+### this returns the kind of virtualization on the node
+# either 'vs' or 'lxc'
+# also caches it in /etc/planetlab/virt for next calls
+# could be promoted to core nm if need be
+virt_stamp="/etc/planetlab/virt"
+def get_node_virt ():
+ try:
+ return file(virt_stamp).read().strip()
+ except:
+ pass
+ logger.log("Computing virt..")
+ vs_retcod=subprocess.call ([ 'vserver', '--help' ])
+ if vs_retcod == 0:
+ virt='vs'
+ else:
+ virt='lxc'
+ with file(virt_stamp,"w") as f:
+ f.write(virt)
+ return virt
+
+def command_in_slice (slicename, argv):
+ # with vserver this can be done using vserver .. exec <trigger-script>
+ # with lxc this is less clear as we are still discussing how lxcsu should behave
+ # ideally we'd need to run lxcsu .. <trigger-script>
+ virt=get_node_virt()
+ if virt=='vs':
+ return [ 'vserver', slicename, 'exec', ] + argv
+ elif virt=='lxc':
+ return [ 'lxcsu', slicename, ] + argv
+ logger.log("command_in_slice: WARNING: could not find a valid virt")
+ return argv
+