How to Monitor and Troubleshoot AWS EC2 Instances Using CloudWatch and AWS CLI

Table of Contents

1. Why Monitoring EC2 Instances is Important
2. Introduction to AWS CloudWatch
3. Setting Up CloudWatch Monitoring for EC2 Instances
   • CloudWatch Default Metrics
   • Custom Metrics for Application Monitoring
4. Troubleshooting EC2 Instances Using AWS CLI
   • Checking EC2 Instance Status
   • Viewing System Logs from AWS CLI
   • Monitoring Instance Metrics from CLI
5. Setting Up Alarms in CloudWatch for Proactive Alerts
6. Best Practices for EC2 Instance Monitoring and Troubleshooting
7. Conclusion

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1. Why Monitoring EC2 Instances is Important

Monitoring EC2 instances is crucial for identifying performance bottlenecks, managing resource consumption, and detecting potential security threats. Without proper monitoring, minor issues like CPU spikes or network latency could escalate into major application outages.By setting up an effective monitoring solution with AWS CloudWatch and using the AWS CLI for troubleshooting, you can track instance performance in real time, automate alarms for critical metrics, and resolve problems quickly.

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2. Introduction to AWS CloudWatch

AWS CloudWatch is a monitoring service that collects and tracks metrics, collects log files, and sets alarms for AWS resources, including EC2 instances. It provides key system-level metrics by default and also supports custom metrics, making it flexible for monitoring application performance.CloudWatch offers the following capabilities for EC2 monitoring:

• Collects default system metrics like CPU utilization, disk I/O, and network traffic.
• Supports custom application metrics.
• Creates alarms based on thresholds.
• Integrates with AWS Lambda to trigger actions based on alarms.

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3. Setting Up CloudWatch Monitoring for EC2 Instances

CloudWatch Default Metrics for EC2 Instances

By default, AWS CloudWatch collects several useful metrics for each EC2 instance, such as:

• CPU Utilization: Shows the percentage of CPU usage on the instance.
• Disk Read/Write Operations: Measures the rate at which the instance reads and writes data from its disks.
• Network In/Out: Displays the number of bytes received or sent through the network interfaces.
• Status Checks: AWS performs automatic checks on both the instance and its underlying host to ensure everything is functioning properly.

You can view these default metrics by navigating to the CloudWatch console, selecting Metrics, and filtering by EC2.

Custom Metrics for Application Monitoring

In addition to default metrics, you may want to track application-specific metrics like memory usage, disk space, or application response time. To do this, you’ll need to use a CloudWatch agent to push custom metrics.

1. Install CloudWatch Agent on EC2 Instance:
   bash

   Copy code

   sudo yum install amazon-cloudwatch-agent

2. Configure the CloudWatch Agent:
   Create a configuration file (config.json) with the custom metrics you want to track. For example, here’s a configuration file to monitor memory and disk space:
   json

   Copy code

   {
"metrics": {
"append_dimensions": {
"InstanceId": "${aws:InstanceId}"
},
"metrics_collected": {
"mem": {
"measurement": [
"mem_used_percent"
],
"metrics_collection_interval": 60
},
"disk": {
"measurement": [
"used_percent"
],
"metrics_collection_interval": 60,
"resources": [
"/"
]
}
}
}
}

3. Start the CloudWatch Agent:
   After configuring the agent, start it with:
   bash

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   sudo /opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-ctl \
-a start \
-m ec2 \
-c file:/path/to/config.json \
-s


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4. Troubleshooting EC2 Instances Using AWS CLI

The AWS CLI provides a powerful set of commands for interacting with your AWS resources. You can use it to quickly troubleshoot EC2 issues by checking instance status, viewing logs, and monitoring metrics.

Checking EC2 Instance Status

To check the status of an EC2 instance using the CLI:This command provides details about both system and instance status checks.

Viewing System Logs from AWS CLI

You can retrieve the system log for an EC2 instance (for example, to debug boot issues) with the following command:This will return the latest system logs, which can help you identify issues during startup.

Monitoring Instance Metrics from CLI

You can use the AWS CLI to retrieve CloudWatch metrics for your instance. For example, to get CPU utilization metrics:This command retrieves average CPU utilization for a specified time period.

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5. Setting Up Alarms in CloudWatch for Proactive Alerts

Setting up CloudWatch Alarms helps ensure you’re notified when instance performance degrades. For example, you can set an alarm to notify you when CPU utilization exceeds 80% for a sustained period.

Creating an Alarm in CloudWatch:

1. Go to CloudWatch Console:
   Navigate to the Alarms section in the CloudWatch console and click Create Alarm.
2. Select Metric:
   Choose the EC2 instance metric (e.g., CPUUtilization) that you want to monitor.
3. Configure Alarm Conditions:
   Set the condition (e.g., CPU utilization greater than 80% for 5 minutes).
4. Set Notification:Configure a notification action (e.g., send an email via SNS) when the alarm is triggered.
5. Save and Activate:Once configured, the alarm will continuously monitor the instance and trigger notifications if conditions are met.

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6. Best Practices for EC2 Instance Monitoring and Troubleshooting

• Monitor Key Metrics Continuously:Ensure critical instance metrics such as CPU, memory, disk, and network I/O are being monitored at all times.
• Set Alarms for Critical Events:Set up CloudWatch Alarms to notify you of high resource utilization, instance failures, or other potential issues.
• Use Automation to Respond to Alarms:Automate responses to alarms (e.g., scaling EC2 instances or restarting services) using AWS Lambda or other tools.
• Log Everything:Ensure that your applications and operating system are properly logging data. Use CloudWatch Logs for centralized logging and monitoring.
• Test Failures Regularly:Perform regular failure simulations (e.g., by stopping instances or creating high-load conditions) to ensure your monitoring system reacts as expected.

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7. Conclusion

Effective monitoring and troubleshooting of AWS EC2 instances using CloudWatch and AWS CLI are essential for maintaining smooth application performance. By setting up proper monitoring and using proactive alarms, you can quickly identify and resolve potential issues before they impact your business.Whether you’re monitoring CPU utilization, managing network traffic, or troubleshooting system failures, the combination of AWS CloudWatch and CLI tools provides the flexibility and power needed to keep your EC2 instances running efficiently.

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