Using AWS CloudWatch Custom Metrics and EC2 Auto Scaling -VSocial Infrastructure


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I gave a presentation at the AWS User Group, Singapore on 24 Oct 2013 explaining how we used EC2 Auto Scaling with CloudWatch Custom Metrics for our product.

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Using AWS CloudWatch Custom Metrics and EC2 Auto Scaling -VSocial Infrastructure

  1. 1. Auto Scaling Spot Instances with Custom CloudWatch Metrics AWS Singapore User Group Chris Drumgoole Head, Product Management
  2. 2. Agenda • Quick overview of VSocial • Infrastructure Scaling Needs • Overview of EC2 Auto Scaling with AWS – Scaling from CloudWatch • Configuring Auto Scaling Launch Configs, Groups, and Policies • Creating your own CloudWatch Metric • Bringing it all together 2
  3. 3. OVERVIEW
  4. 4. VSocial Overview • “Social Media Enterprise Command Center” • Core Features: – Social CRM – Social Media Community Management • Community Managers use tool to manage FB and TW communities • Tool helps manage conversations from multiple Social Media accounts
  5. 5. A glance at the infrastructure… Database Cluster This needs to scale! Front-End Application Server Cluster Data Pull Data Pull AWS SQS Data Pull Data Pull AWS SNS Data Pull Data Pull Load Balancer Public Visitors
  6. 6. Infrastructure Scaling Needs • Timely Conversation Data Pulls from Social Networks • Data Pull Processes can take longer due to: – Increased activity on channel (more tweets or FB Messages) – Network Latency • Slowdowns will cascade across all requests Requirement: Way to automatically adjust compute resources when needed based on real-time performance data, 24/7
  7. 7. SOLUTION
  8. 8. Introducing Auto Scaling (EC2) • AWS allows two types of Auto Scaling: – Minimal Configuration and Management directly from a CloudWatch Alarm – More advanced via SDK • AWS Supports auto scaling On-Demand or Spot Instances, depending on needs
  9. 9. Spot Instances vs. On Demand Instances • Bidding System • Considerably cheaper than On Demand* – Micro Instances: • On Demand Pricing @ $0.02/hr  ~$14.40/mth • Spot Pricing @ >$0.004/hr  ~$2.88/mth – Small Instances: • On Demand Pricing @ $0.08/hr  ~$57.60/mth • Spot Pricing @ >$0.01/hr  ~$7.20/mth • Spot Instances not guaranteed • Great for non-mission critical tasks * All prices in USD for resources in the Asia Pacific Singapore Region
  10. 10. Spot Instances and Our Needs • We need to be able to scale up data pull instances so we can keep up with volume (and mitigate slowdowns) • It’s ok if the machine are taken away from us, we’ll just request more. • Cost Savings is essential
  11. 11. AWS-Managed Scaling with CloudWatch
  13. 13. Configuring Auto Scaling Before you can finish setting up the CloudWatch Auto Scaling, you need to follow these steps: 1. 2. 3. 4. Install the AWS CLI tools on your trusty Linux box Create an Auto Scaling Launch Config Create an Auto Scaling Group Create Scale Out (Up) and In (Down) Policies
  14. 14. Configuring Auto Scaling: Launch Configurations Defines the type of Instance to create • Create an AMI • Launch Config links to an AMI • Define Instance Type • Define max bid price (in USD, /hr) • Turn off Monitoring! $as-create-launch-config MyLaunchConfigName --image-id ami-123ab456 --instance-type t1.micro --spot-price 0.025 --key our_key_name --monitoring-disabled
  15. 15. Configuring Auto Scaling: Scaling Groups • Create a Load Balancer to “hold” these launch configs • State what AZ zones you want these to be launched in • # Instances Lower and Upper bounds • Meta Configuration • Link to the Launch Configuration $as-create-auto-scaling-group MyASGroupName --availability-zones apsoutheast-1a,ap-southeast-1b --default-cooldown 120 --load-balancers VSocialCrons --min-size 1 --max-size 45 --tag="k=Name, v=SQSProcessor, p=true" --launch-configuration MyLaunchConfigName
  16. 16. Configuring Auto Scaling: Policies • Need both Up and Down policies • Link to the Auto Scaling Group • Define whether it’s an addition or subtraction for “adjustment” $as-put-scaling-policy MyPolicyName-add1 --auto-scaling-group MyASGroupName --adjustment=1 --type ChangeInCapacity --cooldown 300 $as-put-scaling-policy MyPolicyName-del1 --auto-scaling-group MyASGroupName --adjustment=-1 --type ChangeInCapacity --cooldown 600
  17. 17. • Now you’re ready to configure your CloudWatch Alarms to utilize the auto scaling configuration! • But wait…
  19. 19. We need a custom metric!
  20. 20. Creating a CloudWatch Custom Metric • Caveats: – Custom Metrics can be stored as frequent as every 5 minutes – After a while old data will be truncated • Steps – Install the AWS SDK for your favorite language – Write simple script to calculate and store metric – Schedule script by cron • Code Sections: – Set Up – Metric Data Pulls – Store New Metric
  21. 21. Custom Metric Code – Set Up // Constants define("CW_NAMESPACE", "Vocanic/VSocial"); define("CW_MONITORING_AWS_KEY_ID", "XXXXXXXXXXXXXXXXX"); define("CW_MONITORING_AWS_SECRET_ACCESS_KEY", "YYYYYYYYYYYYYY YYY"); // Includes include '/usr/lib/php5/amazon/sdk-'; // Configure options for CloudWatch object $options = array(); $options["key"] = CW_MONITORING_AWS_KEY_ID; $options["secret"] = CW_MONITORING_AWS_SECRET_ACCESS_KEY; // Set up Amazon Objects $cw = new AmazonCloudWatch($options); $cw->set_region(AmazonCloudWatch::REGION_SINGAPORE);
  22. 22. Custom Metric Code – Define Time Bounds // Define time bounds for pulling metric data // We're only interested in the most recent metric // These particular metrics are stored every 5 minutes) $endTime = time(); // Store current unix time in end time variable $startTime = $endTime - 599; // Subtract 1 second less than 10 minutes $endTime = date("j F Y H:i", $endTime); $startTime = date("j F Y H:i", $startTime);
  23. 23. Custom Metric Code – Pull Metric Values // Get Num Deleted Metric $NumberOfMessagesDeletedMetric = $cw->get_metric_statistics( 'AWS/SQS', // CloudWatch Namespace of Metric 'NumberOfMessagesDeleted', // Name of Metric $startTime, $endTime, // Timestamp bounds for pulling set of metrics 60, // Attempt to get a number every 60 seconds, but in reality, it's every 5 min 'Sum', // Statistics: Get Sum value 'Count', // Unit: Get a count of the values array('Dimensions' => array(array('Name' =>'QueueName', 'Value' => 'My_SQS_Queue_Name'))) // Define which SQS Queue you want this metric for ); $NumberOfMessagesDeleted = $NumberOfMessagesDeletedMetric->body>GetMetricStatisticsResult->Datapoints[0]->member->Sum; *Repeat for Number Sent Metric
  24. 24. Custom Metric Code – Store New Metric // Get Timestamp for storing in our custom metric so that timing can match up $TimeStamp = $NumberOfMessagesSentMetric->body>GetMetricStatisticsResult->Datapoints[0]->member->Timestamp; // Get Difference of Sent versus Deleted $SentVSDeleted = $NumberOfMessagesSent $NumberOfMessagesDeleted; // Send metric to CloudWatch $response = $cw->put_metric_data(CW_NAMESPACE, array( array( 'MetricName' => 'DataPullQueueSentvsDel', 'Timestamp' => $TimeStamp, 'Value' => $SentVSDeleted )));
  25. 25. AWS CloudWatch Custom Metric
  26. 26. Custom Metric in Practice
  27. 27. Scaling Deciding Factors • For each scaling policy, you need to creating a specific policy from the CLI – – – – Queue Delta >100 for 5 min, Add 1 Instance Queue Delta >350 for 5 min, Add 2 Instances Queue Delta >1000 for 5 min, Add 4 Instance Queue Delta < 10 for 60 minutes, Remove 1 Instance
  28. 28. Danger! Queue Delta > 1000!! When Alarms are hit, Auto Scale Out policy is triggered, instan ces are created 4 Instances Created ??
  29. 29. Thanks! • Questions?