parser: Parse and segment structured messages

The filters and default macros of AxoSyslog work well on the headers and metainformation of the log messages, but are rather limited when processing the content of the messages. Parsers can segment the content of the messages into name-value pairs, and these names can be used as user-defined macros. Subsequent filtering or other type of processing of the message can use these custom macros to refer to parts of the message. Parsers are global objects most often used together with filters and rewrite rules.

The AxoSyslog application provides the following possibilities to parse the messages, or parts of the messages, as shown on the following list. There are several built-in parsers for application-specific logs.

Note that by default, AxoSyslog parses every message as a syslog message. To disable parsing the message as a syslog message, use the flags(no-parse) option of the source. To explicitly parse a message as a syslog message, use the syslog parser. For details, see Parsing syslog messages.

Last modified January 26, 2024: [parsers] Minor clarification (ca85648)