Nexus Plugin API

January 22, 2009
By Brian Fox

2 minute read time

We have mentioned that the Sonatype Nexus Repository features are just plugins to the OSS core, but we haven't yet formally discussed it. This blog post is an attempt to introduce the Nexus plugin API.

Most of the architectural work done to Nexus in the 1.1, 1.2, 1.3 releases has been done to build and enhance the plugin model and convert existing 1.0 features to the new model. Right now, a Nexus plugin is essentially a jar containing plexus components and resources, such as JavaScript, alongside a simple descriptor. Nexus plugins can add new REST services, add components that affect a request, and even add new UI elements and menu options to the user interface. A look at the functionality defined by each of the Pro features gives a good overview of how significant a plugin can be:

• LDAP - The LDAP plugin contributes a new security realm, associated REST services, privileges and extends the existing ajax UI panels.

• Staging and promotion - This plugin contributes a whole new type of Nexus Managed repository and REST resources / UI to manage it. What's different about this plugin is that it can hook into the configuration and create/delete repositories on the fly and the core can still understand the existence of the repos.

• Procurement - This plugin also adds REST, privileges, new UI panels like the others. It goes a step further and introduces a new remote repository type to handle the plugin firewall logic.

• P2 proxy - This plugin contributes entirely new repository content types to handle P2. So now instead of just M1/M2 you get P2. Following this model, a plugin could add content types for things like RPMs, Ruby Gems, etc.

Plugins can also:

• Attach to the event system and process incoming streams in real time.

• Introduce new scheduled tasks (new repo types can communicate with the scheduled tasks to prevent certain things from occurring; for example, the procurement repo blocks out any purge tasks regardless of the source).

• Extend any UI panel and introduce new ones with left nav items.

• Override or redefine existing UI resources.

• ...and, much, much more... the entire Nexus system is comprised of Plexus components that can be rewired on-demand.

The current plugin model requires a restart of Nexus to introduce new plugins. Jason has built a plugin manager based on the Maven plugin model, and work is already underway to integrate this into Nexus 1.4. The plugin manager will allow plugins to be loaded/unloaded/reloaded in real time without restarting the system. Full API documentation and examples are under construction and will be covered in future versions of the Nexus Book.

Extending Nexus With Plugins

All further functionality we build, both OSS core and Pro will be built as a plugin, which means the plugin model will expand and become more robust over time. It's not an unused API sitting idle.

Justin Edelson has already come forward with a Crowd plugin for Nexus, and a release is imminent in the Sonatype Forge - Nexus Plugins project. This will be a significant milestone, as it represents the first plugin built and released entirely outside the core Nexus team. There have also been many simple LDAP plugins created by third-parties. While we certainly believe our own LDAP is more capable, the fact that there are already competing options is a testament to the flexibility of the product.

If you have a Nexus plugin or want to write one, please ping us on the Nexus Developer list. We will provide SVN, Jira, Confluence and Nexus repository services via the Sonatype Forge to support this effort.

Written by Brian Fox

Brian Fox, CTO and co-founder of Sonatype, is a Governing Board Member for the Open Source Security Foundation (OpenSSF), a Governing Board Member for the Fintech Open Source Foundation (FINOS), a member of the Monetary Authority of Singapore Cyber and Technology Resilience Experts (CTREX) Panel, a member of the Apache Software Foundation and former Chair of the Apache Maven project. Working with OpenSSF, Brian helped create The Open Source Consumption Manifesto, urging organizations to elevate awareness of open source usage. He also chaired efforts to provide official responses to requests for information from the The Office of the National Cybersecurity Directorate (ONCD) and the Cybersecurity and Infrastructure Security Agency (CISA). Within the Atlantic Council's Open Source Policy Network, Brian actively helps shape cybersecurity strategy, offering valuable insights on critical documents, such as ONCD's recent National Cyber Security Strategy. Brian has over 20 years of experience driving the vision behind, as well as developing and leading the development of software for organizations ranging from startups to large enterprises. Brian is a frequent speaker at national and regional events including Java User Groups and other security and development-related conferences.