Maven Repository proxies third-party repositories, does this produce traffic?

Question

We have a public Sonatype Nexus Maven Repository which is a proxy for several third-party repositories, such as JBOSS or the Scala-Repo.

Does the downloading of artifacts which are located in one of the proxied repositories (JBOSS for example) produce traffic on the sever which runs our repository?

Answer 1

Here is what happens for released artifacts (SNAPSHOT would involve more checks):

1. Client Machine: Do I have a dependency in my local repository? If yes, use it. If no, try to download it from a remote repository (Nexus here).
2. Nexus: Do I have the artifact? If yes, serve it to the client. If no, try to get it from a known third-party repository, store it and serve it.
3. Third-party repository: Do I have the artifact? If yes, serve it to the client (Nexus in this case). If no, send 404.

So, there is potentially traffic between the client machine and Nexus and there is potentially traffic between Nexus and a third-party repository. If this doesn't answer the question, please clarify.

Answer 2

Yes it can, particularly for snapshots and whenever maven asks for the maven-metadata.xml (which is used in snapshots or version range resolution). This can be optimized using routing rules to prevent for example com/yourcompany from ever being resolved from jboss or central etc.