agent: Add logging to libvirt qemu hook (#2554)

This allows logging to the default libvirt qemu hook

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

agent/bindir/libvirtqemuhook.in

@@ -15,16 +15,27 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-import sys
+
+import logging
 import re
+import sys
 from xml.dom.minidom import parse
 from cloudutils.configFileOps import configFileOps
 from cloudutils.networkConfig import networkConfig
+
+logging.basicConfig(filename='/var/log/libvirt/qemu-hook.log',
+                    filemode='a',
+                    format='%(asctime)s,%(msecs)d %(name)s %(levelname)s %(message)s',
+                    datefmt='%H:%M:%S',
+                    level=logging.INFO)
+logger = logging.getLogger('qemu-hook')
+
 def isOldStyleBridge(brName):
     if brName.find("cloudVirBr") == 0:
        return True
     else:
        return False
+
 def isNewStyleBridge(brName):
     if brName.startswith('brvx-'):
         return False
@@ -32,12 +43,14 @@ def isNewStyleBridge(brName):
        return False
     else:
        return True
+
 def getGuestNetworkDevice():
     netlib = networkConfig()
     cfo = configFileOps("/etc/cloudstack/agent/agent.properties")
     guestDev = cfo.getEntry("guest.network.device")
     enslavedDev = netlib.getEnslavedDev(guestDev, 1)
     return enslavedDev.split(".")[0]
+
 def handleMigrateBegin():
     try:
         domain = parse(sys.stdin)
@@ -56,9 +69,15 @@ def handleMigrateBegin():
         print(domain.toxml())
     except:
         pass
+
+
 if __name__ == '__main__':
     if len(sys.argv) != 5:
         sys.exit(0)
 
-    if sys.argv[2] == "migrate" and sys.argv[3] == "begin":
+    # For docs refer https://libvirt.org/hooks.html#qemu
+    logger.debug("Executing qemu hook with args: %s" % sys.argv)
+    action, status = sys.argv[2:4]
+
+    if action == "migrate" and status == "begin":
         handleMigrateBegin()