LogFormate

Logformate are predefined specifications for recording events in log files or streams, enabling consistent storage, retrieval, and analysis. They can be human-readable text or machine-readable structures. Some formats are designed for simple access logs and are easy to generate, while others provide rich fielded data suitable for automated processing.

Common textual formats include the Common Log Format (CLF) and the Combined Log Format used by web servers to record HTTP requests; the W3C Extended Log File Format specifies fields via configuration. Network devices often rely on syslog formats, while modern applications increasingly emit structured data such as JSON or XML. Structured formats like JSON, GELF, CSV/TSV, LTSV and CEF enable explicit fields (timestamp, host, service, level, message, request details, status, duration), facilitating parsing, indexing, and search. Each format has trade-offs between readability, verbosity, and parsing complexity.

In practice, the choice of log format depends on tooling and workflow. Structured formats integrate well with log shippers (Fluentd, Logstash), centralized platforms (Elasticsearch, Splunk), and SIEM systems, enabling efficient filtering, correlation, and alerting. Legacy or highly-volatile environments may still rely on free-text formats, requiring custom parsers. Considerations include performance, storage, time zone handling, encoding, and interoperability across systems.