What are log files?

Log files are software-generated files containing information about the operations, activities, and usage patterns of an application, server, or IT system. They include a historical record of all processes, events, and messages along with additional descriptive data, such as timestamps, to contextualize this information. Timestamps show you what happened inside the system and when it happened. So, if something should go wrong with your systems, you have a detailed record of every action before the incident.

Why are log files important?

A log file provides a detailed and easily accessible record of system information that would otherwise be difficult to collate. It provides insight into the performance and compliance of your applications and systems. Log files are crucial for cloud applications because of their dynamic and distributed features.

Cloud-centered applications often have a service-oriented architecture. They are made of several independent software components, called microservices, that constantly communicate with each other for normal system functioning. It can be impossible to troubleshoot issues without access to these communication logs.

Some benefits of log files include the following:

  • You can gain meaningful insight into the overall well-being and functionality of your system
  • You can obtain an incident timeline for faster troubleshooting
  • You can identify security bugs and minimize security risks
  • You can optimize application performance over time

What are the types of log files?

The following are some common types of log files.

Event logs

An event log is a high-level log that records system activity data to provide an audit trail for troubleshooting issues. Event logs are essential to understand the behavior of complex systems, particularly in the case of applications with little user interaction. For example, in networks, event logs record network traffic, access, and usage.

System logs

A system log records operating system events, such as system changes, startup messages, errors, warnings, and unexpected shutdowns.

Access logs

An access log records the list of all requests for individual files that people or applications request from a system. It includes information about user authentication, who requested a particular system file, when they asked for it, and other associated information.

Server logs

A server log is a log file that a server automatically creates and maintains. It contains a list of activities that the server performs, such as the number of page requests, client IP addresses, types of requests, and so on.

Change logs

A change log is a file that contains a chronological record of changes made to the software. For example, it might log changes between different versions of an application or log configuration changes to a system.

Other types of logs

Depending on the use case, there are other types of log files, such as the following:

  • Availability logs that track system performance and availability
  • Resources logs that deliver information on connectivity issues
  • Threat logs that contain information regarding suspicious network profiles

What are log files used for?

Application and infrastructure operators use log files to troubleshoot problems, while business stakeholders derive insights from data embedded in log messages. The following are some example use cases.

Identify and troubleshoot errors

Event logs play a critical role in application and server monitoring. A monitoring software can send automatic alerts if it detects unexpected occurrences in the log file. Application development teams then use the records provided to debug and improve systems.

Improve operations

As applications and systems grow in complexity, the difficulty in managing them also increases. A system log makes it easier for IT teams to identify trends and optimize infrastructure. System engineers also use log files to identify potential issues and prevent incidents.

Enhance efficiency

Unexpected server overloads negatively impact performance and user experience. System log files help track resource usage and improve resource allocation. As a result, you can make better decisions on when to scale resources up or down. For example, you might discover that specific data queries are slowing down the system and allocate memory-intensive resources to them.

Understand user behavior

You can use log files with real-time user monitoring systems to better understand your users’ journey. By monitoring endpoints and UI workflows, you get an outside-in view of how users experience your application. These insights further improve customer satisfaction and might even support the launching of new products and services. For example, you might discover that file downloads are slowing down your application and choose to showcase the content as an in-application video instead.

Strengthen security

Log data analysis helps your cybersecurity team rapidly respond to unusual application events and reduce the risk of unauthorized access by third parties. The log data that correlates a system or network event with a user’s activity gives insights into standard user behavior. As a result, you can set alerts for unusual activity outside the observed typical pattern to ensure that compliance and security are fully maintained. For example, multiple unsuccessful login attempts could launch an alert to the security team.

What are log file management challenges?

While log files are critical for efficient IT infrastructure maintenance, you can experience management challenges because of their unique features.


Since modern IT systems record every activity, the number and size of log files quickly increases. Without proper procedures in place, you could end up with an overwhelming volume of logs that require manual analysis to be practically useful.

Format variation

Different systems generate log file data in various formats, such as structured, semistructured, or unstructured. However, logs need to be parsed or analyzed line by line so that developers and administrators can accurately use them. The absence of a logging standard makes parsing more complex and time-consuming.

Processing speed

A large amount of logging information and their parsing requirements can increase log management time. Inefficient log management systems prevent organizations from taking action in real time due to slow log-processing speeds.

How can Amazon support your log file management requirements?

Amazon CloudWatch is a monitoring and observability service that provides data and actionable insights to monitor your applications, respond to system-wide performance changes, and optimize resource utilization. CloudWatch collects monitoring and operational data in the form of logs, metrics, and events. You get a unified view of operational health and gain complete visibility of your AWS resources, applications, and services running on both AWS and on premises.

For example, you can use CloudWatch to do the following:

  • Integrate log files from over 70 AWS services, such as Amazon Elastic Compute Cloud (Amazon EC2), Amazon DynamoDB, Amazon Simple Storage Service (Amazon S3), Amazon Elastic Container Service (Amazon ECS), Amazon Elastic Kubernetes Service (Amazon EKS), and AWS Lambda
  • Automatically publish detailed 1-minute metrics and custom metrics for deep log analysis
  • Set alarms and automate actions based on predefined thresholds
  • Explore, analyze, and visualize logs to troubleshoot operational problems with ease

Get started with log management on AWS by creating a free account today.

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