Understanding Log Levels

Logging is a crucial part of application monitoring and troubleshooting. But not all logs are created equal. Different log levels help categorize the importance and urgency of log messages, making it easier to filter and analyze data efficiently. Various standards define these levels, but after careful consideration, we chose RFC5424 as the foundation for our log management system.

Common Log Level Standards

Although RFC5424 probably is the most commonly used, several log level standards exist. Each with its own approach to structuring logs:

• Syslog (RFC5424) – A widely adopted standard that defines eight log levels, ensuring consistency across different systems and applications.

• Apache Log Levels – Used mainly in web server logging, categorizing logs into severity levels like debug, info, notice, warn, error, crit, alert, and emerg.

• Java Logging (JUL, Log4j, SLF4J) – Common in Java applications, using levels such as finest, finer, fine, config, info, warning, and severe.

• Python Logging – Includes levels like debug, info, warning, error, and critical.

Why We Chose RFC5424

RFC5424, the latest Syslog protocol specification, provides a structured and standardized approach to log levels. Its eight well-defined levels ensure clear categorization, making it easier to prioritize and process logs effectively. Additionally, RFC5424’s widespread adoption across different platforms and programming languages ensures better compatibility and integration.

The 8 Log Levels in RFC5424

RFC5424 defines the following log levels, each assigned a numerical severity value:

1. Emergency (0) – The system is unusable. Example: "Database corruption detected! System shutting down."

2. Alert (1) – Immediate action is required. Example: "Security breach detected! Notify admin immediately."

3. Critical (2) – A critical condition that may cause failure. Example: "Disk space critically low. System performance affected."

4. Error (3) – General errors that should be addressed. Example: "Failed to connect to API endpoint. Retrying..."

5. Warning (4) – Potential issues that don’t immediately affect performance. Example: "High memory usage detected."

6. Notice (5) – Normal but significant events. Example: "New user account created."

7. Informational (6) – General operational messages. Example: "Service started successfully."

8. Debug (7) – Detailed information for debugging. Example: "Processing request ID: 12345."

When to Use Each Log Level

Choosing the right log level helps maintain a clean and useful logging system. Here’s when you should use each level:

• Emergency (0) & Alert (1) – Use these only for catastrophic failures that require immediate attention, such as a complete system crash or security breach.

• Critical (2) & Error (3) – Log these for application failures, service outages, or critical bugs that affect normal operation.

• Warning (4) – Use for situations that aren’t causing failures yet but could lead to issues if left unresolved (e.g., high CPU usage, nearing disk capacity limits).

• Notice (5) & Informational (6) – Ideal for tracking key system events that don’t indicate problems but are useful for monitoring, like user logins or system startups.

• Debug (7) – Reserved for development and troubleshooting, providing detailed insights into application behavior and workflow.

Stay tuned

By adopting RFC5424, we ensure that our log management system follows a structured, universally recognized standard. This helps users efficiently categorize, search, and analyze logs, leading to better application monitoring and troubleshooting.

Stay tuned as we continue to refine our logging infrastructure for even greater reliability and ease of use! 🚀