapp-asg \
    --launch-template LaunchTemplateId=lt-0abc123,Version='$Latest' \
    --min-size 2 \
    --max-size 10 \
    --desired-capacity 2 \
    --target-group-arns arn:aws:elasticloadbalancing:... \
    --vpc-zone-identifier "subnet-abc,subnet-def" \
    --health-check-type ELB \
    --health-check-grace-period 300

# Create Target Tracking Scaling Policy
aws autoscaling put-scaling-policy \
    --auto-scaling-group-name myapp-asg \
    --policy-name target-tracking-cpu \
    --policy-type TargetTrackingScaling \
    --target-tracking-configuration '{
        "PredefinedMetricSpecification": {
            "PredefinedMetricType": "ASGAverageCPUUtilization"
        },
        "TargetValue": 70.0
    }'

# View your own AMIs
aws ec2 describe-images --owners self

# View Launch Templates
aws ec2 describe-launch-templates
aws ec2 describe-launch-template-versions --launch-template-id lt-0abc123

# View Auto-Scaling Groups
aws autoscaling describe-auto-scaling-groups \
    --auto-scaling-group-names myapp-asg

# View instances in the ASG
aws autoscaling describe-auto-scaling-groups \
    --auto-scaling-group-names myapp-asg \
    --query 'AutoScalingGroups[0].Instances[*].[InstanceId,LifecycleState,HealthStatus,AvailabilityZone]' \
    --output table

# View ASG activities (troubleshooting)
aws autoscaling describe-scaling-activities \
    --auto-scaling-group-name myapp-asg \
    --max-records 10

# View target health
aws elbv2 describe-target-health \
    --target-group-arn arn:aws:elasticloadbalancing:...

# View Load Balancers
aws elbv2 describe-load-balancers

# Update ASG (change capacity)
aws autoscaling update-auto-scaling-group \
    --auto-scaling-group-name myapp-asg \
    --min-size 3 \
    --max-size 15 \
    --desired-capacity 5

# Update ASG (change Launch Template)
aws autoscaling update-auto-scaling-group \
    --auto-scaling-group-name myapp-asg \
    --launch-template LaunchTemplateId=lt-0abc123,Version='$Latest'

# Manually change desired capacity
aws autoscaling set-desired-capacity \
    --auto-scaling-group-name myapp-asg \
    --desired-capacity 8

# Delete Auto-Scaling Group (terminates instances)
aws autoscaling delete-auto-scaling-group \
    --auto-scaling-group-name myapp-asg \
    --force-delete

# Delete Load Balancer
aws elbv2 delete-load-balancer \
    --load-balancer-arn arn:aws:elasticloadbalancing:...

# Delete Target Group
aws elbv2 delete-target-group \
    --target-group-arn arn:aws:elasticloadbalancing:...

# Delete Launch Template
aws ec2 delete-launch-template \
    --launch-template-id lt-0abc123

# Deregister AMI
aws ec2 deregister-image --image-id ami-0abc123

# Target Tracking instead of keeping idle instances
# Scales only when needed
--target-tracking-configuration TargetValue=70.0

# Reduce to minimum outside business hours
aws autoscaling put-scheduled-update-group-action \
    --auto-scaling-group-name myapp-asg \
    --scheduled-action-name scale-down-night \
    --recurrence "0 22 * * *" \
    --min-size 1 --desired-capacity 1