{"id":36155,"date":"2016-06-23T16:05:54","date_gmt":"2016-06-23T10:35:54","guid":{"rendered":"https:\/\/2thenew.today\/blog\/?p=36155"},"modified":"2016-12-19T15:02:54","modified_gmt":"2016-12-19T09:32:54","slug":"aws-autoscaling-group-configured-with-elb-and-alarms-in-boto-python","status":"publish","type":"post","link":"https:\/\/2thenew.today\/blog\/aws-autoscaling-group-configured-with-elb-and-alarms-in-boto-python\/","title":{"rendered":"AWS Autoscaling group configured with ELB and Alarms in Boto (Python)"},"content":{"rendered":"

\"boto\"<\/p>\n

Autoscaling is a service<\/a>\u00a0in AWS, which is used to launch or terminate an instance based on user-defined policies, health checks, and schedules.<\/p>\n

There are several ways to configure an auto-scaling group in AWS, here we are focusing on implementing it in python using AWS python module boto.<\/p>\n

Before Creating \u00a0an Autoscaling Group\u00a0 we have to keep in mind the following steps:<\/p>\n

    \n
  1. Autoscaling Group<\/strong>: It is a group used for maintaining or scaling a set of EC2 instances in one or more availability zones. It is specific to a single region.<\/li>\n
  2. Launch Configuration<\/strong>: It is the information needed by the Autoscaling group to launch EC2 instances.<\/li>\n
  3. Scaling Policies and Alarms<\/strong>: It is the set of rules for determining when to scale an instance up or down in an autoscaling group.<\/li>\n
  4. Elastic Load Balancing (optional)<\/strong>: Add a load balancer to the autoscaling group to distribute traffic and scale instances based on scaling policies.<\/li>\n<\/ol>\n

    \"20140105144132\"<\/p>\n

    Here we are taking a use case to create an Autoscaling group with ELB and configure scaling policies<\/a> in which an instance is scaled up when CPU Utilization is greater than 70% and scaled down when CPU utilization is less than 40% over 2 cycles of 60 seconds each.<\/p>\n

    Steps to follow:<\/h2>\n
      \n
    1. Connecting to ELB
      \n<\/b>The first step for accessing ELB is to create connections to the service:<\/p>\n

      [js]import boto
      \nconn = boto.connect_elb()[\/js]<\/p>\n<\/li>\n

    2. Getting all Load Balancers
      \n<\/b>Retrieve existing load balancer information<\/p>\n

      [js]conn.get_all_load_balancers()[\/js]<\/p>\n<\/li>\n

    3. Creating Health Check:
      \n<\/b>To create a load balancer we need to have the following information:
      \n-Specific Port Listeners where ELB will ping to instances.
      \n-HealthCheck or the ELB concept of a heartbeat. ELB uses this health check to see whether your instances are up or down.
      \n-A list of Availability Zones.<\/p>\n

      [js]
      \nimport botofrom boto.ec2.elb import HealthCheck
      \nconn=boto.connect_elb()
      \nhc=HealthCheck(interval=20,healthy_threshold=2,unhealthy_threshold=4,target=’HTTP:80\/health’)
      \n[\/js]<\/p>\n<\/li>\n

    4. Creating Load Balancer
      \n<\/b>Creating load balancer with the health check defined above.<\/p>\n

      [js]
      \nlb=conn.create_load_balancer(‘my_elb’,[‘us-east-1a’,’us-east-1b’],[(80, 80, ‘http’), (443, 8443, ‘tcp’)])
      \nlb.configure_health_check(hc)
      \n[\/js]<\/p>\n<\/li>\n

    5. Creating Launch Configuration
      \n<\/b>Creating a launch configuration for the Autoscaling group.<\/p>\n

      [js]
      \nimport boto.ec2.autoscale
      \nfrom boto.ec2.autoscale import LaunchConfiguration
      \nconn=boto.ec2.autoscale.connect_to_region("us-east-1",profile_name=’selectcloud’)
      \nlc=LaunchConfiguration(name="boto",image_id=’ami-id’,key_name=’key’,security_groups=[security_grpid-1,security-grpid-2],instance_type=\u2019t2.small\u2019)
      \nconn.create_launch_configuration(lc)
      \n[\/js]<\/p>\n<\/li>\n

    6. Getting all Autoscaling Groups
      \n<\/b>Retrieving existing Autoscaling groups.<\/p>\n

      [js]conn.get_all_groups()[\/js]<\/p>\n<\/li>\n

    7. Creating Autoscaling Group
      \n<\/b>Creating an autoscaling group with the launch configuration defined above.<\/p>\n

      [js]
      \nfrom boto.ec2.autoscale import AutoScalingGroup
      \nag=AutoScalingGroup(group_name=’boto_group’,load_balancers=[‘myelb1’],availability_zones=[‘us-east-1c’,’us-east-1b’],launch_config=lc,min_size=1,max_size=3,connection=conn)
      \nconn.create_auto_scaling_group(ag)
      \n[\/js]<\/p>\n<\/li>\n

    8. To view Activities on Autoscaling Group
      \n<\/b>To view activity on an Autoscaling group<\/p>\n

      [js]conn.get_all_activities(ag)[\/js]<\/p>\n<\/li>\n

    9. Scaling a Group Up or Down
      \n<\/b>Creating scale up and scale down policies with cooldown period of 180<\/p>\n

      [js]
      \nscale_up_policy=ScalingPolicy(name=’scale_up’,adjustment_type=’ChangeInCapacity’,as_name=’boto_group’,scaling_adjustment=1,cooldown=180)
      \nscale_down_policy=ScalingPolicy(name=’scale_down’, adjustment_type=’ChangeInCapacity’,as_name=’boto_group’,scaling_adjustment=-1, cooldown=180)
      \nconn.create_scaling_policy(scale_down_policy)
      \nconn.create_scaling_policy(scale_up_policy)[\/js]<\/p>\n<\/li>\n

    10. Fetching ARN(Amazon Resource Name)<\/b>\n

      [js]
      \nscale_down_policy_arn=conn.get_all_policies(as_group=’boto_group’,policy_names=[‘scale_down’])[0]
      \nscale_up_policy_arn=conn.get_all_policies(as_group=’boto_group’,policy_names=[‘scale_up’])[0]
      \n[\/js]<\/p>\n<\/li>\n

    11. Next, we\u2019ll create CloudWatch alarms that will determine when to run the Auto Scaling Policies.<\/b>\n

      [js]
      \nfrom boto.ec2.cloudwatch import MetricAlarm
      \nimport boto.ec2.cloudwatch
      \ncloudwatch=boto.ec2.cloudwatch.connect_to_region(‘us-east-1′,profile_name=’selectcloud’)
      \nalarm_dimensions={"AutoScalingGroupName":"boto_group"}
      \nscale_down_alarm=MetricAlarm(name=’scale_down_cpu’,namespace=’AWS\/EC2′,metric=’CPUUtilization’,statistic=’Average’,comparison='<‘,threshold=’40’,period=’60’, evaluation_periods=2,alarm_actions=[scale_down_policy_arn.policy_arn],dimensions=alarm_dimensions)
      \nscale_up_alarm=MetricAlarm(name=’scale_up_cpu’, namespace=’AWS\/EC2′,metric=’CPUUtilization’, statistic=’Average’,comparison=’>’, threshold=’70’,period=’60’, evaluation_periods=2,alarm_actions=[scale_up_policy_arn.policy_arn],dimensions=alarm_dimensions)
      \ncloudwatch.create_alarm(scale_up_alarm)
      \ncloudwatch.create_alarm(scale_down_alarm)
      \n[\/js]<\/p>\n<\/li>\n<\/ol>\n

      Hope this was useful to you for implementing AWS Autoscaling. The complete Boto script can be downloaded from here\u00a0for a ready reference.<\/p>\n","protected":false},"excerpt":{"rendered":"

      Autoscaling is a service\u00a0in AWS, which is used to launch or terminate an instance based on user-defined policies, health checks, and schedules. There are several ways to configure an auto-scaling group in AWS, here we are focusing on implementing it in python using AWS python module boto. Before Creating \u00a0an Autoscaling Group\u00a0 we have to […]<\/p>\n","protected":false},"author":917,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":29,"footnotes":""},"categories":[1174,2348],"tags":[2098,248,2091,1262,1929,1746,2092,1611,1892,3236,1358,1790],"class_list":["post-36155","post","type-post","status-publish","format-standard","hentry","category-aws-2","category-devops-technology","tag-auto-scaling-policies","tag-aws","tag-aws-autoscaling-groups","tag-aws-cloud-watch","tag-aws-cloud-watch-alarms","tag-aws-elb","tag-aws-launch-configuration","tag-boto","tag-devops","tag-devops-aws","tag-python","tag-python-scripting"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t