1.0.1 docs





    Apr 27, 2018

    Nicolas Berger


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    The README below is fetched from the published project artifact. Some relative links may be broken.

    Ring-logger Circle CI

    Ring middleware to log response time and other details of each request that arrives to your server.

    • Logs request start, finish, parameters and exceptions by default.
    • The user can choose which of those messages to log by using the more specific middleware.
    • “Logs as data”: Log messages are simple clojure maps. You can provide a transform-fn to transform to other representations (string, JSON).
    • Uses by default, accepts a log-fn for switching to other log backends (timbre, etc.)


    Clojars Project

    Getting started

    Add the dependency to your project:

        [ring-logger "1.0.0"]


    Add the middleware to your ring stack:

        (ns foo
          (:require [ring.adapter.jetty :as jetty]
                    [ring.logger :as logger]))
        (defn my-ring-app [request]
             {:status 200
              :headers {"Content-Type" "text/html"}
              :body "Hello world!"})
        (jetty/run-jetty (logger/wrap-with-logger my-ring-app) {:port 8080})

    Example output:

    INFO  ring.logger: {:request-method :get, :uri "/", :server-name "localhost", :ring.logger/type :starting}                                                                                                  
    DEBUG ring.logger: {:request-method :get, :uri "/", :server-name "localhost", :ring.logger/type :params, :params {:name "ring-logger", :password "[REDACTED]"}}                                             
    INFO  ring.logger: {:request-method :get, :uri "/", :server-name "localhost", :ring.logger/type :finish, :status 200, :ring.logger/ms 11}

    Advanced usage

    ring.logger comes with more fine-grained middleware apart from wrap-with-logger:

    • wrap-log-request-start: Logs the start of the request
    • wrap-log-response
    • wrap-log-request-params: Logs the request parameters, using redaction to hide sensitive values (passwords, tokens, etc)

    To log just the start and finish of requests (no parameters):

        (-> handler
            ;; more middleware to parse params, cookies, etc.

    To measure request latency, wrap-log-response will use the ring.logger/start-ms key added by wrap-log-request-start if both middlewares are being used, or will call System/currentTimeMillis to obtain the value by itself.

    Using other loggging backends

    Other logging backends can be plugged by passing the log-fn option. This is how you could use timbre instead of c.t.logging:

        (require '[timbre.core :as timbre])
        (-> handler
            (logger/wrap-log-response {:log-fn (fn [{:keys [level throwable message]}]
                                                 (timbre/log level throwable message))}))

    What gets logged

    • an :info level message when a request begins.
    • a :debug level message with the request parameters (redacted).
    • an :info level message when a response is returned without server errors (i.e. its HTTP status is < 500), otherwise an :error level message is logged.
    • an :error level message with a stack trace when an exception is thrown during response generation.

    All messages will be usually timestamped by your logging infrastructure.

    How to disable exceptions logging

    This is especially useful when also using ring.middleware.stacktrace.

    (wrap-with-logger app {:log-exceptions? false})

    Password: “[REDACTED]”

    Sensitive information in params and headers can be redacted before it’s sent to the logs.

    This is very important: Nobody wants user passwords or authentication tokens to get to the logs and live there forever, in plain text, right?

    By default, ring-logger will redact any parameter whose name is in the ring.logger/default-redact-key? set (:password, :token, :secret, etc). You can pass your own set or function to determine which keys to redact as the redact-key? option

    (wrap-with-logger app {:redact-key? #{:senha :token})

    Logging only certain requests

    If you wish to restrict logging to certain paths (or other conditions), combine ring-logger with ring.middleware.conditional, like so:

    (:require [ring.middleware.conditional :as c :refer  [if-url-starts-with
    (def my-ring-app
       (-> handler
           (if-url-starts-with "/foo" wrap-with-logger)
            ;; Or:
            ;; (c/if some-test-fn wrap-with-logger)
            ;; etc.

    Consult the ring.middleware.conditional docs for full details.

    Similar projects

    pjlegato/ring.middleware.logger: ring-logger started as a fork of ring.middleware.logger. It’s a great option if you don’t mind pulling a transitive dependency on onelog & log4j.

    lambdaisland/ring.middleware.logger: a fork of r.m.logger that replaces onelog with


    Pull requests are welcome!


    Copyright (C) 2015-2018 Nicolás Berger Copyright (C) 2012-2014 Paul Legato.

    Distributed under the Eclipse Public License, the same as Clojure.