How To Use Hosted Nexus With Sbt

If you work in an organization or doing your personal project sooner or latter you’re gonna need an artifact server. And few reasons this would be you want to host your build artifacts but not make those available to the public, you want to have a proxy server to use when you download your artifacts, this is particularly helpful when you have more than one person working on the project or you simply have some jars that aren’t in maven central or other public repos and you want to host those so you can list them as dependencies from your build tool.

My favorite artifact server is nexus for many reasons. It’s feature reach, easy to use and can support npm, gem, NuGet artifacts besides jars. So for our scala projects I decided to go with nexus. After artifacts are produced those aren’t any different from java ones so most of the work nexus already done for me when it came to setting up the repos. There is already a public repo which a group repo and combines Releases, Snapshots, Third Party and proxy for Central. Releases is where your release artifacts are stored, Snapshots for for snapshot deploys, Third Party is good to put your existing jars that aren’t in maven central or in any other public repo. Proxy for maven central repo is good so you can have the jars you’re using from community hosted in your server. You can add more proxy repos if you feel it’s appropriate.

For sbt I did need to create a separate group repo which is a combination of two proxy repos, one for http://repo.typesafe.com/typesafe/ivy-releases/ and other for http://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/.

Also I like to separate users who can deploy, who can use the artifacts instead of using admin user everywhere. And I do recommend disabling anonymous user so you’re strict about who has access to your artifacts.

Now it’s time to configure sbt to use our nexus server instead of public repos. Add following to cat ~/.sbt/repositories file

[repositories]
  local
    ivy-proxy-releases: <your ivy repo>, [organization]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]
    maven-proxy-releases:<your maven reop> 

Note that in order for sbt to get plugins from your repo also you have to run it with sbt.override.build.repos flag set to true. Consult sbt documentation for more info.

Since we decided to secure our nexus with authentication we need to tell sbt where what the credentials are, and the most elegant way to do it to store in credentials file. Create a file named ~/.sbt/.credentials to store the credentials. For build server you would put deployment user credentials, for developer computer developer credentials here.

realm=<realm here>
host=<host here>
user=<user name here>
password=<passord here>

You can find out what realm is by doing (most likey it’s Sonatype Nexus Repository Manager though):

curl -v -XHEAD <urt nexus url>/content/groups/public/

and look at WWW-Authenticate header.

For host just put the host name without port number.

Now in your plugins.sbt add

credentials += Credentials(Path.userHome / ".sbt" / ".credentials")

This is it. Now when you run sbt it will get dependencies from our repos. Publishing artifacts is also easy. I only let build server do it so the most elegant way to handle it is adding following to global.sbt file in build server.

publishTo := {
  val nexus = "your nexus server url"
  if (isSnapshot.value)
    Some("snapshots" at nexus + "content/repositories/snapshots")
  else
    Some("releases"  at nexus + "content/repositories/releases")
}

sbt publish will now publish the artifacts to our repo (don’t forget to put deployment user in credentials files on build server).

Happy and elegent builds guys,