AWS Classroom Series – 23/Jun/2021

Cloud Watch Concepts

• Namespaces:
  • Namespace is a container for CloudWatch metrics.
  • AWS namespaces typically use the following naming conventions AWS/service
  • List of AWS Namespaces Refer Here
• Metrics:
  • A Metric represents the time-ordered set of data points that are published to CloudWatch
  • By default, AWS services provide free metrics for resources
  • Viewing Available Metrics Refer Here
  • Publishing Custom Metrics Refer Here
  • Timestamp: Each metric data point must be associated with a time stamp. Timestamps are datetime objects. Although it is not required, it is recommended to use Coordinated Universal Time (UTC)
  • Metrics Retention:
    • Data points with a period less than 60 seconds are available for 3 hours. These data points are called as high-resolution custom metrics
    • Data points with period of 60 seconds are available for 15 days
    • Data points with a period of 300 seconds are available for 63 days
    • Data points with a period of 3600 seconds are available for 455 days (15 months)
• Dimensions:
  • A dimension is a name/value pair that is part of identity of the metric.
• Resolution:
  • Each metric is one of the following
    • Standard resolution: with data having one-minute granularity
    • High resolution: with data at a granularity of one second
• Statistics:
  • Minimum
  • Maximum
  • Sum
  • Average
  • Sample Count
  • Percentile
• Percentiles
• Alarms:
  • An alarm watches a single metric over a specified period of time and performs one or more specified actions based of the value of metric relative to threshold over time.
  • Example: Alarm: High CPU (when average cpu utilization > 80% for last 5 minutes )

  # Situation: Machine was create 2 minutes ago
  Now the alarm state would be insufficient data
  
  # Situtation: Average cpu utilization for last 5 mins is 50%
  Now the alarm state would be OK
  
  # Situation : Average cpu utilization for last 5 mins is 90%
  Now the alarm state would be Alarm
  

  • Using CloudWatch alarms, we can perform actions when the alarms are in state alarm

  when cpu utilization > 80 % for last 5 minutes => send mail to admins
  
  when cpu utilization < 10 % for last 60 minutes => shutdown the ec2 instance.
  
  

Scenario 1: Restart the ec2 instance during high cpu

• Steps

Scenario 2: Stop the ec2 instance during less cpu

• Shutdown the ec2 instance if the cpu utilization is less than 5 % for the last 30 minutes

Simple Notification Service

• Navigate to SNS
• Lets create an email subscription
• Now lets create an email notification when CPU utilization is less

Exercise

• Create an SNS Topic called as Admin Topic
• Create an Email Subscription to your email id and confirm the subscription
• Create a Cloud watch alarm for the below scenarios
  • For High CPU of ec2 instance
  • For low CPU of ec2 instance
  • For More number or Database connections in RDS (Database Connections > 50 )
  • For zero connections in RDS