Logs

Although logs have evolved, what constitutes a log is quite broad. Also known as log files, a log is a record of events written to output. Traditionally, logs would be written to a file on disk, searching through as needed. A more recent practice is to emit logs to remote services using the network. This provides long-term storage for the data in a location and improves searchability and aggregation.

Anatomy of a log

Many applications define their formats for what constitutes a log. There are several existing standard formats. An example includes the Common Log Format often used by web servers. It's challenging to identify commonalities across formats, but at the very least, a log should consist of the following:

• A timestamp recording the time of the event
• The message or payload representing the event

This message can take many forms and include various application-specific information. In the case of structured logging, the log is formatted as a...