Automate alerts with AWS CloudWatch: Stop guessing about infrastructure health

CloudWatch collects metrics. Alarms watch those metrics. When they breach thresholds, actions trigger. Alerting + automation = infrastructure that fixes itself.

Basic alarms

CPU usage above 80%: send SNS notification.

Application latency above 500ms: send Slack message.

Disk usage above 90%: trigger Lambda to clean up logs.

Thresholds should be based on application requirements, not arbitrary numbers.

SNS notifications

SNS sends alerts via email, SMS, Slack, PagerDuty.

Configure SNS topic. Subscribe endpoints (emails, Slack webhook). Configure CloudWatch alarm to send to SNS.

Test before production. Make sure notifications actually arrive.

Auto Scaling integration

Metric breaches can trigger scaling actions automatically.

CPU above 70% for 2 minutes: add 2 instances.

CPU below 30% for 10 minutes: remove 1 instance.

Balances availability and cost.

Custom metrics

Built-in metrics (CPU, memory, disk) are limited. Push custom metrics.

Application latency. Database query time. Cache hit rate. Any metric you can measure.

Use CloudWatch PutMetricData. Create alarms on custom metrics.

Composite alarms

Combine multiple metrics. "Alert if (CPU > 80% OR memory > 85%) AND (application latency > 500ms)".

Reduces noise. Single high metric isn't worth alerting. Multiple suggests real problem.

Cost

Basic monitoring: free. Detailed monitoring (1-minute intervals): £0.10 per metric.

Custom metrics: £0.30 per metric per month.

Alarms: free.

API requests: small per-request charge.

Where Critical Cloud comes in

CloudWatch alarms are powerful but can become noise machines. Too many alerts, nobody responds.

We help you set meaningful thresholds. You see real problems, not false positives.

If alarm fatigue is a problem, see how Critical Support works.