Amazon Cloudwatch Notes

Overview

  • real-time monitoring of AWS services & the applications that run on them
  • metrics: variables you want to measure for your resources and applications
  • alarms: rules that you define that send notifications or automatically make changes to the resources you are monitoring
  • basic monitoring: a service sends data points to CloudWatch every five minutes
  • detailed monitoring: a service sends data points to CloudWatch every minute
  • source: http://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch_architecture.html

Amazon Cloudwatch Architecture

Concepts

Metrics - a time-ordered set of data points that are published to CloudWatch - can be custom, or AWS-service specific defaults (e.g. EC2 CPU usage consumption) - you can receive statistics about those data points as an ordered set of time-series data - uniquely identified by: name, namespace, dimension(s) - metric data is stored for 2 weeks

Namespaces - containers for metrics - Metrics in different namespaces are isolated from each other, so that metrics from different applications are not mistakenly aggregated into the same statistics

Dimensions - name/value pair that helps to identify a metric - “Every metric has specific characteristics that describe it, and you can think of dimensions as categories for those characteristics” - CloudWatch treats each unique combination of dimensions as a separate metric - examples: - Server=Prod,Domain=Frankfurt - Server=Prod,Domain=Rio

Metric Dimensions

Units - a statistic’s unit of measure - e.g. Seconds, Bytes, Bits, Percent, Count, Bytes/Second

Statistics - metric data aggregations over specified periods of time - Aggregations are made using the namespace, metric name, dimensions, and the data point unit of measure, within the time period you specify

Periods - A period is the length of time associated with a specific Amazon CloudWatch statistic - A period can be as short as one minute (60 seconds) or as long as one day (86,400 seconds)

Aggregation - Amazon CloudWatch doesn’t differentiate the source of a metric…allowing you to [for example] get the statistics for minimum, maximum, average, and sum of all requests across your application

Alarms - Alarms can automatically initiate actions on your behalf, based on parameters you specify - An alarm watches a single metric over a specified time period, and performs one or more actions based on the value of the metric relative to a given threshold over a number of time periods

Regions - Amazon CloudWatch does not aggregate data across regions - metrics are completely separate between regions