Add migration selector via free memory

Closes #152

daemon-common/common.py

@@ -639,6 +639,8 @@ def findTargetNode(zkhandler, dom_uuid):
     # Execute the search
     if search_field == "mem":
         return findTargetNodeMem(zkhandler, node_limit, dom_uuid)
+    if search_field == "memfree":
+        return findTargetNodeMemFree(zkhandler, node_limit, dom_uuid)
     if search_field == "load":
         return findTargetNodeLoad(zkhandler, node_limit, dom_uuid)
     if search_field == "vcpus":
@@ -677,7 +679,7 @@ def getNodes(zkhandler, node_limit, dom_uuid):
 
 
 #
-# via free memory (relative to allocated memory)
+# via allocated memory
 #
 def findTargetNodeMem(zkhandler, node_limit, dom_uuid):
     most_provfree = 0
@@ -698,6 +700,24 @@ def findTargetNodeMem(zkhandler, node_limit, dom_uuid):
     return target_node
 
 
+#
+# via free memory
+#
+def findTargetNodeMemFree(zkhandler, node_limit, dom_uuid):
+    most_memfree = 0
+    target_node = None
+
+    node_list = getNodes(zkhandler, node_limit, dom_uuid)
+    for node in node_list:
+        memfree = int(zkhandler.read(("node.memory.free", node)))
+
+        if memfree > most_memfree:
+            most_memfree = memfree
+            target_node = node
+
+    return target_node
+
+
 #
 # via load average
 #

node-daemon/pvcnoded.sample.yaml

@@ -122,7 +122,7 @@ pvc:
         pass: Passw0rd
     # migration: Migration option configuration
     migration:
-      # target_selector: Criteria to select the ideal migration target, options: mem, load, vcpus, vms
+      # target_selector: Criteria to select the ideal migration target, options: mem, memfree, load, vcpus, vms
       target_selector: mem
     # configuration: Local system configurations
     configuration: