solr/src/main/assembly/assembly.xml

<assembly>
  <id>bin</id>
  <formats>
    <format>tar.gz</format>
  </formats>
  <includeBaseDirectory>false</includeBaseDirectory>
  <baseDirectory>solr</baseDirectory>
  <includeSiteDirectory>false</includeSiteDirectory>
  <fileSets>
    <fileSet>
      <directory>${basedir}/src/main/resources</directory>
      <outputDirectory>solr</outputDirectory>
      <includes/>
      <fileMode>664</fileMode>
      <directoryMode>775</directoryMode>
    </fileSet>
  </fileSets>
</assembly>