Log Files are computer-generated data files used by software and operating systems to track information on events such as transactions, errors, and penetrations that have occurred. This event can be usage patterns, activities, or operations in an application, server, or operating system. It documents the event details, metadata, date, and time in a structured, semi-structured, or unstructured format.
Log data can be recorded in different formats as their sources on the production servers are hosted on different systems. Some of these sources can include a server access log, proxy server log, browser log, or any other data source generated by users coming from a web server.
In general, most applications use .log as an extension when generating a log file. It can contain day to day activity of a computer or the duration for which the application runs. Thus, we can diagnose the system or application in case we encounter any problems that need to be fixed quickly. This is required in large and complex applications where many events are generated in a short amount of time. These events are saved in the log file and can be identified by a name or unique ID, like a universally unique identifier (UUID). These log files are aggregated and used for analysis, debugging, and getting needed information about the system.
Common Information on Logs Format
Even though the sources of logs can be in different formats, some of this common information in the logs consists of the items
- Timestamp→ Exact time at which the event took place
- User information —> information about the user
- Event Details —> Gives information about the events that occurred.
Sources of Logs
Log files have many sources. Some common ones are given below.
- Applications and Software programs
- Mobile Applications
- Network Switches and Devices
- IoT Devices
- Cloud-based containers
- NoSQL and NoSQL Databases
- Firewalls
- REST API endpoints
- Servers and Data Centers
Uses of Logs files
Every organization that has a computing device has a certain volume of logs. These logs provide valuable insights into the diverse personnel in an organization. Some of these personnel are given below who use the information given in the log file for the organization.
- Software Developer/Data Engineer/ Data Scientist
- Information Technology Analyst
- IT Operation team
- Monitors the IT infrastructure
- Manages the workload and maintains outages to avoid any outages
- Reduces the risk and cost associated with the business
- Development Security Operations team
- Identifies any security issues before deployment
- Security Operation team
- DevOps/Site Reliability Engineering(SRE)
- Maintains and manages CI/CD
- Fixes any issues related to critical applications
- Applications performance improvement in the cluster
- Database Administrators
- Cybersecurity team
- Identifies and discovers information on any attack happening in real time
- Monitors any unusual and questionable activity
- Monitors any incoming traffic to the organization
Categories of Log Format
There is not a single default standard for the log format, as the different systems can implement the format in different ways. There are mainly four categories of Logs.
- Access Log file (Transfer)
This file stores data about all incoming requests, and information about the client, and records all requests that are processed by the web server.
- Error Log file
This file contains a list of all internal errors that occur when there is a connection problem between the client and server. Whenever a client requests a web page from a server and an error occurs, it is recorded in an error log file.
- Agent Log File
This log file contains data and meta-data related to the client browser and browser version.
- Referrer Log File
This file contains information about links and redirects visitor information to the site.