Loggformat

Loggformat refers to the structure used to record events in a log. It specifies how each log entry is encoded, including which fields are present, how they are separated, and how data types are represented. The chosen format affects readability for humans, ease of automated parsing, and storage efficiency.

Common components include a timestamp, a severity level (INFO, WARN, ERROR), a source or logger name, a message, and optional context such as a thread id, correlation id, or stack trace. Formats range from plain text to structured forms like JSON or key-value pairs. Structured formats such as JSON Lines are favored for machine parsing and analytics, while plain-text formats can aid quick manual review.

Standard practices vary. Syslog formats defined by RFC 5424 or RFC 3164 are widely used in network devices and servers. Web server logs may use the Common Log Format or other schemas. In software, loggformat is usually configured via a formatter or layout in the logging framework, or by a JSON serializer that writes structured entries. Some systems employ log shippers or agents that reformat logs as they are collected for centralized analysis.

Best practices for loggformat include using a structured format to support analysis, ensuring consistent field names across components, including precise timestamps in ISO 8601 with time zones, and avoiding sensitive data. Clear documentation and standardization facilitate log aggregation, correlation, and efficient troubleshooting.