CloudWatch (CW) Fundamentals

CloudWatch Service and Architecture

🔧 Collects & manages operational data → provides operational management & monitoring
- Operation data includes service performance, run metrics, logs…
- Core support service used by almost all other AWS services
- Public service
Three main components:
1. CW Metrics = "CW itself” (”Vanilla” CW)
  - e.g. CPU utilization of EC2 instance, disk usage on an on-premise server…
  - Can ingest metrics from AWS products, apps, or on-premises infrastructure
  - Some metrics are gathered natively by AWS products
  - Configuration of a CW Agent is needed for:
    - Collecting metrics inside AWS that are not gathered natively
      - e.g. internal processes in an EC2 instance
    - Collecting metrics outside of AWS
2. CW Logs
  - Can ingest logs from AWS products, apps, or on-premises infrastructure
  - Some logs generated natively by AWS products, other products need CW Agent
3. CW Events
  - Works with AWS services and schedules
  - Generates events which can trigger actions (e.g. send a notification email)
  - Events can be generated based on:
    1. condition (e.g. an EC2 instance is created or terminated)
    2. schedule (e.g. tomorrow at 13:45, or every Friday at 18:00)
  - 💡 The Billing Alarm was set with CW Events → send a notification when billing surpasses a budget
Architecture Diagram

Datapoint = Timestamp + Value (Pair)
- e.g. CPU usage is 98.3% at 08:45:45 on 2019-12-03
Metric = Sequence of datapoints ordered in time = Time-ordered set of datapoints
- e.g. CPU usage, NW I/O, Disk I/O… (in a given time frame)
- ‼️ NOT necessarily related to a single server!
  - e.g. CPU usage will be displaying by default the usage across all EC2 instances! Must specify otherwise if you want to limit to one instance!
- Metric and Datapoints Diagram
Namespace = Name container for monitoring data, contains name-related metrics
- 💡 Keeps things from becoming messy
- Can have any rule-complying name
- e.g. AWS/ ← namespace where all AWS data goes to
  - e.g. AWS/EC2 ← namespace for all EC2 data
Dimensions = Criteria that separate datapoints of same metric into different perspectives
- e.g. Inside AWS/EC2 namespace, separate into dimensions: Instance A, Instance B…
- Powerful & Flexible
- Dimensions and Namespace Diagram
Alarms take actions based on a specific metric reaching specified values/thresholds
- e.g. Send a notification when budget has been exceeded (billing alarm)
- States: INSUFFICIENT DATA (initial state), OK or ALARM
  - alarm uses SNS (Simple Notification System) when the state is ALARM
- Alarm Diagram