Nexus3 Github OAuth Plugin

This plugin adds a Github realm to Sonatype Nexus OSS and enables you to authenticate with Github Users and authorize with Github Orgs and Teams.

The plugin does not implement a full OAuth flow, instead you use your github user name + an OAuth token you generated in your account to log in to the nexus. This works through the web as well as through tools like maven, gradle etc.

Setup

1. Activate the Realm

Log in to your nexus and go to Administration > Security > Realms. Move the Github Realm to the right. The realm order in the form determines the order of the realms in your authentication flow. We recommend putting Github after the built-in realms:

2. Group / Roles Mapping

When logged in through Github, all organizations and teams the user is a member of will be mapped into roles like so:

organization name/team name e.g. dummy-org/developers

You need to manually create these roles in Administration > Security > Roles > (+) Create Role > Nexus Role in order to assign them the desired privileges. The Role ID should map to the organization name/team name. Note that by default anybody is allowed to login (authenticate) with a valid Github Token from your Github instance, but he/she won't have any privileges assigned with their teams (authorization) - see the config property github.org if you want to change that behaviour.

Usage

The following steps need to be done by every developer who wants to login to your nexus with Github.

1. Generate OAuth Token

In your github account under Settings > Personal access tokens generate a new OAuth token. The only scope you need is read:org

2. Login to nexus

When logging in to nexus, use your github user name as the username and the oauth token you just generated as the password. This also works through maven, gradle etc.

Example Maven settings.xml fragment:

<servers>
  <server>
    <id>Id that matches the id element of the repository/mirror that Maven tries to connect to</id>
    <username>Your Github user name</username>
    <password>Your Github token</password>
  </server>
</servers>

Installation

0. Prerequisites

Directory naming convention:

For the following commands we assume your nexus installation resides in /opt/sonatype/nexus. See https://books.sonatype.com/nexus-book/reference3/install.html#directories for reference.

1. Download and install

Download the latest release from github and place it in the nexus/deploy folder, e.g., like so:

wget -O /opt/sonatype/nexus/deploy/nexus3-github-oauth-plugin.kar https://github.com/larscheid-schmitzhermes/nexus3-github-oauth-plugin/releases/download/3.0.0/nexus3-github-oauth-plugin.kar

2. Create configuration

Create /opt/sonatype/nexus/etc/githuboauth.properties

Within the file you can configure the following properties:

Property	Description	Default
github.api.url	URL of the Github API to operate against.	https://api.github.com
github.principal.cache.ttl	Java Duration for how long a given Access will be cached for. This is a tradeoff of how quickly access can be revoked and how quickly a Github user's rate limit will be reached for the Github User API. Note: Github Enterprise does not have a rate limit!	PT1M (1 Minute)
github.org	The comma-separated list of Organizations the user should be a member of. If this is not set, anyone with a Github account is allowed to log in.	----
request.timeout.connection-request	The timeout in milliseconds used when requesting a connection from the connection manager. A timeout value of zero is interpreted as an infinite timeout. A negative value is interpreted as undefined (system default).	-1
request.timeout.connect	The timeout in milliseconds until a connection is established. A timeout value of zero is interpreted as an infinite timeout. A negative value is interpreted as undefined (system default).	-1
request.timeout.socket	The socket timeout (SO_TIMEOUT) in milliseconds, which is the timeout for waiting for data or, put differently, a maximum period inactivity between two consecutive data packets). A timeout value of zero is interpreted as an infinite timeout. A negative value is interpreted as undefined (system default).	-1

This is what an example file would look like:

github.api.url=https://github.example.com/api/v3 #note: no trailing slash!!!
github.principal.cache.ttl=PT1M

3. Restart Nexus

Restart your Nexus instance to let it pick up your changes.

Development

You can build the project with the integrated maven wrapper like so: ./mvnw clean package

You can also build locally using Docker by running docker run --rm -it -v $(pwd):/data -w /data maven:3.5.2 mvn clean package

You can build a ready to run docker image using the Dockerfile to quickly spin up a nexus with the plugin already preinstalled.

Credits

The whole project is heavily influenced by the nexus3-crowd-plugin.