**[API docs][]** | **[CHANGELOG][]** | [other Clojure libs][] | [Twitter][] | [contact/contrib](#contact--contributing) | current [Break Version][]: ```clojure [com.taoensso/timbre "3.4.0"] ; Stable [com.taoensso/timbre "4.0.0-beta4"] ; BREAKING, please see CHANGELOG for details ``` # Timbre, a (sane) Clojure/Script logging & profiling library Java logging is a tragic comedy of crazy, unnecessary complexity that buys you _nothing_. It can be maddeningly, unnecessarily hard to get even the simplest logging working. We can do **so** much better with Clojure/Script. Timbre brings functional, Clojure-y goodness to all your logging needs. It's fast, deeply flexible, and easy to configure. **No XML**! ## What's in the box™? * Full **Clojure** + **ClojureScript** support (v4+) * No XML or properties files. **One config map**, and you're set * Deeply flexible **fn appender model** with **middleware** * **Fantastic performance** at any scale * Filter logging by levels and **namespace whitelist/blacklist patterns** * **Zero overhead** with **complete Clj+Cljs elision** for compile-time level/ns filters * Useful built-in appenders for **out-the-box** Clj+Cljs logging * Powerful, easy-to-configure per-appender **rate limits** and **async logging** * [Logs as Clojure values](#redis-carmine-appender-v3) (v3+) * [tools.logging](https://github.com/clojure/tools.logging) support (optional, useful when integrating with legacy logging systems) * Level and ns-filter aware **logging profiler** * Tiny, **simple**, cross-platform codebase ## 3rd-party tools, appenders, etc. * [log-config](https://github.com/palletops/log-config) by [Hugo Duncan](https://github.com/hugoduncan) - library to help manage Timbre logging config. * Other suggestions welcome! ## Getting started ### Dependencies Add the necessary dependency to your [Leiningen][] `project.clj` and use the supplied ns-import helper: ```clojure [com.taoensso/timbre "4.0.0-beta4"] ; Add to your project.clj :dependencies (ns my-app ; Your ns (:require [taoensso.timbre :as timbre :refer (log trace debug info warn error fatal report logf tracef debugf infof warnf errorf fatalf reportf spy)] ;; Clj only: [taoensso.timbre.profiling :as profiling :refer (pspy pspy* profile defnp p p*)])) ``` You can also use `timbre/refer-timbre` to setup these ns refers automatically (Clj only). ### Logging By default, Timbre gives you basic print stream or `js/console` (v4+) output at a `debug` log level: ```clojure (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 log level") => nil ``` First-argument exceptions generate a nicely cleaned-up stack trace using [io.aviso.exception](https://github.com/AvisoNovate/pretty) (Clj only): ```clojure (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 <...> ``` ### Configuration This is the biggest win over Java logging IMO. Here's `timbre/example-config` (also Timbre's default config): > The example below shows config for **Timbre v4**. See [here](https://github.com/ptaoussanis/timbre/tree/v3.4.0#configuration) for an example of **Timbre v3** config. ```clojure (def example-config "Example (+default) Timbre v4 config map. APPENDERS An appender is a map with keys: :min-level ; Level keyword, or nil (=> no minimum level) :enabled? ; :async? ; Dispatch using agent? Useful for slow appenders :rate-limit ; [[ncalls-limit window-ms] <...>], or nil :output-fn ; Optional override for inherited (fn [data]) -> string :fn ; (fn [data]) -> side effects, with keys described below An appender's fn takes a single data map with keys: :config ; Entire config map (this map, etc.) :appender-id ; Id of appender currently dispatching :appender ; Entire map of appender currently dispatching :instant ; Platform date (java.util.Date or js/Date) :level ; Keyword :error-level? ; Is level e/o #{:error :fatal}? :?ns-str ; String, or nil :?file ; String, or nil ; Waiting on CLJ-865 :?line ; Integer, or nil ; Waiting on CLJ-865 :?err_ ; Delay - first-arg platform error, or nil :vargs_ ; Delay - raw args vector :hostname_ ; Delay - string (clj only) :msg_ ; Delay - args string :timestamp_ ; Delay - string :output-fn ; (fn [data]) -> formatted output string :profile-stats ; From `profile` macro MIDDLEWARE Middleware are simple (fn [data]) -> ?data fns (applied left->right) that transform the data map dispatched to appender fns. If any middleware returns nil, NO dispatching will occur (i.e. the event will be filtered). The `example-config` source code contains further settings and details. See also `set-config!`, `merge-config!`, `set-level!`." {:level :debug ; e/o #{:trace :debug :info :warn :error :fatal :report} ;; Control log filtering by namespaces/patterns. Useful for turning off ;; logging in noisy libraries, etc.: :ns-whitelist [] #_["my-app.foo-ns"] :ns-blacklist [] #_["taoensso.*"] :middleware [] ; (fns [data]) -> ?data, applied left->right ;; Clj only: :timestamp-opts default-timestamp-opts ; {:pattern _ :locale _ :timezone _} :output-fn default-output-fn ; (fn [data]) -> string :appenders {:example-println-appender ; Appender id ;; Appender definition (just a map): {:enabled? true :async? false :min-level nil :rate-limit [[1 250] [10 5000]] ; 1/250ms, 10/5s :output-fn :inherit :fn ; Appender's fn (fn [data] (let [{:keys [output-fn]} data formatted-output-str (output-fn data)] (println formatted-output-str)))}}}) ``` 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 **log level** may be set: * At compile-time: (`TIMBRE_LEVEL` environment variable). * Statically using: `timbre/set-level!`/`timbre/merge-level!`. * Dynamically using: `timbre/with-level`. There are also variants of the logging utils that take explicit config args. ### Built-in appenders #### Redis ([Carmine](https://github.com/ptaoussanis/carmine)) appender (v3+) ```clojure ;; [com.taoensso/carmine "2.10.0"] ; Add to project.clj deps ;; (:require [taoensso.timbre.appenders (carmine :as car-appender)]) ; Add to ns (timbre/merge-config! {:appenders {:carmine (car-appender/make-appender)}}) ``` This gives us a high-performance Redis appender: * **All raw logging args are preserved** in serialized form (**even errors!**). * 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 log 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, stick into or query with **Datomic**, etc. A simple query utility is provided: `car-appender/query-entries`. #### Email ([Postal](https://github.com/drewr/postal)) appender ```clojure ;; [com.draines/postal "1.11.3"] ; Add to project.clj deps ;; (:require [taoensso.timbre.appenders (postal :as postal-appender)]) ; Add to ns (timbre/merge-config! {:appenders {:postal (postal-appender/make-appender {} {:postal-config ^{:host "mail.isp.net" :user "jsmith" :pass "sekrat!!1"} {:from "me@draines.com" :to "foo@example.com"}})}}) ``` #### File appender ```clojure (timbre/merge-config! {:appenders {:spit {:enabled? true :opts {:spit-finame "/path/my-file.log"}}}}) ``` #### Other included appenders A number of 3rd-party appenders are included out-the-box [here](https://github.com/ptaoussanis/timbre/tree/master/src/taoensso/timbre/appenders/3rd_party). **Please see the relevant docstring for details**. Thank you to the respective authors! Just give me a shout if you've got an appender you'd like to have added. ## Profiling (currently Clj only) The usual recommendation for Clojure profiling is: use a good **JVM profiler** like [YourKit](http://www.yourkit.com/), [JProfiler](http://www.ej-technologies.com/products/jprofiler/overview.html), or [VisualVM](http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/index.html). 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: ```clojure (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) => 42 ``` The `profile` macro can now be used to log times for any wrapped forms: ```clojure (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 405ms ``` You can also use the `defnp` macro to conveniently wrap whole fns. Timbre profiling is fully **log level & ns filter aware**: if the level is insufficient or ns filtered, you **won't pay for profiling**. And since `p` and `profile` **always return their body's result**, it becomes feasible to use profiling more often as part of your normal workflow: just *leave profiling code in production as you do logging code*. A simple sampling profiler is also included. ## This project supports the CDS and ![ClojureWerkz](https://raw.github.com/clojurewerkz/clojurewerkz.org/master/assets/images/logos/clojurewerkz_long_h_50.png) goals * [CDS][], the **Clojure Documentation Site**, is a **contributer-friendly** community project aimed at producing top-notch, **beginner-friendly** Clojure tutorials and documentation. Awesome resource. * [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! ## Contact & contributing `lein start-dev` to get a (headless) development repl that you can connect to with [Cider][] (Emacs) or your IDE. 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][]. Cheers! ## License Copyright © 2012-2015 Peter Taoussanis. Distributed under the [Eclipse Public License][], the same as Clojure. [API docs]: http://ptaoussanis.github.io/timbre/ [CHANGELOG]: https://github.com/ptaoussanis/timbre/releases [other Clojure libs]: https://www.taoensso.com/clojure [taoensso.com]: https://www.taoensso.com [Twitter]: https://twitter.com/ptaoussanis [issues page]: https://github.com/ptaoussanis/timbre/issues [commit history]: https://github.com/ptaoussanis/timbre/commits/master [Break Version]: https://github.com/ptaoussanis/encore/blob/master/BREAK-VERSIONING.md [Leiningen]: http://leiningen.org/ [Cider]: https://github.com/clojure-emacs/cider [CDS]: http://clojure-doc.org/ [ClojureWerkz]: http://clojurewerkz.org/ [Eclipse Public License]: https://raw2.github.com/ptaoussanis/timbre/master/LICENSE