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A library for starting a web server to serve a Ring handler with sensible default options and environment variable overrides.


When starting in development mode (i.e. LEIN_NO_DEV is not set):

  • The server finds a free port to start on
  • It automatically reloads changed files
  • It renders exceptions and their stacktraces in HTML
  • A web browser is automatically opened to the started server

In production:

  • You can specify the port via the PORT environment variable
  • You can add hooks to run on startup and shutdown.


Add the following dependency to your project.clj file:

[ring-server "0.2.5"]


Simple usage:

(use 'ring.server.standalone)
(serve your-handler)

You can also specify a map of options:

(serve your-handler {:port 4040})

The following options are supported:

  • :port - The port to start the server on, overrides $PORT

  • :join? - Whether to wait until the server stops (default true)

  • :init - A function executed when the server starts

  • :destroy - A function executed when the server stops

  • :open-browser? - True if you want a browser to be opened to the server. Defaults to true in development mode, false in production mode.

  • :stacktrace? - True if you want a stacktrace to be displayed in the browser when an exception is raised. Default to true in development, false in production.

  • :auto-reload? - True if you want your source files to be automatically reloaded when they are modified. Defaults to true in development, false in production.

  • :auto-refresh? - True if you want your browser to automatically refresh when source files are changed. Defaults to false.


Copyright (C) 2012 James Reeves

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