**[CHANGELOG]** | [API] | current [Break Version]: ```clojure [com.taoensso/timbre "4.8.0"] ; Please check CHANGELOG for details ``` > Please consider helping to [support my continued open-source Clojure/Script work]? > > Even small contributions can add up + make a big difference to help sustain my time writing, maintaining, and supporting Timbre and other Clojure/Script libraries. **Thank you!** > > \- Peter Taoussanis # Timbre ## A pure Clojure/Script logging library Java logging is a Kafkaesque mess of complexity that buys you _nothing_. It can be comically hard to get even the simplest logging working, and it just gets worse at scale. Timbre offers an **all Clojure/Script** alternative that's fast, deeply flexible, easy to configure, and that **works out the box**. No XML. Supports optional interop with [tools.logging](https://github.com/ptaoussanis/timbre/blob/master/src/taoensso/timbre/tools/logging.clj) and [log4j/logback/slf4j](https://github.com/fzakaria/slf4j-timbre). Happy hacking! ## Features * Full **Clojure** + **ClojureScript** support (v4+). * No XML or properties files. **A single, simple config map**, and you're set. * Simple, flexible **fn appender model** with **middleware**. * **Great performance** at any scale. * Filter logging by levels, **namespace whitelist/blacklist patterns**, and more. * **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 **rate limits** and **async logging**. * [Logs as Clojure values][] (v3+). * Small, simple, cross-platform codebase. ## 3rd-party tools, appenders, etc. Link | Description ------------------------ | ----------------------------------------------------- [@fzakaria/slf4j-timbre] | Route log4j/logback/sfl4j log output to Timbre [@palletops/log-config] | Library to help manage Timbre logging config Your link here? | **PR's welcome!** ## Getting started Add the necessary dependency to your project: ```clojure [com.taoensso/timbre "4.8.0"] ``` And setup your namespace imports: ```clojure (ns my-clj-ns ; Clojure namespace (:require [taoensso.timbre :as timbre :refer [log trace debug info warn error fatal report logf tracef debugf infof warnf errorf fatalf reportf spy get-env]])) (ns my-cljs-ns ; ; ClojureScript namespace (:require [taoensso.timbre :as timbre :refer-macros [log trace debug info warn error fatal report logf tracef debugf infof warnf errorf fatalf reportf spy get-env]])) ``` > You can also call `(timbre/refer-timbre)` to configure Clj ns referrals **automatically**. ### Logging By default, Timbre gives you basic `println` and `js/console` (v4+) output at a `:debug` log level: ```clojure (info "This will print") => nil %> 15-Jun-13 19:18:33 localhost INFO [my-app.core] - This will print (spy :info (* 5 4 3 2 1)) => 120 %> 15-Jun-13 19:19:13 localhost INFO [my-app.core] - (* 5 4 3 2 1) => 120 (defn my-mult [x y] (info "Lexical env:" (get-env)) (* x y)) => #'my-mult (my-mult 4 7) => 28 %> 15-Jun-13 19:21:53 localhost INFO [my-app.core] - Lexical env: {x 4, y 7} (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][] (Clj only): ```clojure (info (Exception. "Oh noes") "arg1" "arg2") %> 15-Jun-13 19:22:55 localhost INFO [my-app.core] - arg1 arg2 java.lang.Exception: On noes ``` Other utils include: `log-errors`, `log-and-rethrow-errors`, `logged-future`, and `handle-uncaught-jvm-exceptions!` (please see the [API] for details). #### Disabling stacktrace colors ANSI colors are enabled by default for stacktraces. To turn these off (e.g. for log files or emails), you can add the following entry to your top-level config **or** individual appender map/s: ```clojure :output-fn (partial timbre/default-output-fn {:stacktrace-fonts {}}) ``` And/or you can set the `TIMBRE_DEFAULT_STACKTRACE_FONTS` environment variable (supports edn). ### Data flow Timbre's inherently a very simple design, no magic. It's just Clojure data and functions: 1. Unfiltered logging calls generate a **data map**: `{:level _ :?ns-str _ ...}` 2. The resulting data map passes through any **middleware fns**, `(fn [data]) -> ?data` 3. The resulting data map is sent to all **appender fns**, `(fn [data]) -> ?effects` ### Configuration This is the biggest win over Java logging IMO. **All** of Timbre's behaviour is controlled through a single, simple Clojure map. > See `timbre/example-config` for Timbre's default config map ```clojure (def example-config "An example 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 (clj only) :rate-limit ; [[ncalls-limit window-ms] <...>], or nil :output-fn ; Optional override for inherited (fn [data]) -> string :timestamp-opts ; Optional override for inherited {:pattern _ :locale _ :timezone _} (clj only) :ns-whitelist ; Optional, stacks with active config's whitelist :ns-blacklist ; Optional, stacks with active config's blacklist :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 :?line ; Integer, or nil ; Waiting on CLJ-865 :?err ; First-arg platform error, or nil :vargs ; Vector of raw args :output_ ; Forceable - final formatted output string created ; by calling (output-fn ) :msg_ ; Forceable - args as a string :timestamp_ ; Forceable - string (clj only) :hostname_ ; Forceable - string (clj only) :output-fn ; (fn [data]) -> formatted output string ; (see `default-output-fn` for details) :context ; *context* value at log time (see `with-context`) **NB** - any keys not specifically documented here should be considered private / subject to change without notice. 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 dispatch 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 {;; The standard println appender: ;; :println (println-appender {:stream :auto}) :an-example-custom-println-appender ;; Inline 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 [data]) -> side effects (fn [data] (let [{:keys [output_]} data formatted-output-str (force output_)] (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. #### Log levels and ns filters 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`. The **ns filters** may be set: * At compile-time: (`TIMBRE_NS_WHITELIST`, `TIMBRE_NS_BLACKLIST` env vars). * Statically using: `timbre/set-config!`/`timbre/merge-config!`. * Dynamically using: `timbre/with-config`. There are also variants of the core logging macros that take an **explicit config arg**: ```clojure (timbre/log* <& args>) ; or (timbre/logf* <& args>) ``` Logging calls excluded by a compile-time option (e.g. during Cljs compilation) will be **entirely elided from your codebase**, e.g.: ```bash #!/bin/bash # edn values welcome: export TIMBRE_LEVEL=':warn' # Elide all lower logging calls export TIMBRE_NS_WHITELIST='["my-app.*"]' # Elide all other ns logging calls export TIMBRE_NS_BLACKLIST='["my-app.foo" "my-app.bar.*"]' lein cljsbuild once # Compile js with appropriate logging calls excluded lein uberjar # Compile jar '' ``` ### Built-in appenders #### Basic file appender ```clojure ;; (:require [taoensso.timbre.appenders.core :as appenders]) ; Add to ns (timbre/merge-config! {:appenders {:spit (appenders/spit-appender {:fname "/path/my-file.log"})}}) ;; (timbre/merge-config! {:appenders {:spit {:enabled? false}}} ; To disable ;; (timbre/merge-config! {:appenders {:spit nil}} ; To remove entirely ``` #### Redis ([Carmine]) appender (v3+) ```clojure ;; [com.taoensso/carmine ] ; Add to project.clj deps ;; (:require [taoensso.timbre.appenders (carmine :as car-appender)]) ; Add to ns (timbre/merge-config! {:appenders {:carmine (car-appender/carmine-appender)}}) ``` This gives us a high-performance Redis appender: * **All raw logging args are preserved** in serialized form (even errors). * Configurable number of entries to keep per log level. * Only the most recent instance of each **unique entry** is kept. * Resulting **log is just a Clojure value**: a vector of log entries (maps). Clojure has a rich selection of built-in and 3rd party tools for querying values like this. See also `car-appender/query-entries`. #### Email ([Postal]) appender ```clojure ;; [com.draines/postal ] ; Add to project.clj deps ;; (:require [taoensso.timbre.appenders (postal :as postal-appender)]) ; Add to ns (timbre/merge-config! {:appenders {:postal (postal-appender/postal-appender ^{:host "mail.isp.net" :user "jsmith" :pass "sekrat!!1"} {:from "me@draines.com" :to "foo@example.com"})}}) ``` #### 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**. Thanks goes to the respective authors! Just give me a shout if you've got an appender you'd like to have added. ## Profiling As of v4.6.0, Timbre's profiling features have been enhanced and exported to a dedicated profiling library called [Tufte]. Timbre's old profiling features **will be kept for backwards compatibility** throughout v4.x, but future development will be focused exclusively on Tufte. Tufte has out-the-box support for integration with Timbre, and [migration](https://github.com/ptaoussanis/tufte#how-does-tufte-compare-to-the-profiling-in-timbre) is usually simple. Sorry for the inconvenience! ## This project supports the ![ClojureWerkz-logo] goals [ClojureWerkz] is a growing collection of open-source, **batteries-included Clojure libraries** that emphasise modern targets, great documentation, and thorough testing. ## Contacting me / contributions Please use the project's [GitHub issues page] for all questions, ideas, etc. **Pull requests welcome**. See the project's [GitHub contributors page] for a list of contributors. Otherwise, you can reach me at [Taoensso.com]. Happy hacking! \- [Peter Taoussanis] ## License Distributed under the [EPL v1.0] \(same as Clojure). Copyright © 2015-2016 [Peter Taoussanis]. [Taoensso.com]: https://www.taoensso.com [Peter Taoussanis]: https://www.taoensso.com [@ptaoussanis]: https://www.taoensso.com [More by @ptaoussanis]: https://www.taoensso.com [Break Version]: https://github.com/ptaoussanis/encore/blob/master/BREAK-VERSIONING.md [support my continued open-source Clojure/Script work]: http://taoensso.com/clojure/backers [CHANGELOG]: https://github.com/ptaoussanis/timbre/releases [API]: http://ptaoussanis.github.io/timbre/ [GitHub issues page]: https://github.com/ptaoussanis/timbre/issues [GitHub contributors page]: https://github.com/ptaoussanis/timbre/graphs/contributors [EPL v1.0]: https://raw.githubusercontent.com/ptaoussanis/timbre/master/LICENSE [Hero]: https://raw.githubusercontent.com/ptaoussanis/timbre/master/hero.png "Title" [logging profiler]: #profiling [Logs as Clojure values]: #redis-carmine-appender-v3 [@palletops/log-config]: https://github.com/palletops/log-config [@fzakaria/slf4j-timbre]: https://github.com/fzakaria/slf4j-timbre [io.aviso.exception]: https://github.com/AvisoNovate/pretty [Carmine]: https://github.com/ptaoussanis/carmine [Tufte]: https://github.com/ptaoussanis/tufte [Postal]: https://github.com/drewr/postal [ClojureWerkz-logo]: https://raw.github.com/clojurewerkz/clojurewerkz.org/master/assets/images/logos/clojurewerkz_long_h_50.png [ClojureWerkz]: http://clojurewerkz.org/