Log monitoring and processing

monitor.clj

(ns monitor
  (:gen-class)
  (:import (java.io RandomAccessFile)))

(def sleep-interval 2000)

(defn extract-ip-address [message]
  (if (not (nil? message))
    (let [pattern "(\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}) ([0-9a-f]+\\.[0-9a-f]+\\.[0-9a-f]+) via (\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3})"
          message-seq  (first (re-seq (re-pattern pattern) message))
          message-info (zipmap [:everything :to :mac :via] message-seq)] (get-in message-info [:to]))))

(defn analyze-line [line]
  (if (not (nil? line))
      (let [pattern "(^\\w+ \\d+ \\d\\d:\\d\\d:\\d\\d) [\\w]+ ([\\w]+)\\[\\d+\\]: ([\\w\\W]+)"
            log-line-seq  (first (re-seq (re-pattern pattern) line))] (zipmap [:everything :time :action :message] log-line-seq))))

(defn filter-ACK [message]
  (let [pattern "^Sending ACK to .*"
        message-seq  (first (re-seq (re-pattern pattern) message))] message-seq))

(defn process-log-entry
  "Extract information from the log file line."
  [line]
  (if-let [data (-> line
                    analyze-line
                    :message
                    filter-ACK
                    extract-ip-address)]
    (do (println (str "queue: " data)))))

(defn read-log
  "Loop through the log-file, process each entry, wait at the end. Start over when log is rotated"
  [^RandomAccessFile log-file]
  (let [line (.readLine log-file)]
    (if line
      (process-log-entry line)))
  (let [pointer (.getFilePointer log-file)
        length (.length log-file)]
    (cond (= pointer length) (do (Thread/sleep sleep-interval))
          (> pointer length) (do (.seek log-file 0))))
  (recur log-file))

(defn -main
  "Called from the :main entry in the Leiningen file."
  [& args]
  (println "main run")
  (future (read-log (RandomAccessFile. "/var/log/messages" "r"))))

project.clj

(defproject monitor "0.1.0-SNAPSHOT"
  :description "monitor a log file and process specific entries"
  :dependencies [[org.clojure/clojure "1.5.1"]]
  :main ^:skip-aot monitor.core
  :target-path "target/%s"
  :profiles {:uberjar {:aot :all}})

;; initial skeleton from 
;; Clojure Recipes
;; By: Julian Gamble
;; Publisher: Addison-Wesley Professional
;; Chapter 24. Detecting Errors with a Log Monitoring Application