CloudWatch setup for CPU and Memory on a Debian 12 AWS EC2 instance to send alerts via email and SMS involves the following steps:

Step 1: Install and Configure the CloudWatch Agent

1. Update your instance and install prerequisites: sudo apt update && sudo apt upgrade -y sudo apt install unzip -y
2. Download the CloudWatch agent: wget https://s3.amazonaws.com/amazoncloudwatch-agent/ubuntu/arm64/latest/amazon-cloudwatch-agent.deb
3. Install the CloudWatch agent: sudo dpkg -i amazon-cloudwatch-agent.deb
4. Configure the CloudWatch agent: Use the following command to generate a configuration file: sudo /opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-config-wizard
   • During the setup, specify:
     • The metrics you want to monitor (e.g., CPU, memory, disk).
     • Log collection if needed.
     • Instance role-based authentication (use an IAM role with CloudWatch permissions).
   The wizard will generate a file at /opt/aws/amazon-cloudwatch-agent/bin/config.json.
5. Start the CloudWatch agent: sudo systemctl start amazon-cloudwatch-agent sudo systemctl enable amazon-cloudwatch-agent
6. Verify the agent is running: sudo systemctl status amazon-cloudwatch-agent

Step 2: Configure CloudWatch Alarms

1. Go to the AWS Management Console:
   • Navigate to CloudWatch > Alarms > Create Alarm.
2. Create a CPU Utilization Alarm:
   • Select the EC2 instance metric.
   • Choose CPUUtilization under the metrics list.
   • Set the threshold, e.g., “If CPUUtilization > 80% for 5 minutes”.
3. Create a Memory Utilization Alarm:
   • Memory metrics are collected via the CloudWatch agent. They will appear under Custom Metrics in CloudWatch.
   • Select the custom memory metric (e.g., CWAgent > Memory > Available).
   • Set the threshold, e.g., “If Available Memory < 500MB for 5 minutes”.
4. Set Actions:
   • For both alarms, select Add Notification > Create a new SNS topic.
   • Name the topic (e.g., CPU-Memory-Alerts) and add your email address.
   • For SMS, add a phone number under Subscribers.
5. Confirm Email Subscription:
   • AWS will send a confirmation email to the address you specified. Open the email and confirm the subscription.

Step 3: Test the Setup

1. Trigger a CPU Spike: Run the following command to increase CPU usage: yes > /dev/null &
   • Wait for the alarm to trigger.
   • Stop the spike with killall yes.
2. Trigger a Low Memory Alert: Allocate memory to simulate low available memory: stress --vm 2 --vm-bytes 90% --timeout 60
3. Verify Notifications:
   • Ensure you receive the alerts via email and SMS when the thresholds are met.

Optional: Use CloudWatch Dashboard

1. Create a CloudWatch Dashboard to view real-time metrics.
   • Go to CloudWatch > Dashboards > Create Dashboard.
   • Add widgets for CPU, memory, and other metrics for better visualization.
2. Save and monitor your instance metrics from a single place.

IAM Role Permissions

Ensure your EC2 instance has an IAM role with the following permissions:

• CloudWatchAgentServerPolicy
• CloudWatchFullAccess
• AmazonSNSFullAccess

Attach the IAM role to your EC2 instance via the IAM Management Console.

JSON Policy for CloudWatch Role allowing the CloudWatch agent access to the EC2 Instance:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "cloudwatch:PutMetricData",
                "ec2:DescribeTags",
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": "*"
        }
    ]
}

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