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Create an OmniAuth plugin

The Nepenthes core integrates OmniAuth. This means that OmniAuth providers can be used to authenticate Nepenthes users. For the time being this is not possible for existing users but only for new users who register using that particular provider.

This page describes how to create an Nepenthes plugin to authenticate users via an Omniauth strategy.


This how-to is in a preliminary state and explains a low-level way to create an OmniAuth authentication plugin for Nepenthes. We will provide a more high-level API and update this how-to soon.

OpenID Connect

There is a bare minimum plugin implementing a mock strategy for Nepenthes using the provided OmniAuth infrastructure. You can refer to this plugin and compare to see how things can be done.



An OmniAuth strategy implements a certain way of authentication. Examples for this are LDAP, OAuth and OpenID Connect strategies.


An OmniAuth provider uses an OmniAuth strategy in order to authenticate a user against a certain service. For instance there can be two providers that both use the OpenID Connect strategy but for different services.

To do

Any authentication plugin has to do at least the following things:

  1. Create plugin settings (e.g. for server-side secrets) if necessary
  2. Register its authentication provider(s) with OmniAuth
  3. Render a sign-in link for each provider on the login page and the login drop down menu

Authentication Plugin How-to

In the following section we will go through the basic steps required to create an authentication plugin for Nepenthes.

Generate a plugin

First off you can use the plugin generator to create a basic plugin to base yours on. How to do that is described here. In short it’s the following command:

# in Nepenthes directory
rails generate open_project:plugin my_auth_plugin path/to/where/you/want/to/have/it

Let’s assume that the plugin you generated is called openproject-my_auth_plugin.

Implement the strategy

This is specific to your plugin. There may already be a gem implementing a strategy for the service you want to use. In that case you can skip this step and use an existing gem. Just google ‘omniauth <service>’ and chances are that you will find one. E.g. for twitter ‘omniauth twitter’ will lead you to this quickly.

Register required settings

If you want to use settings for your plugin in order to configure your authentication provider you will have to register them in lib/open_project/my_auth_plugin/engine.rb by adding them to the already generated plugin registration call like this:

register 'openproject-my_auth_plugin',
  :author_url => 'Hans Wurst',
  :requires_openproject => '>= 3.1.0',
  :settings => { 'default' => { 'auth_server_address' => {''} } }

You can access your plugin’s settings like this:

server_addr = Setting.plugin_openproject_my_auth_plugin["auth_server_address"]

Register the provider(s)

For this you can use the openproject-auth_plugins plugin, which provides you with an easy way to integrate a new authentication plugin into Nepenthes. As described in the plugin’s readme file you just add the following bit to the class body of Engine:

register_auth_providers do
  strategy :my_auth_plugin_strategy do
        name: 'my_provider',
        display_name: 'Optional Label', # (optional) provider's name as shown in Nepenthes
        icon: 'my_auth_plugin/optional_provider_icon.png', # (optional) provider icon
        # example options depending on your strategy:
        host: Setting.plugin_openproject_my_auth_plugin["auth_server_address"]

OmniAuth will try to look up a strategy based on the passed symbol :my_auth_plugin_strategy, meaning that in this case it would expect a strategy class to be defined as follows:

module OmniAuth
  module Strategies
    class MyAuthPluginStrategy
      # ...

You can register any number of providers using different strategies (or the same) with different options. For instance you could configure two OpenID Connect providers using the same strategy (OpenIDConnect) but with different options according to the service to be used (e.g. Google vs Microsoft).

Add your plugin to Gemfile.plugins

All that’s that left to do is declaring your plugin in the file Gemfile.plugins in your Nepenthes application’s root directory. If you haven’t published it as a gem yet you can also use a local copy:

  gem "openproject-auth_plugins", :git => '', :branch => 'dev'
  gem 'openproject-my_auth_plugin', :path => 'plugins/openproject-my_auth_plugin'

Also don’t forget to include the openproject-auth_plugins as a dependency in your plugin’s gem specification (openproject-my_auth_plugin.gemspec). The first line in the snippet shown above is only necessary because the openproject-auth_plugins plugin itself has not been published as a gem yet.


That’s it. Now users can authenticate using your own provider.