Call an environment specific value-adding activity from within a Go template

gistfile1.txt

    <pipeline name="deploy">
      <stage name="deploy">
        <jobs>
          <job name="deploy">
            <tasks>
              <exec command="bundle" workingdir="rpm">
                <arg>install</arg>
                <arg>--quiet</arg>
                <arg>--path</arg>
                <arg>/var/go/gems</arg>
                <runif status="passed" />
              </exec>
              <rake target="deploy:all" workingdir="rpm">
                <runif status="passed" />
              </rake>
              <rake target="deploy:smoke" workingdir="rpm">
                <runif status="passed" />
              </rake>
            </tasks>
            <resources>
              <resource>deployer</resource>
            </resources>
          </job>
        </jobs>
      </stage>
      <stage name="awesomeness">
        <environmentvariables>
          <variable name="GEM_DIR">
            <value>/var/go/gems</value>
          </variable>
        </environmentvariables>
        <jobs>
          <job name="awesomeness">
            <tasks>
              <exec command="bundle" workingdir="rpm">
                <arg>install</arg>
                <arg>--quiet</arg>
                <arg>--path</arg>
                <arg>/var/go/gems</arg>
                <runif status="passed" />
              </exec>
              <exec command="bash" workingdir="rpm">
                <arg>-c</arg>
                <arg>bundle exec rake GEM_DIR=${GEM_DIR} awesomeness:${GO_PIPELINE_NAME}</arg>
                <runif status="passed" />
              </exec>
            </tasks>
            <resources>
              <resource>deployer</resource>
            </resources>
          </job>
        </jobs>
      </stage>
    </pipeline>