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[com.taoensso/timbre "3.0.0-RC2"] ; Non-breaking upgrade - see CHANGELOG for details
[com.taoensso/timbre "2.7.1"] ; StableAppender authors: please see here about migrating Timbre 2.x appenders to 3.x's recommended style.
Logging with Java can be maddeningly, unnecessarily hard. Particularly if all you want is something simple that works out-the-box. Timbre brings functional, Clojure-y goodness to all your logging needs. No XML!
- Logs as Clojure values (v3+).
- Small, uncomplicated all-Clojure library.
- Super-simple map-based config: no arcane XML or properties files!
- Low overhead with dynamic logging level.
- No overhead with compile-time logging level. (v2.6+)
- Flexible fn-centric appender model with middleware.
- Sensible built-in appenders including simple email appender.
- Tunable rate limit and asynchronous logging support.
- Robust namespace filtering.
- tools.logging support (optional, useful when integrating with legacy logging systems).
- Dead-simple, logging-level-aware logging profiler.
Add the necessary dependency to your Leiningen project.clj and use the supplied ns-import helper:
[com.taoensso/timbre "3.0.0-RC2"] ; project.clj
(ns my-app (:require [taoensso.timbre :as timbre])) ; Your ns
(timbre/refer-timbre) ; Provides useful Timbre aliases in this nsThe refer-timbre call is a convenience fn that executes:
(require '[taoensso.timbre :as timbre
:refer (log trace debug info warn error fatal report
logf tracef debugf infof warnf errorf fatalf reportf
spy logged-future with-log-level)])
(require '[taoensso.timbre.utils :refer (sometimes)])
(require '[taoensso.timbre.profiling :as profiling :refer (pspy profile defnp)])By default, Timbre gives you basic print output to *out*/*err* at a debug logging level:
(info "This will print") => nil
%> 2012-May-28 17:26:11:444 +0700 localhost INFO [my-app] - This will print
(spy :info (* 5 4 3 2 1)) => 120
%> 2012-May-28 17:26:14:138 +0700 localhost INFO [my-app] - (* 5 4 3 2 1) 120
(trace "This won't print due to insufficient logging level") => nilFirst-argument exceptions generate a nicely cleaned-up stack trace using io.aviso.exception:
(info (Exception. "Oh noes") "arg1" "arg2")
%> 2012-May-28 17:35:16:132 +0700 localhost INFO [my-app] - arg1 arg2
java.lang.Exception: Oh noes
NO_SOURCE_FILE:1 my-app/eval6409
Compiler.java:6511 clojure.lang.Compiler.eval
<...>This is the biggest win over Java logging utilities IMO. Here's timbre/example-config (also Timbre's default config):
(def example-config
"APPENDERS
An appender is a map with keys:
:doc ; (Optional) string.
:min-level ; (Optional) keyword, or nil (no minimum level).
:enabled? ; (Optional).
:async? ; (Optional) dispatch using agent (good for slow appenders).
:rate-limit ; (Optional) [ncalls-limit window-ms].
:fmt-output-opts ; (Optional) extra opts passed to `fmt-output-fn`.
:fn ; (fn [appender-args-map]), with keys described below.
An appender's fn takes a single map with keys:
:level ; Keyword.
:error? ; Is level an 'error' level?.
:throwable ; java.lang.Throwable.
:args ; Raw logging macro args (as given to `info`, etc.).
:message ; Stringified logging macro args, or nil.
:output ; Output of `fmt-output-fn`, used by built-in appenders
; as final, formatted appender output. Appenders may (but
; are not obligated to) use this as their output.
:ap-config ; Contents of config's :shared-appender-config key.
:profile-stats ; From `profile` macro.
:instant ; java.util.Date.
:timestamp ; String generated from :timestamp-pattern, :timestamp-locale.
:hostname ; String.
:ns ; String.
;; Waiting on http://dev.clojure.org/jira/browse/CLJ-865:
:file ; String.
:line ; Integer.
MIDDLEWARE
Middleware are fns (applied right-to-left) that transform the map
dispatched to appender fns. If any middleware returns nil, no dispatching
will occur (i.e. the event will be filtered).
The `example-config` code contains further settings and details.
See also `set-config!`, `merge-config!`, `set-level!`."
{;;; Control log filtering by namespace patterns (e.g. ["my-app.*"]).
;;; Useful for turning off logging in noisy libraries, etc.
:ns-whitelist []
:ns-blacklist []
;; Fns (applied right-to-left) to transform/filter appender fn args.
;; Useful for obfuscating credentials, pattern filtering, etc.
:middleware []
;;; Control :timestamp format
:timestamp-pattern "yyyy-MMM-dd HH:mm:ss ZZ" ; SimpleDateFormat pattern
:timestamp-locale nil ; A Locale object, or nil
;; Output formatter used by built-in appenders. Custom appenders may (but are
;; not required to use) its output (:output). Extra per-appender opts can be
;; supplied as an optional second (map) arg.
:fmt-output-fn
(fn [{:keys [level throwable message timestamp hostname ns]}
;; Any extra appender-specific opts:
& [{:keys [nofonts?] :as appender-fmt-output-opts}]]
;; <timestamp> <hostname> <LEVEL> [<ns>] - <message> <throwable>
(format "%s %s %s [%s] - %s%s"
timestamp hostname (-> level name str/upper-case) ns (or message "")
(or (stacktrace throwable "\n" (when nofonts? {})) "")))
:shared-appender-config {} ; Provided to all appenders via :ap-config key
:appenders
{:standard-out
{:doc "Prints to *out*/*err*. Enabled by default."
:min-level nil :enabled? true :async? false :rate-limit nil
:fn (fn [{:keys [error? output]}] ; Use any appender args
(binding [*out* (if error? *err* *out*)]
(str-println output)))}
:spit
{:doc "Spits to `(:spit-filename :shared-appender-config)` file."
:min-level nil :enabled? false :async? false :rate-limit nil
:fn (fn [{:keys [ap-config output]}] ; Use any appender args
(when-let [filename (:spit-filename ap-config)]ar
(try (spit filename output :append true)
(catch java.io.IOException _))))}}})A few things to note:
- Appenders are trivial to write & configure - they're just fns. It's Timbre's job to dispatch useful args to appenders when appropriate, it's their job to do something interesting with them.
- Being 'just fns', appenders have basically limitless potential: write to your database, send a message over the network, check some other state (e.g. environment config) before making a choice, etc.
The logging level may be set:
- At compile-time: (
TIMBRE_LOG_LEVELenvironment variable). - Via an atom:
(timbre/set-level! <level>). (Usual method). - Via dynamic thread-level binding:
(timbre/with-log-level <level> ...).
A compile-time level offers zero-overhead performance since it'll cause insufficient logging calls to disappear completely at compile-time. Usually you won't need/want to bother: Timbre offers very decent performance with runtime level checks (~15msecs/10k checks on my Macbook Air).
For common-case ease-of-use, all logging utils use a global atom for their config. This is configurable with timbre/set-config!, timbre/merge-config!. The lower-level log and logf macros also take an optional first-arg config map for greater flexibility (e.g. during testing).
Redis (Carmine) appender (v3+)
;; [com.taoensso/carmine "2.4.0"] ; Add to project.clj deps
;; (:require [taoensso.timbre.appenders (:carmine :as car-appender)]) ; Add to ns
(timbre/set-config! [:appenders :carmine] (postal-appenders/make-carmine-appender))This gives us a high-performance Redis appender:
- All raw logging args are preserved in serialized form (even Throwables!).
- Only the most recent instance of each unique entry is kept (hash fn used to determine uniqueness is configurable).
- Configurable number of entries to keep per logging level.
- Log is just a value: a vector of Clojure maps: query+manipulate with standard seq fns: group-by hostname, sort/filter by ns & severity, explore exception stacktraces, filter by raw arguments, etc. Datomic and
core.logicalso offer interesting opportunities here.
A simple query utility is provided: car-appender/query-entries.
Email (Postal) appender
;; [com.draines/postal "1.9.2"] ; Add to project.clj deps
;; (:require [taoensso.timbre.appenders (postal :as postal-appender)]) ; Add to ns
(timbre/set-config! [:appenders :postal]
(postal-appender/make-postal-appender
{:enabled? true
:rate-limit [1 60000] ; 1 msg / 60,000 msecs (1 min)
:async? true ; Don't block waiting for email to send
}
{:postal-config
^{:host "mail.isp.net" :user "jsmith" :pass "sekrat!!1"}
{:from "[email protected]" :to "[email protected]"}}))(timbre/set-config! [:appenders :spit :enabled?] true)
(timbre/set-config! [:shared-appender-config :spit-filename] "/path/my-file.log")A number of 3rd-party appenders are included out-the-box for: Android, IRC, sockets, MongoDB, and rotating files. These are all located in the taoensso.timbre.appenders.x namespaces - please see the relevant docstrings for details.
Thanks to their respective authors! Just give me a shout if you've got an appender you'd like to have added.
The usual recommendation for Clojure profiling is: use a good JVM profiler like YourKit, JProfiler, or VisualVM.
And these certainly do the job. But as with many Java tools, they can be a little hairy and often heavy-handed - especially when applied to Clojure. Timbre includes an alternative.
Wrap forms that you'd like to profile with the p macro and give them a name:
(defn my-fn
[]
(let [nums (vec (range 1000))]
(+ (p :fast-sleep (Thread/sleep 1) 10)
(p :slow-sleep (Thread/sleep 2) 32)
(p :add (reduce + nums))
(p :sub (reduce - nums))
(p :mult (reduce * nums))
(p :div (reduce / nums)))))
(my-fn) => 42The profile macro can now be used to log times for any wrapped forms:
(profile :info :Arithmetic (dotimes [n 100] (my-fn))) => "Done!"
%> 2012-Jul-03 20:46:17 +0700 localhost INFO [my-app] - Profiling my-app/Arithmetic
Name Calls Min Max MAD Mean Total% Total
my-app/slow-sleep 100 2ms 2ms 31μs 2ms 57 231ms
my-app/fast-sleep 100 1ms 1ms 27μs 1ms 29 118ms
my-app/add 100 44μs 2ms 46μs 100μs 2 10ms
my-app/sub 100 42μs 564μs 26μs 72μs 2 7ms
my-app/div 100 54μs 191μs 17μs 71μs 2 7ms
my-app/mult 100 31μs 165μs 11μs 44μs 1 4ms
Unaccounted 6 26ms
Total 100 405msYou can also use the defnp macro to conveniently wrap whole fns.
It's important to note that Timbre profiling is fully logging-level aware: if the level is insufficient, you won't pay for profiling. Likewise, normal namespace filtering applies. (Performance characteristics for both checks are inherited from Timbre itself).
And since p and profile always return their body's result regardless of whether profiling actually happens or not, it becomes feasible to use profiling more often as part of your normal workflow: just leave profiling code in production as you do for logging code.
A simple sampling profiler is also available: taoensso.timbre.profiling/sampling-profile.
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CDS, the Clojure Documentation Site, is a contributer-friendly community project aimed at producing top-notch, beginner-friendly Clojure tutorials and documentation. Awesome resource.
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ClojureWerkz is a growing collection of open-source, batteries-included Clojure libraries that emphasise modern targets, great documentation, and thorough testing. They've got a ton of great stuff, check 'em out!
Please use the project's GitHub issues page for project questions/comments/suggestions/whatever (pull requests welcome!). Am very open to ideas if you have any!
Otherwise reach me (Peter Taoussanis) at taoensso.com or on Twitter (@ptaoussanis). Cheers!
Copyright © 2012, 2013 Peter Taoussanis. Distributed under the Eclipse Public License, the same as Clojure.