Clojure Q&A - Recent questions and answers in tools.logging

Answered: Using namespace as log originating class for JUL

Sun, 05 Nov 2023 14:59:43 +0000

I suspect something is wrong in your setup. I'm using Logback over SLF4J in my projects and the logger key in the format always outputs the right namespace. The JUL implementation of the c.t.l logger isn't that different.

Just to be absolutely certain, I created a very bare-bones project with just a single namespace:

(ns app.core
  (:require [clojure.tools.logging :as log]
            [clojure.tools.logging.impl :as log-impl]))

(defn -main []
  (System/setProperty "java.util.logging.SimpleFormatter.format"
                      "[%1$tF %1$tT] [%4$-7s] [%3$s] %5$s %n")
  (binding [log/*logger-factory* (log-impl/jul-factory)]
    (log/info "Hello")))

It depends only on org.clojure/tools.logging {:mvn/version "1.2.4"}.
When it's run with clj -M -m app.core, I see this in the console:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[2023-11-05 16:57:41] [INFO   ] [app.core] Hello

As you can see, the readable namespace name is there.

(That was just for a quick test and you shouldn't use c.t.l.impl like that of course. And probably set the format via an actual property or a properties file.)

Answered: Provide slf4j 2.0 factory for tools.logging?

Tue, 15 Nov 2022 18:23:33 +0000

I've created a jira to track this at https://clojure.atlassian.net/browse/TLOG-28. If you're interested in providing a patch, you can follow the process to become a contributor (see https://clojure.org/dev/dev#_becoming_a_contributor ).

Answered: `condp = level#` in tools.logging

Mon, 09 Aug 2021 13:23:28 +0000

Logged as https://clojure.atlassian.net/browse/TLOG-26

Answered: Can I suppress low-level logs with tools.logging?

Sat, 04 Jan 2020 14:12:43 +0000

If you simply want to disable all logging that happens in a certain call, you can tell tools.logging to use the provided disabled-logger-factory.

(require '[clojure.tools.logging :as log]
         '[clojure.tools.logging.impl :as log-impl])

(binding [log/*logger-factory* log-impl/disabled-logger-factory]
  (call-to-noisy-lib))

If you are looking to drop messages based on the originating namespace,
you can create your own LoggerFactory.

(def default-factory (log-impl/find-factory))

(def custom-factory
  (reify log-impl/LoggerFactory
    (name [_factory]
      "some.arbitrary.name.for.this.factory")
    (get-logger [factory logger-ns]
      (if (= "namespace.you.want.to.silence" (str logger-ns))
        log-impl/disabled-logger
        (log-impl/get-logger default-factory logger-ns)))))

(binding [log/*logger-factory* custom-factory]
  (call-to-noisy-lib))

If you addtionally want to filter based on the level of the message,
you'll need to implement a custom logger as well.

(defn logger-with-levels [wrapped-logger allowed-levels]
  (reify log-impl/logger
    (enabled? [logger level]
      (when (contains? allowed-levels level)
        (log-impl/enabled? wrapped-logger level)))
    (write! [logger level throwable message]
      (when (contains? allowed-levels level)
        (log-impl/write! wrapped-logger level throwable message)))))

(def custom-factory
  (reify log-impl/LoggerFactory
    (name [_factory]
      "some.arbitrary.name.for.this.factory")
    (get-logger [factory logger-ns]
      (if (= "namespace.you.want.to.silence" (str logger-ns))
        (logger-with-levels (log-impl/get-logger default-factory logger-ns) #{:warn})
        (log-impl/get-logger default-factory logger-ns)))))

There's room for improvement, polish, and optimization here, but it looks like all the necessary pieces are available to implement the desired functionality.

Personally, I'd lean towards putting this sort of thing in backend-specific configuration files, but that's explicitly not what you wanted. :)

Answered: Fix typo at README for `result is 1/2`

Wed, 26 Jun 2019 12:00:00 +0000

Reference: https://clojure.atlassian.net/browse/TLOG-22 (reported by pfeodrippe)

Answered: log/info removes quotes from strings making debugging harder than it needs to be.

Wed, 26 Jun 2019 12:00:00 +0000

Reference: https://clojure.atlassian.net/browse/TLOG-20 (reported by llsouder)