• Setup autoscaling and cloudwatch CLI
  

  cd /home/john && mkdir ec2 && cd ec2
   
  wget http://ec2-downloads.s3.amazonaws.com/AutoScaling-2011-01-01.zip
  unzip AutoScaling-2011-01-01.zip
  wget http://ec2-downloads.s3.amazonaws.com/CloudWatch-2010-08-01.zip
  unzip CloudWatch-2010-08-01.zip
   
  export EC2_HOME=/home/john/ec2
  export PATH=$PATH:$EC2_HOME/bin  
  export JAVA_HOME=/usr
  export EC2_PRIVATE_KEY=/home/john/pk.pem # You need to get this file from your AWS Credentials
  export EC2_CERT=/home/john/cert.pem      # You need to get this file from your AWS Credentials
   
  export AWS_AUTO_SCALING_HOME=$EC2_HOME/AutoScaling-1.0.49.1
  export AWS_AUTO_SCALING_URL=https://autoscaling.us-east-1.amazonaws.com
  export PATH=$PATH:$AWS_AUTO_SCALING_HOME/bin
   
  export AWS_CLOUDWATCH_HOME=$EC2_HOME/CloudWatch-1.0.12.1
  export PATH=$PATH:$AWS_CLOUDWATCH_HOME/bin

• Setup variables
  

  EC2_REGION="us-east-1"
  ZONE="us-east-1d"
  SECURITY_GROUP="default"
  INSTANCE_SIZE="t1.micro"
  LB_NAME="autoscalelb"
  LC_NAME="autoscalelc"
  LC_IMAGE_ID="ami-31814f58" # Could be any AMI of choice
  LC_KEY="john-east"  # You need to create this key in the AWS console
  SG_NAME="autoscalesg"
   
  UP_POLICY_NAME="MyScaleUpPolicy"
  DOWN_POLICY_NAME="MyScaleDownPolicy"
  HIGH_CPU_ALRM_NAME="MyHighCPUAlarm"
  LOW_CPU_ALRM_NAME="MyLowCPUAlarm"
  MIN_SIZE=1
  MAX_SIZE=4  # For testing purposes, set to 1
  DOWN_THRESHOLD=40  # scale down when average CPU load is 40% or below 
  UP_THRESHOLD=80  # scale up when average CPU load reaches 80%

• Create Launch Config
  

  as-create-launch-config $LC_NAME --image-id $LC_IMAGE_ID --instance-type $INSTANCE_SIZE --group $SECURITY_GROUP --key $LC_KEY --block-device-mapping '/dev/sda2=ephemeral0' --user-data-file ud.txt

• Create Autoscaling Group
  

  as-create-auto-scaling-group $SG_NAME --availability-zones $ZONE --launch-configuration $LC_NAME --min-size $MIN_SIZE --max-size $MAX_SIZE --load-balancers $LB_NAME

• Trigger scaling up
  

  ARN_HIGH=`as-put-scaling-policy $UP_POLICY_NAME --auto-scaling-group $SG_NAME --adjustment=1 --type ChangeInCapacity --cooldown 300`
  mon-put-metric-alarm $HIGH_CPU_ALRM_NAME --comparison-operator GreaterThanThreshold --evaluation-periods 1 --metric-name CPUUtilization --namespace "AWS/EC2" --period 600 --statistic Average --threshold $UP_THRESHOLD --alarm-actions $ARN_HIGH --dimensions "AutoScalingGroupName=$SG_NAME"

• Trigger scaling down
  

  ARN_LOW=`as-put-scaling-policy $DOWN_POLICY_NAME --auto-scaling-group $SG_NAME --adjustment=-1 --type ChangeInCapacity --cooldown 300`
  mon-put-metric-alarm $LOW_CPU_ALRM_NAME --comparison-operator LessThanThreshold --evaluation-periods 1 --metric-name CPUUtilization --namespace "AWS/EC2" --period 600 --statistic Average --threshold $DOWN_THRESHOLD --alarm-actions $ARN_LOW --dimensions "AutoScalingGroupName=$SG_NAME"
  
  #Post notifications to SNS (needed for dynamic registration)
  as-put-notification-configuration $SG_NAME --topic-arn arn:aws:sns:us-east-1:123456789012:topic01 --notification-types autoscaling:EC2_INSTANCE_LAUNCH, autoscaling:EC2_INSTANCE_TERMINATE
  

• Pausing and Restarting autoscaling activities
  

  as-suspend-processes $SG_NAME
  as-resume-processes $SG_NAME

• Expand to other Availability Zones
  

  as-update-auto-scaling-group $SG_NAME --availability-zones us-east-1a, us-east-1b, us-east-1c --min-size 3
  elb-describe-instance-health  $LB_NAME
  elb-enable-zones-for-lb  $LB_NAME  --headers --availability-zones us-east-1c 

• Clean up
  

  as-update-auto-scaling-group $SG_NAME --min-size 0 --max-size 0
  as-delete-auto-scaling-group $SG_NAME
  as-delete-launch-config $LC_NAME
   
  mon-delete-alarms $HIGH_CPU_ALRM_NAME $LOW_CPU_ALRM_NAME

References