CloudWatch Agent

What is CloudWatch Agent?

The CloudWatch agent is a software package that enables you to collect more system-level metrics from EC2 instances and on-premises servers. It provides enhanced monitoring capabilities beyond the default CloudWatch metrics.

Key Capabilities

Collect system-level metrics (memory, disk, processes)
Collect custom metrics from applications
Collect logs from instances and on-premises servers
Support for both Linux and Windows

Installation Methods

Command Line

Download and install using wget or curl commands from S3 bucket

Systems Manager

Use AWS-ConfigureAWSPackage document to install on multiple instances

CloudFormation

Include agent installation in infrastructure as code templates

System Metrics Collected

Memory Metrics

mem_used_percent - Memory utilization
mem_available - Available memory
mem_used - Used memory
swap_used_percent - Swap utilization

Disk Metrics

disk_used_percent - Disk space utilization
disk_free - Free disk space
disk_inodes_free - Available inodes

Process Metrics

procstat_cpu_usage - Process CPU usage
procstat_memory_rss - Process memory
procstat_num_threads - Thread count

Configuration

The agent uses a JSON configuration file that defines what metrics and logs to collect.

Configuration Sections

agent: General agent settings
metrics: Metrics collection configuration
logs: Log collection configuration
traces: X-Ray trace collection (optional)

Configuration Storage

Store configuration in Systems Manager Parameter Store for centralized management and easy deployment across multiple instances.

Log Collection

Supported Log Types

Application logs
System logs (/var/log/messages, /var/log/syslog)
Custom application logs
Windows Event Logs
IIS logs

Log Configuration

Specify log file paths, log group names, log stream names, and timestamp formats in the configuration file.

IAM Permissions

Required Permissions

cloudwatch:PutMetricData - Send metrics
logs:CreateLogGroup - Create log groups
logs:CreateLogStream - Create log streams
logs:PutLogEvents - Send log events
ssm:GetParameter - Retrieve configuration from Parameter Store

Managed Policy

Use CloudWatchAgentServerPolicy managed policy for EC2 instances and on-premises servers.

On-Premises Support

The CloudWatch agent can be installed on on-premises servers to monitor hybrid environments.

Requirements

IAM user credentials with appropriate permissions
Network connectivity to CloudWatch endpoints
Supported operating system (Linux or Windows)

Best Practice

Use Systems Manager for centralized management of on-premises servers with the agent.

Agent Management

Start/Stop Commands

Start: amazon-cloudwatch-agent-ctl -a fetch-config -m ec2 -s
Stop: amazon-cloudwatch-agent-ctl -a stop
Status: amazon-cloudwatch-agent-ctl -a query

Configuration Updates

Update configuration in Parameter Store and restart agent to apply changes across all instances.

Troubleshooting

Check agent logs at /opt/aws/amazon-cloudwatch-agent/logs/ for debugging issues.

Best Practices

✓ Use Parameter Store

Store agent configuration in Systems Manager Parameter Store for centralized management

✓ Monitor Agent Health

Create CloudWatch alarms to monitor agent status and metric delivery

✓ Use IAM Roles

Attach IAM roles to EC2 instances instead of using access keys

✓ Optimize Collection Intervals

Balance monitoring granularity with cost by adjusting metric collection intervals

Exam Tips

Key Point

CloudWatch agent is required to collect memory and disk metrics from EC2 instances - these are NOT available by default

Remember

Agent can be used on both EC2 instances and on-premises servers for hybrid monitoring

Important

Use Systems Manager Parameter Store to centrally manage agent configurations across multiple instances