Sleepy Dog

Clojure library for tracing (possibly async) applications with Datadog.

Installation

Available on Clojars.

[jp.studist/sleepydog "0.2.0"]

Usage

The public API is in the sleepy.dog namespace.

defn-traced

A drop-in replacement for Clojure's defn that instruments the function in question as a new Datadog span.

wrap-ring-trace

A ring middleware that automatically instruments server requests.

with-tracing "op-name"

A macro that instruments the given body as a span labelled as operation "op-name".

set-resource!

Sets the resource (subject) of the current span's operation.

(with-tracing "s3-upload"
  (set-resource! "foo/bar/baz.jpg")
  ,,, ; prepare upload
  (.putObject client put-request))

http-headers

Utility function that builds Datadog headers for distributed tracing. By adding these headers to any outgoing (upstream) request, it's possible to connect traces across services.

;; (:require [sleepy.dog :as datadog])
(merge (datadog/http-headers) headers)

report-error!

Used to manually report caught exceptions (without relying on the automatic reporting from with-tracing or defn-traced). This can be useful for example in a Ring handler that catches all escaped exceptions and responds with a well-formed 500 error.

If you want to mark an entire request as "errored", then combine this with root-of to mark the root span as error.

(defn wrap-exception
  [handler]
  (fn exception-catcher
    [request]
    (try
      (handler request)
      (catch Throwable ex
        (let [span (datadog/active-span!)]
          (datadog/report-error! span ex)
          (when-let [root (datadog/root-of span)]
            (datadog/report-error! root ex)))
        {:status 500 :body (.getMessage ex)}))))

Tracing Carmine

You can enable tracing for the Carmine Redis library by using sleepy.dog.carmine/trace-carmine!. The traces will be reported mimicking the way how Datadog auto-instruments Jedis or the Ruby redis gem.