Monitoring DynamoDB with CloudWatch

Amazon CloudWatch is a monitoring service provided by AWS that allows us to collect and track metrics, collect and monitor log files, and set alarms. We can use CloudWatch to monitor Amazon DynamoDB tables and view details about throughput, utilization, item counts, and more. In this tutorial, we will learn how to monitor DynamoDB using CloudWatch.

Syntax

The basic syntax for monitoring DynamoDB with CloudWatch is as follows:

cloudwatch monitor put-metric-alarm \
--alarm-name "AlarmName" \
--metric-name "MetricName" \
--namespace "AWS/DynamoDB" \
--statistic SampleCount \
--period 300 \
--evaluation-periods 1 \
--threshold 1 \
--comparison-operator GreaterThanOrEqualToThreshold \
--dimensions Name=TableName,Value=TableName \
--alarm-actions ARN-of-the-SNS-topic

Example

Let's consider an example of how to monitor a DynamoDB table using CloudWatch. We will create a metric for a table that will notify us whenever the number of failed requests exceeds a limit.

cloudwatch monitor put-metric-alarm \
--alarm-name "FailedRequestsAlarm" \
--metric-name "ProvisionedWriteCapacityUnits" \
--namespace "AWS/DynamoDB" \
--statistic Sum \
--period 60 \
--evaluation-periods 5 \
--threshold 10 \
--comparison-operator GreaterThanOrEqualToThreshold \
--dimensions Name=TableName,Value=Table1 \
--namespace "AWS/DynamoDB" \
--alarm-actions arn:aws:sns:us-east-1:XXXXX:my-topic

In the above example, we created an alarm named 'FailedRequestsAlarm' that will notify us if the number of failed requests exceeds a limit for 'Table1'. The alarm specification includes the following:

• alarm-name : The name of the alarm we want to create.
• metric-name : The name of the metric we want to monitor. In this case, it's 'ProvisionedWriteCapacityUnits'.
• namespace : The namespace we want to monitor. For DynamoDB tables, it is 'AWS/DynamoDB'.
• evaluation-periods : The number of consecutive periods that must fail to trigger the alarm. In this case, it's five.
• threshold : The numeric value at which the alarm is triggered.
• comparison-operator : The logic operator that compares actual data points to the threshold. In this case, it is GreaterThanOrEqualToThreshold.
• dimensions : It specifies the name and value of the dimensions you want to include in the metric. In our case, we want to include tablename.

Output

The alarm will be triggered if the specified condition is met, and we will receive a notification message as set in the alarm-actions.

Explanation

DynamoDB provides metrics that we can monitor to help us understand the workload pattern and usage of the table. These metrics can be used to set alarms that will notify us if the specified threshold is crossed. In the example above, we created a metric that is monitoring the number of provisioned write capacity units and set an alarm if the number of failed requests exceeds a limit. We set the alarm to trigger if the number of failed requests exceeds a limit for five consecutive periods.

Use

We can use CloudWatch to monitor our DynamoDB tables, view details about throughput, utilization, item counts, and more. We can use the insights gained from monitoring to optimize our table performance and reduce costs. By setting alarms on certain metrics, we can be alerted whenever our table is experiencing performance or capacity issues.

Important Points

• CloudWatch can only track the metrics specified by Amazon for DynamoDB tables.
• We cannot track custom metrics unless we use CloudWatch custom metrics feature.
• DynamoDB stores metrics in the AWS/DynamoDB namespace.

Summary

In this tutorial, we learned how to monitor DynamoDB tables with CloudWatch. We learned about the basic syntax and the example of creating an alarm to monitor the number of failed requests for a table. Monitoring DynamoDB tables with CloudWatch can help us understand the workload pattern and usage of the table. With the help of CloudWatch alarms, we can be promptly alerted if a significant event happens with our table.