What is CloudWatch?
CloudWatch is AWS's monitoring and observability service. It collects metrics, logs, and events from all your AWS resources and applications, giving you a complete picture of what's happening in your infrastructure.
Think of CloudWatch as the dashboard of your car. It shows you speed, fuel level, engine temperature, and warning lights. Without it, you'd be driving blind. CloudWatch does the same thing for your cloud resources.
Metrics
CloudWatch metrics are time-series data points like CPU utilization, network traffic, or request latency. AWS services automatically send metrics to CloudWatch — EC2 sends CPU and disk metrics, RDS sends database metrics, and so on.
You can view metrics in the console, create dashboards for visual monitoring, and set alarms when metrics cross thresholds. For example, alert me when CPU stays above 80% for 5 minutes.
Logs
CloudWatch Logs collects and stores log files from your EC2 instances, Lambda functions, containers, and other services. You can search, filter, and analyze logs without logging into individual servers.
aws logs create-log-group --log-group-name /my/app/logs
aws logs put-log-events \
--log-group-name /my/app/logs \
--log-stream-name my-stream \
--log-events timestamp=1234567890,message="Application started"The CloudWatch agent installed on EC2 instances automatically collects system and application logs. It's like having a central log server that works across your entire infrastructure.
Alarms
Alarms watch a metric and take action when it crosses a threshold. You can send notifications (SNS), trigger auto-scaling, or invoke Lambda functions. Alarms are your early warning system.
Set up alarms for critical metrics: high CPU, low disk space, elevated error rates, or unusual network traffic. Catch problems before your users do. An alarm that fires at 3 AM is better than a customer complaint at 9 AM.
CloudWatch Dashboards
Dashboards let you create custom visualizations of your metrics. Arrange widgets showing different metrics on a single page — like a command center for your infrastructure.
Create separate dashboards for different purposes: one for application health, one for cost monitoring, one for security events. Dashboards update in real time, giving you a live view of your environment.