Understanding Logging Levels

What Is a Logging Level?

A logging level, often referred to as a log level, is a way to categorize and prioritize log messages generated by a software application. Log levels help in managing and analyzing logs efficiently by assigning different levels to different types of messages based on their severity, significance, or purpose.

Different types of logging levels

The commonly used log levels include:

EMERGENCY

The most severe log level, indicates a system-wide crisis that requires immediate attention. At this level, the system is in an unusable state, and urgent intervention is needed to address the critical situation.

Examples: Server crashed, Database connection failed, Critical hardware failure detected, Network outage, File system corruption detected, etc.

ALERT

A condition that should be addressed immediately but does not necessarily indicate a system failure. Action must be taken immediately.

Examples: High CPU usage detected, Unavailability of payment processing, A sudden, unexpected surge in website traffic, etc.

CRITICAL

A critical condition that indicates a serious error or failure in the system. This log level is used for situations that require immediate attention due to the severity of the issue.

Examples: Server Disk Full, An essential external API is not responding, Database connection failed, Application component unavailable, unexpected exception, etc.

ERROR

Indicates an error that requires attention but does not necessarily result in system failure. This log level is used for situations where an error occurred, but the system can still function.

Examples: Database Query Error, User Input Validation Failure, External API Timeout, Different Runtime errors, File not found, etc.

WARNING

Indicates a potential issue or a condition that might lead to errors if not addressed. These are exceptional occurrences that are not errors but may require attention to prevent future problems.

Examples: Use of deprecated APIs, poor use of an API, Disk space running low, API Rate Limit Exceeded, Expiring SSL Certificate, etc.

NOTICE

Indicates normal but significant events that may be of interest for monitoring. This log level is used for messages that provide valuable information about the system's operation without indicating a problem or error

Examples: Scheduled Maintenance Start, New User Registration, API Key Rotation Completed, Cache Refreshed, Successful Database Backup, etc.

INFO

General information about the system's operation. This log level is used for messages that provide broad insights into the system's activities, helping to monitor its overall functionality.

Examples: User logs, SQL logs, File Upload Completed, Scheduled Task Execution, etc.

DEBUG

Detailed information, typically used for debugging purposes. This log level is used for messages that provide granular details about the system's internal processes, helping developers troubleshoot issues during development or testing.

Examples: Logging details about the execution of an SQL query, Logging details about the control flow within a complex algorithm, Logging detailed information about an HTTP request and its corresponding response, etc.