AWS CloudWatch Overview

Amazon CloudWatch is a monitoring service for AWS cloud resources and the applications you run on AWS. You can use CloudWatch to gain system-wide info on resource utilization, application performance, and operational health, collect and track metrics, collect and monitor log files, set alarms, and automatically react to changes in your AWS resources.

CloudWatch Features Overview

CloudWatch can monitor AWS resources such as EC2 instances, DynamoDB tables, and RDS DB instances, as well as custom metrics generated by your applications and services, and any log files your applications generate. 

CloudWatch Events delivers a near real-time stream of system events that describe changes in AWS resources such as EC2 instances, AWS Lambda functions, Amazon Kinesis streams, Amazon ECS tasks, Step Functions state machines, Amazon SNS topics, Amazon SQS queues, or built-in targets.

You can use CloudWatch Logs to monitor, store, and access your log files from EC2 instances, AWS CloudTrail, and other sources. 

The CloudWatch Alarms feature allows you to watch CloudWatch metrics and to receive notifications when the metrics fall outside of the levels (high or low thresholds) that you configure. You can attach multiple Alarms to each metric and each one can have multiple actions.

CloudWatch Pricing Overview

Some of CloudWatch features are free within certain limits, but some are not. For example, customers receive 3 dashboards of up to 50 metrics each per month at no additional charge. You can read more about the CloudWatch pricing at https://aws.amazon.com/cloudwatch/pricing/.

Using CloudWatch With EC2 (Important points / Exam tips)

1. In the EC2 metrics section, you will find CPU, Disk, Network and Status metrics, but not Memory.

2. Standard EC2 monitoring by CloudWatch is 5 minutes.

3. Detailed EC2 monitoring by CloudWatch is 1 minute. This is not free.

4. CloudWatch support all EC2 instances and should work with any operating system currently supported by the EC2 service.

CloudTrail vs. CloudWatch

1. While CloudWatch is mostly for monitoring performance related things, CloudTrail is mainly used for auditing purposes.

2. AWS CloudTrail is a service that enables governance, compliance, operational auditing, and risk auditing of your AWS account.

3. With CloudTrail, you can log, continuously monitor, and retain events related to API calls across your AWS infrastructure.

4. CloudTrail provides a history of AWS API calls for your account, including API calls made through the AWS Management Console, AWS SDKs, command line tools, and other AWS services. This history simplifies security analysis, resource change tracking, and troubleshooting.

Important Points (Exam Tips)

1. You can always retrieve metrics data for any Amazon EC2 instance based on the retention schedules. 

   1. However, the CloudWatch console limits the search of metrics to 2 weeks after a metric is last ingested to ensure that the most up to date instances are shown in your namespace.

2. You can access the metrics data for a terminated Amazon EC2 instance or a deleted Elastic Load Balancer. Amazon CloudWatch stores metrics for terminated Amazon EC2 instances or deleted Elastic Load Balancers for 15 months.

Open Questions

1. Is the minimum time interval granularity for the data that Amazon CloudWatch receives and aggregates 1 minute? Else answer the correct time granularity.