CloudWatch is a collection of services that monitor/observe cloud resources via metrics and provide actionable insights.
- CloudWatch monitors the performance of AWS services – a repository service for metric data.
- CloudWatch logs the events and visualizes them.
Amazon CloudWatch
- A CloudWatch metric is a set of data points over time. (ex. CPU Utilization of EC2 instances)
- Metrics can be configured with alarms that can take actions.
- Autoscaling is dependent on CloudWatch to trigger the addition or removal of instances.
Data retention
- one-hour metrics (for 455 days)
- five-minute metrics (for 63 days)
- one-minute metrics (for 15 days)
Monitoring Plans
- Basic: Data is available in 5-minute periods at no charge.
- Detailed: Data is available in 1-minute periods with an additional charge.
CloudWatch Services
CloudWatch is a collection of services: Alarms, Logs, Metrics, and Events.
Alarms
- Insufficient: not enough data
- Alarm: the threshold is breached.
- OK: The metric is within the defined threshold.
- The components of alarms are:
- Metric: The data points being measured
- Threshold: the criteria to check it is normal or abnormal
- Period: How long the state over the threshold is bad before an alarm is generated
- Action: What needs to be done when an alarm is triggered
- SNS Notification
- EC2 Actions: Stop, terminate, or reboot an EC2 instance
- Auto Scaling Actions: Execute an Auto Scaling policy
Metrics
- A time-ordered set of data points
- Exist only in a region where they are created
- Cannot be deleted. But old data are aggregated, and data older than 15 months are dropped.
CloudWatch Components
Namespaces
- a container for ClouldWatch metrics
- The naming convention: aws/service
Dimensions
- A name/value pair that uniquely identifies a metric.
Statistics
- Aggregated metric data over specified periods of time
- Minimum, Maximum, Average, Sum, SampleCount …
CloudWatch and EC2 Instances
CloudWatch does not collect some metrics for EC2 instances. You need to install a CloudWatch agent in the instances.
- Default Metrics:
- CPU Utilization, Disk Reads/Writes, and Network Utilization (Network In/Out)
- Custom Metrics with CloudWatch agents:
- EC2 does not send OS-level metrics to CloudWatch
- Memory utilization, processes, and disk space/swap usages
CloudWatch Logs
CloudWatch Logs is a service for centralizing logs. It stores, monitors, and accesses logs from AWS services and applications.
- “CloudWatch Logs” accepts connections from AWS services (such as EC2, Lambda, or CloudTrail), from API streams (from a custom application), or CloudWatch agents.
- You can review logs as a flow of time-ordered events.
- A metric filter uses pattern matches to analyze logs and create metrics.
- A log event is a timestamp and a raw message.
- A log stream is a sequence of log events with the same source.
- A log group is a container for log streams. It controls retention, monitoring, and access. You can set filters in a group.
CloudWatch Logs Insights
CloudWatch Insights
CloudWatch Insights is an enhanced-service for monitoring some AWS services and your applications It collects, aggregates, and summarizes logs and metrics.
- Container Insights
- for containerized applications and services
- Lambda Insights
- for detailed performance metrics and logs of your lambda functions
- Application Insights
- for resources and work-load specific metrics of your application
CouldWatch Events
CloudWatch Events has been replaced with EventBridge.
Scriptorium 