Alternating karaf versions between 2.4 and master

Change-Id: I27373a03c234fe818efa184554ff333eccb8bf87
diff --git a/jjb/pipeline/voltha-scale-test.groovy b/jjb/pipeline/voltha-scale-test.groovy
index 3e2963f..42276a4 100644
--- a/jjb/pipeline/voltha-scale-test.groovy
+++ b/jjb/pipeline/voltha-scale-test.groovy
@@ -437,7 +437,8 @@
         done
 
         # copy the ONOS logs directly from the container to avoid the color codes
-        printf '%s\n' $(kubectl get pods -l app=onos-onos-classic -o=jsonpath="{.items[*]['metadata.name']}") | xargs -I@ bash -c "kubectl cp @:apache-karaf-4.2.9/data/log/karaf.log $LOG_FOLDER/@.log"
+        # TODO remove hardcoded karaf version
+        printf '%s\n' $(kubectl get pods -l app=onos-onos-classic -o=jsonpath="{.items[*]['metadata.name']}") | xargs -I@ bash -c "kubectl cp @:${karafHome}/data/log/karaf.log $LOG_FOLDER/@.log"
       '''
       // dump all the BBSim(s) ONU informations
       sh '''