title: Speeding up SBT-assembly
body: <p>We have a project where we are building a large number of <a href="http://www.scalatra.org/" rel="noreferrer">Scalatra</a> <a href="http://martinfowler.com/articles/microservices.html" rel="noreferrer">microservices</a> by packaging them using the <a href="https://github.com/sbt/sbt-assembly" rel="noreferrer">sbt-assembly</a> plugin, then creating Docker images using the <a href="https://github.com/marcuslonnberg/sbt-docker" rel="noreferrer">sbt-docker</a> plugin. The process is slow due to the number of micro-services because the assembly plugin has to process all the transitive dependencies for each service. However I note most of the micro-services have very similar dependencies. Is there any way to speed this up? </p>
  
  <p>One limitation is we are doing this on Jenkins (CI) server so we are calling <code>sbt clean</code> at the start so we are not able to take advantage of any caching?</p>