AWS EC2 CloudWatch SNS Alert

Create an SNS Topic

Before CloudWatch can send an alert, it needs a “Topic” to send it to.

1. Open the SNS Console.
2. Select Topics > Create topic.
3. Choose Standard, name it (e.g., My-EC2-Alerts), and click Create topic.
4. Once created, click Create subscription:
   • Protocol: Email.
   • Endpoint: Your email address.
5. Important: Check your inbox and click the Confirm Subscription link in the email AWS sends you.

Create the CloudWatch Alarm

Now, you tell CloudWatch what to look for on your EC2 instance.

1. Open the CloudWatch Console.
2. Go to Alarms > All alarms > Create alarm.
3. Click Select metric:
   • Browse to EC2 > Per-Instance Metrics.
   • Find your Instance ID and select the metric CPUUtilization.
4. Specify metric and conditions:
   • Threshold type: Static.
   • Whenever CPUUtilization is…: Greater than 70.
   • Datapoints to alarm: 1 out of 1 (or 2 out of 2 if you want to avoid “flapping” on brief spikes).
5. Click Next.

Configure the Action

This is where you link the alarm to your SNS topic.

1. Alarm state trigger: Select In alarm.
2. Select an SNS topic: Choose Select an existing SNS topic.
3. Send a notification to…: Choose the topic you created in Step 1 (e.g., My-EC2-Alerts).
4. (Optional) You can also add an EC2 action here to “Reboot” or “Terminate” the instance if it hits this threshold, though usually, you just want the email first.
5. Click Next, give the alarm a name (e.g., High-CPU-Alert-Instance-X), and click Create alarm.