Analyzing and remediating the configuration of a custom application that is not reporting its statistics

What initial steps would you take to determine why a custom application is not reporting its statistics to AWS CloudWatch?

First, ensure that the application is running and that there are no application-level errors. Then, verify that the necessary IAM roles and permissions are correctly assigned to allow the application to write to CloudWatch. Additionally, check that the AWS SDK or agent being used is correctly configured and that the correct region is selected. AWS CloudWatch Logs Agent should be installed and properly configured if it is being used for log data.

How would you check for network-related issues that might prevent the custom application from sending metrics to CloudWatch?

To troubleshoot network-related issues, I would verify security group and network ACL configurations to ensure that outgoing HTTPS (port 443) traffic to CloudWatch endpoints is allowed. I would also ensure that the VPC has internet access through an Internet Gateway or VPC endpoint for CloudWatch is configured if the resources are in a VPC.

Which AWS service or tool would you use to centrally manage the application’s permissions that could affect statistics reporting?

AWS Identity and Access Management (IAM) is used to centrally manage permissions. I would check the IAM policy attached to the role or user that the application uses to interact with AWS services for the appropriate CloudWatch permissions, such as “CloudWatch:PutMetricData”.

What is the importance of time synchronization in the context of reporting metrics, and how would you ensure time accuracy on your EC2 instances?

Time synchronization is critical for ensuring that the metrics are accurate and correspond with the right time intervals. To ensure time accuracy, I would configure Amazon Time Sync Service on the EC2 instances. It uses a set of NTP servers to deliver highly reliable time.

If the application is supposed to log events using AWS CloudWatch Events, what might be reasons for the metrics not appearing, and how would you address these issues?

Possible reasons for the metrics not appearing include incorrect event pattern configuration, lack of necessary permissions, or a misconfiguration with the event target. I would verify the event pattern rules, ensure that the IAM role has the “events:PutEvents” permission, and check the target configuration for errors.

Can you describe how you would use AWS CloudTrail in conjunction with CloudWatch to troubleshoot the custom application’s reporting issue?

AWS CloudTrail can be used to audit API calls made by the custom application. By looking into CloudTrail logs, I could identify if there were any failed attempts to send metric data, which might show errors or denied requests due to permission issues. I can also filter events in CloudTrail that involve CloudWatch API operations.

How could misconfiguration of AWS Lambda functions or their triggers interfere with the application’s ability to report statistics, and what would you do to remediate this?

If the application uses AWS Lambda for processing, misconfiguration of triggers (e.g., DynamoDB stream, S3 event, or incorrect handling of retries) could lead to failures in the execution or invocation of the function, thus leading to no reported metrics. To remediate this, I would ensure that the Lambda function has the correct trigger configurations, error handling and retry logic is properly set up, and the IAM execution role has the necessary permissions.

What are some potential reasons an EC2 instance would fail to publish custom metrics to CloudWatch, and what tools or strategies would you use to diagnose and fix the problem?

Potential reasons for failure might include lack of IAM permissions, software misconfiguration, lack of network connectivity, or incorrect CloudWatch namespace or metric names. To diagnose the problem, I would use SSH to access the EC2 instance, review application and agent logs, verify the instance’s IAM role and policies, and use the AWS CLI or AWS Management Console to test connectivity to CloudWatch.

When addressing configuration issues of a custom application, what logging information would you look for to ascertain the root cause of the problem?

I would look for error messages, stack traces, or warnings in the application logs that indicate configuration issues or connectivity problems. Additionally, I would review the CloudWatch agent’s logs if it’s being used, to confirm that it’s operating correctly and able to communicate with AWS CloudWatch.

Describe the steps you would take to ensure that the correct metrics are being reported for a custom application running in a containerized environment on Amazon ECS.

To ensure correct metrics reporting for a containerized application on Amazon ECS, I would:
– Check that the Amazon CloudWatch Container Insights is enabled for the ECS cluster.
– Verify that the task definition includes the necessary CloudWatch configuration.
– Confirm that the IAM roles for ECS tasks have the appropriate CloudWatch permissions.
– Ensure that the container agent is running the latest version and is properly configured to send metrics to CloudWatch.
– Analyze the container instance logs to find any errors related to metrics reporting.