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CHANGELOG | API | current Break Version:
[com.taoensso/timbre "4.2.1"] ; Stable
Timbre
A pure Clojure/Script logging library
Java logging is a mess of complexity that buys you nothing. It can be comically hard to get even the simplest logging working, and it's no better at scale.
Timbre offers an all Clojure/Script alternative that works out the box. It's fast, deeply flexible, and easy to configure. No XML!
Features
- Full Clojure + ClojureScript support (v4+)
- No XML or properties files. A single, simple config map, and you're set
- Deeply flexible fn appender model with middleware
- Great 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 (v3+)
- tools.logging support (optional, useful when integrating with legacy logging systems)
- Level and ns-filter aware logging profiler
- Small, simple, cross-platform codebase
3rd-party tools, appenders, etc.
| Link | Description |
|---|---|
| @palletops/log-config | Library to help manage Timbre logging config |
| @fzakaria/slf4j-timbre | Route log4j/logback/sfl4j log output to Timbre |
| Your link here? | PR's welcome! |
Getting started
Add the necessary dependency to your project:
[com.taoensso/timbre "4.2.1"]
And setup your namespace imports:
(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 log-env)]
[taoensso.timbre.profiling :as profiling
:refer (pspy pspy* profile defnp p p*)]))
(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 log-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:
(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):
(info (Exception. "Oh noes") "arg1" "arg2")
%> 15-Jun-13 19:22:55 localhost INFO [my-app.core] - arg1 arg2
java.lang.Exception: On noes
<Stacktrace>
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:
:output-fn (partial timbre/default-output-fn {:stacktrace-fonts {}})
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 for an example of Timbre v3 config.
(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
; (see `default-output-fn` for details)
:context ; *context* value at log time (see `with-context`)
: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.
Log levels and ns filters
The log level may be set:
- At compile-time: (
TIMBRE_LEVELenvironment 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_BLACKLISTenv 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:
(timbre/log* <config-map> <level> <& args>) ; or
(timbre/logf* <config-map> <level> <& args>)
Logging calls excluded by a compile-time option (e.g. during Cljs compilation) will be entirely elided from your codebase, e.g.:
#!/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
Redis (Carmine) appender (v3+)
;; [com.taoensso/carmine <latest-version>] ; 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!)
- 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) appender
;; [com.draines/postal <latest-version>] ; 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"})}})
File appender
;; (:require [taoensso.timbre.appenders.core :as appenders]) ; Add to ns
(timbre/merge-config!
{:appenders {:spit (appenders/spit-appender {:fname "/path/my-file.log"})}})
Other included appenders
A number of 3rd-party appenders are included out-the-box here. 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], [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) => 42
The 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 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 ![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!
License
Distributed under the EPL v1.0 (same as Clojure).
Copyright © 2015-2016 Peter Taoussanis.
[YourKit]: http://www.yourkit.com/) [JProfiler]: http://www.ej-technologies.com/products/jprofiler/overview.html [VisualVM]: http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/index.html [ClojureWerkz-logo]: https://raw.github.com/clojurewerkz/clojurewerkz.org/master/assets/images/logos/clojurewerkz_long_h_50.png [ClojureWerkz]: http://clojurewerkz.org/
