How to log application data

Logging application data is an important facet of application management and performance optimization. It is primarily a way to trace or debug any errors, as well as to analyze the usage trends for capacity planning. When it comes to the AWS Certified Data Engineer – Associate (DEA-C01) exam, understanding how to log application data is pertinent to the effective management of data within Amazon Web Services (AWS).

AWS provides numerous services for logging application data, including Amazon CloudWatch, AWS CloudTrail, and AWS X-Ray. These services provide a detailed view into your application’s behaviour by collecting and processing raw log data from your services.

1. Amazon CloudWatch:

CloudWatch provides operational and system-wide visibility into resource utilization, application performance and operational health. With CloudWatch, you can collect and track metrics, collect and monitor log files, set alarms, and automatically react to changes in your AWS resources.

You can use the following example to publish custom metrics to CloudWatch using the AWS SDK for Java.

<code>
import com.amazonaws.services.cloudwatch.AmazonCloudWatch;
import com.amazonaws.services.cloudwatch.AmazonCloudWatchClientBuilder;
import com.amazonaws.services.cloudwatch.model.Dimension;
import com.amazonaws.services.cloudwatch.model.MetricDatum;
import com.amazonaws.services.cloudwatch.model.PutMetricDataRequest;
import com.amazonaws.services.cloudwatch.model.PutMetricDataResult;
import com.amazonaws.services.cloudwatch.model.StandardUnit;

public class PublishMetrics {
public static void main(String[] args) {
final String usageMetricName = “PageViewCount”;
final AmazonCloudWatch cw =
AmazonCloudWatchClientBuilder.defaultClient();

MetricDatum datum = new MetricDatum()
.withMetricName(usageMetricName)
.withUnit(StandardUnit.None)
.withValue(Double.parseDouble(“1.0”))
.withDimensions(new Dimension()
.withName(“Page”)
.withValue(“HomePage”));

PutMetricDataRequest request = new PutMetricDataRequest()
.withNamespace(“SITE/TRAFFIC”)
.withMetricData(datum);

PutMetricDataResult response = cw.putMetricData(request);
System.out.printf(“Successfully put metric data: %s\n”, response.toString());
}
}
</code>

2. AWS CloudTrail:

CloudTrail is a service that enables governance, compliance, operational auditing, and risk auditing of your AWS account. You can continuously monitor and retain account activity related to actions across your AWS infrastructure.

3. AWS X-Ray:

X-Ray helps developers analyze and debug production, distributed applications. It provides insights into how your application is performing and shows where bottlenecks are slowing you down.

Each of these services play different roles, and together they provide a comprehensive array of tools to log, track, and analyze application data in AWS. Mastering these services is integral to becoming an AWS Certified Data Engineer. Going forward, make sure to practice with these services to gain hands-on experience. Remember, the DEA-C01 exam focuses extensively on practical scenarios and use-cases, so the more you practice, the better you’ll perform.

Practice Test

True or False: AWS CloudWatch is a service that is used to transmit and log data.

• True
• False

Answer: True.

Explanation: AWS CloudWatch is a monitoring service that collects logs as well as metrics from the services and applications running on the AWS infrastructure, to provide real-time insights.

What are the levels of logging that can be set in an application? (Multiple Select)

• A. Error
• B. Information
• C. Medium
• D. Warning
• E. Node

Answer: A, B, D.

Explanation: Error, Information, and Warning are common levels of logging which indicate the severity or priority of the log entries. Node is not a logging level.

Which AWS service can be leveraged to automatically scale your applications in response to logged data?

• A. AWS Lambda
• B. AWS Batch
• C. AWS Auto Scaling
• D. AWS Elastic Beanstalk

Answer: C. AWS Auto Scaling.

Explanation: AWS Auto Scaling monitors your applications and automatically adjusts capacity to maintain steady, predictable performance at the lowest possible cost.

True or False: There is no need to design a data lifecycle when logging application data.

• True
• False

Answer: False.

Explanation: A well-planned data lifecycle is crucial when logging application data. This includes planning for data ingestion, storage, processing, and disposal.

How does AWS CloudTrail help in logging application data?

• A. It monitors your AWS deployments.
• B. It delivers event history of your AWS account activity.
• C. It performs data processing operations.
• D. None of the above.

Answer: B. It delivers event history of your AWS account activity.

Explanation: AWS CloudTrail is a service that enables governance, compliance, operational auditing, and risk auditing of your AWS account. It specifically delivers event history including actions taken through the AWS Management Console, AWS SDKs, command line tools, and other AWS services.

In AWS, which of the following is NOT an option for encrypting log files?

• A. AWS Encryption SDK.
• B. S3 Server Side Encryption (SSE).
• C. AWS Key Management Service.
• D. AWS ElasticSearch Encryption.

Answer: D. AWS ElasticSearch Encryption.

Explanation: AWS ElasticSearch Encryption is not a real service. However, log files can be encrypted using methods such as AWS Encryption SDK, S3 Server Side Encryption (SSE), and AWS Key Management Service.

True or False: You need to manually set up a centralized logging system when using AWS CloudWatch.

• True
• False

Answer: False.

Explanation: AWS CloudWatch automatically aggregates and stores logs from your AWS resources, providing a centralized system without the need for additional set-up.

What AWS service allows querying and analyzing log data?

• A. AWS Athena
• B. AWS SageMaker
• C. AWS Glue
• D. AWS Lex

Answer: A. AWS Athena.

Explanation: AWS Athena is an interactive query service that makes it easy to analyze data in Amazon S3 using standard SQL.

What is the role of AWS Glue in logging application data?

• A. It performs ETL operations.
• B. It stores log files.
• C. It visualizes logs in a dashboard.
• D. None of the above.

Answer: A. It performs ETL operations.

Explanation: AWS Glue is a fully managed extract, transform, and load (ETL) service that makes it easy to prepare and load your data for analytics.

True or False: AWS X-Ray service helps in logging and reviewing application behavior.

• True
• False

Answer: True.

Explanation: AWS X-Ray helps developers analyze and debug distributed applications, such as those built using a microservices architecture. It allows for logging and analyzing specific segments of application behavior.

Interview Questions

What AWS service allows developers to log, monitor, and retain application data?

Amazon CloudWatch is the AWS service that allows developers to collect monitoring and operational data in form of logs, metrics, and events, providing a unified view of AWS resources, applications and services that run on AWS.

How can application logs be retained for longer periods for compliance in AWS?

Application logs can be retained for longer periods by shipping them to Amazon S3 using an AWS Lambda function.

What is the AWS service that transforms, loads, and delivers streaming data like application logs in realtime?

Amazon Kinesis Data Firehose is the AWS service designed to load streaming data into data lakes, data stores and analytics tools.

How to centrally manage application log data?

By sending your application log data to AWS CloudWatch Logs, you can manage them centrally.

In which format should your logs be emitted to get the most out of CloudWatch?

Logs should be emitted in JSON format to make them searchable and to gain additional functionality in AWS CloudWatch.

How to alert on specific phrases, values or patterns in your log data in AWS?

AWS CloudWatch Logs Insights allows you to perform complex queries and alert on specific phrases, values or patterns in your log data.

What AWS service allows you to analyze log data and troubleshoot the causes of specific issues within your application?

Amazon CloudWatch Logs Insights is a fully managed service that allows you to analyze log data and identify specific issues within your application for troubleshooting.

What are the three main types of data you can monitor with Amazon CloudWatch?

The three main types of data you can monitor with Amazon CloudWatch are logs, metrics, and events.

How to send application logs from EC2 instances to CloudWatch Logs?

EC2 instances can send logs to CloudWatch Logs using the CloudWatch Logs agent.

What are the benefits of monitoring application data with Amazon CloudWatch?

Benefits of monitoring application data with Amazon CloudWatch include being able to gain a unified view of your applications, system-wide visibility, detailed insights related to application performance and operational health, and also being able to react quickly to operational changes.

What AWS service orchestrates and automates data-driven workflows?

AWS Glue is a service that orchestrates and automates data-driven workflows.

What AWS service can supplement an application’s logging, by storing, analyzing, and visualizing application data?

Amazon Elasticsearch Service can store, analyze, and visualize application data, supplementing an application’s logging capabilities.

How to encrypt the application log data stored in CloudWatch Logs?

AWS Key Management Service (KMS) can be used to encrypt the application log data stored in CloudWatch Logs.

What does it mean to transform log data in the context of AWS Kinesis?

Transforming log data in the context of Kinesis means to convert the data into a format that’s compatible with the destination.

What is the purpose of AWS Glue in the context of logging application data?

AWS Glue can discover new data and store associated metadata (e.g., table definition and schema) in the AWS Glue Data Catalog. Once cataloged, the data is immediately searchable, queryable, and available for ETL operations.