Create CloudWatch alarms to monitor a NAT gateway - Amazon Virtual Private Cloud
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Create CloudWatch alarms to monitor a NAT gateway

You can create a CloudWatch alarm that sends an Amazon SNS message when the alarm changes state. An alarm watches a single metric over a time period that you specify. It sends a notification to an Amazon SNS topic based on the value of the metric relative to a given threshold over a number of time periods.

For example, you can create an alarm that monitors the amount of traffic coming in or leaving the NAT gateway. The following alarm monitors the amount of outbound traffic from clients in your VPC through the NAT gateway to the internet. It sends a notification when the number of bytes reaches a threshold of 5,000,000 during a 15-minute period.

To create an alarm for outbound traffic through the NAT gateway

  1. Open the CloudWatch console at https://console.amazonaws.cn/cloudwatch/.

  2. In the navigation pane, choose Alarms, All alarms.

  3. Choose Create alarm.

  4. Choose Select metric.

  5. Choose the NATGateway metric namespace and then choose a metric dimension. When you get to the metrics, select the check box next to the BytesOutToDestination metric for the NAT gateway, and then choose Select metric.

  6. Configure the alarm as follows, and then choose Next:

    • For Statistic, choose Sum.

    • For Period, choose 15 minutes.

    • For Whenever, choose Greater/Equal and enter 5000000 for the threshold.

  7. For Notification, select an existing SNS topic or choose Create new topic to create a new one. Choose Next.

  8. Enter a name and description for the alarm and choose Next.

  9. When you done configuring the alarm, choose Create alarm.

As another example, you can create an alarm that monitors port allocation errors and sends a notification when the value is greater than zero (0) for three consecutive 5-minute periods.

To create an alarm to monitor port allocation errors

  1. Open the CloudWatch console at https://console.amazonaws.cn/cloudwatch/.

  2. In the navigation pane, choose Alarms, All alarms.

  3. Choose Create alarm.

  4. Choose Select metric.

  5. Choose the NATGateway metric namespace and then choose a metric dimension. When you get to the metrics, select the check box next to the ErrorPortAllocation metric for the NAT gateway, and then choose Select metric.

  6. Configure the alarm as follows, and then choose Next:

    • For Statistic, choose Maximum.

    • For Period, choose 5 minutes.

    • For Whenever, choose Greater and enter 0 for the threshold.

    • For Additional configuration, Datapoints to alarm, enter 3.

  7. For Notification, select an existing SNS topic or choose Create new topic to create a new one. Choose Next.

  8. Enter a name and description for the alarm and choose Next.

  9. When you are done configuring the alarm, choose Create alarm.

For more information, see Using Amazon CloudWatch alarms in the Amazon CloudWatch User Guide.