ring middleware that mimics rails server log output.

1-output.txt

2013-Apr-11 01:57:00 INFO [hello-world.logger] - Started GET "/" for 127.0.0.1
2013-Apr-11 01:57:00 INFO [hello-world.logger] - Completed 200 OK in 1ms

2013-Apr-11 01:57:00 INFO [hello-world.logger] - Started GET "/brainsketch.gif" for 127.0.0.1
2013-Apr-11 01:57:00 INFO [hello-world.logger] - Completed 304 Not Modified in 4ms

2-rails-logger.clj

(ns hello-world.logger
 (:require [taoensso.timbre :refer [trace info debug warn error spy))

;; dependency: [com.taoensso/timbre "1.5.2"]

;; simple lookup table

(defn code->name 
  "Lookup table that maps http codes to a descriptive name."
  [code]
  (case code
    200 "OK"
    304 "Not Modified"
    404 "File Not Found"
    406 "Not Acceptable"
    ""))

;; a method that logs the 

(defn log-request-started 
  "Log message based on first request that the middleware sees."
  [request]
  (let [{:keys [request-method uri remote-addr]} request
        pp-method (upper-case request-method)
        pp-uri (str "\"" uri "\"")]
    (info "Started" pp-method pp-uri "for" remote-addr)))

(defn log-response-completed 
  "Log message based on the last response that middleware sees and an initial nanoTime start."
  [response start]
  (let [status-code (:status response)
        status-name (code->name status-code)
        duration (distance-ns->ms start (System/nanoTime))
        pp-duration (str duration "ms")]
    (info "Completed" status-code status-name "in" pp-duration)))

;; the actual middleware that incorporates the above

(defn wrap-railsy-logger 
  "Middleware that mimics Rails' dev server log output."
  [handler]
  (fn [request]
    (log-request-started request)
    (let [start (System/nanoTime)
          response (handler request)]
      (log-response-completed response start)
      response)))