Amazon CloudWatch provides a general purpose timeseries database used to monitor resources and applications in real-time, collecting and tracking metrics and log messages for use in dashboards or alarms and delivering notifications when alarms are raised.


  • Metrics are data points we're monitoring. They can be monitored at various frequencies, which can be adjusted as required (at cost).
  • Alarms can trigger behaviour to remediate problems or alert operators based on metrics falling out of defined thresholds.
  • Events deliver real-time streams of events taking place in a service or on a regular basis, allowing us to respond.
  • Dashboards combine metric visualisations with explanatory text and images.


Namespaces are containers for metrics, allowing isolation between applications.


<60 seconds3 hours
60 seconds (1 minute)15 days
300 seconds (5 minutes)63 days
3600 seconds (1 hour)455 days (15 months)

Higher resolution data points will be aggregated together for long-term storage, degrading over time per the table above.

Data points older than 15 months are removed on a rolling basis. They can't be deleted, but expire after 15 months if no additional data is pushed to them.


A dimension is a name-value pair that is part of a metric's identity and can be used to query it. Each metric can be assigned up to 10 dimensions.

  1. Alarms
  2. Events
  3. Logs
  4. Metrics
  5. Synthetics