kaappi-log — Structured Logging¶

thottam install kaappi-log

Pure Scheme — no dependencies.

Quick start¶

(import (kaappi log))

(log-info "server started" '("port" . 8080))
;=> 1719100000 [INFO] server started port=8080

(log-error "failed" '("code" . 500) '("path" . "/api"))
;=> 1719100000 [ERROR] failed code=500 path=/api

API¶

Logging¶

(log-debug msg field ...)
(log-info msg field ...)
(log-warn msg field ...)
(log-error msg field ...)
(log-fatal msg field ...)

Fields are pairs: '("key" . value)

Configuration¶

(log-set-level! LOG-WARN)                ; filter below WARN
(log-set-port! (current-output-port))    ; output destination
(log-set-format! 'json)                  ; JSON output
(log-set-format! 'text)                  ; text output (default)

Context fields¶

(log-with-fields '(("req_id" . "abc"))
  (lambda ()
    (log-info "handling request")))       ; includes req_id=abc

Output formats¶

Text (default):

1719100000 [INFO] request method=GET path=/api status=200

JSON:

{"time":"1719100000","level":"INFO","msg":"request","method":"GET","status":200}

Levels¶

LOG-DEBUG (0) < LOG-INFO (1) < LOG-WARN (2) < LOG-ERROR (3) < LOG-FATAL (4)