Repository Management with Nexus

6.3. Managing Groups

Groups are a powerful feature of Nexus. They allow you to combine multiple repositories and other repository groups in a single URL. Use the left-hand panel Repositories menu item in the Views/Repositories menu to access the repositories and groups management interface.

Nexus ships with one group: public. The Public Repositories group combines the multiple important external proxy repositories like the Central Repository with the hosted repositories: 3rd Party, Releases, and Snapshots.

In Section 4.2, “Apache Maven” we configured Maven via the settings.xml to look for artifacts in the public group managed by Nexus. Figure 6.18, “Group Configuration Screen in Nexus” shows the group configuration screen in Nexus. In this figure you can see the contents of the Public Repositories group.


Figure 6.18. Group Configuration Screen in Nexus

Note that the order of the repositories listed in Ordered Group Repositories is important. When Nexus searches for an artifact in a group, it will return the first match. To reorder a repository in this list, click and the drag the repositories and groups in the Ordered Group Repositories selection list.

The order of repositories or other groups in a group can be used to influence the effective metadata that will be retrieved by Maven from a Nexus Repository Group. We recommend placing hosted repositories higher in the list than proxy repositories within the list. For proxy repositories Nexus needs to periodically check the remote for updates, which will incur more overhead than a hosted repository lookup.

We also recommend placing repositories with a higher probability of matching the majority of artifacts higher in this list. If most of your artifacts are going to be retrieved from the Central Repository, putting Central higher in this list than a smaller, more focused repository is going to be better for performance, as Nexus is not going to interrogate the smaller remote repository for as many missing artifacts.