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

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

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