CLOUDSTACK-5986: Make dnsmasq handle dnsmasq.leases when dhcp_release is available

The original issue has been exposed due to CloudStack VR would modify the
dnsmasq.leases, thus make it unsync with dnsmasq's memory lease.

Make the modification to let dnsmasq handle the lease file if dhcp_release is
available.
(cherry picked from commit 441d02dd40)

Signed-off-by: Animesh Chaturvedi <animesh@apache.org>

systemvm/patches/debian/config/etc/init.d/cloud-early-config

@@ -750,6 +750,16 @@ setup_dnsmasq() {
       sed -i -e "/^dhcp-client-update/d" /etc/dnsmasq.conf
       echo 'dhcp-client-update' >> /etc/dnsmasq.conf
   fi
+
+  command -v dhcp_release > /dev/null 2>&1
+  no_dhcp_release=$?
+  if [ $no_dhcp_release -eq 0 -a -z "$ETH0_IP6" ]
+  then
+      echo 1 > /var/cache/cloud/dnsmasq_managed_lease
+      sed -i -e "/^leasefile-ro/d" /etc/dnsmasq.conf
+  else
+      echo 0 > /var/cache/cloud/dnsmasq_managed_lease
+  fi
 }
 
 setup_sshd(){

systemvm/patches/debian/config/root/edithosts.sh

@@ -80,8 +80,7 @@ fi
 grep "redundant_router=1" /var/cache/cloud/cmdline > /dev/null
 no_redundant=$?
 
-command -v dhcp_release > /dev/null 2>&1
-no_dhcp_release=$?
+dnsmasq_managed_lease=`cat /var/cache/cloud/dnsmasq_managed_lease`
 
 wait_for_dnsmasq () {
   local _pid=$(pidof dnsmasq)
@@ -96,12 +95,7 @@ wait_for_dnsmasq () {
   return 1
 }
 
-if [ $ipv6 ]
-then
-    no_dhcp_release=1
-fi
-
-if [ $no_dhcp_release -eq 0 ]
+if [ $dnsmasq_managed_lease ]
 then
   #release previous dhcp lease if present
   logger -t cloud "edithosts: releasing $ipv4"
@@ -145,27 +139,30 @@ then
   fi
 fi
 
-#delete leases to supplied mac and ip addresses
-if [ $ipv4 ]
+if [ $dnsmasq_managed_lease -eq 0 ]
 then
-  sed -i  /$mac/d $DHCP_LEASES 
-  sed -i  /"$ipv4 "/d $DHCP_LEASES 
-fi
-if [ $ipv6 ]
-then
-  sed -i  /$duid/d $DHCP_LEASES 
-  sed -i  /"$ipv6 "/d $DHCP_LEASES 
-fi
-sed -i  /"$host "/d $DHCP_LEASES 
+  #delete leases to supplied mac and ip addresses
+  if [ $ipv4 ]
+  then
+    sed -i  /$mac/d $DHCP_LEASES
+    sed -i  /"$ipv4 "/d $DHCP_LEASES
+  fi
+  if [ $ipv6 ]
+  then
+    sed -i  /$duid/d $DHCP_LEASES
+    sed -i  /"$ipv6 "/d $DHCP_LEASES
+  fi
+  sed -i  /"$host "/d $DHCP_LEASES
 
-#put in the new entry
-if [ $ipv4 ]
-then
-  echo "0 $mac $ipv4 $host *" >> $DHCP_LEASES
-fi
-if [ $ipv6 ]
-then
-  echo "0 $duid $ipv6 $host *" >> $DHCP_LEASES
+  #put in the new entry
+  if [ $ipv4 ]
+  then
+    echo "0 $mac $ipv4 $host *" >> $DHCP_LEASES
+  fi
+  if [ $ipv6 ]
+  then
+    echo "0 $duid $ipv6 $host *" >> $DHCP_LEASES
+  fi
 fi
 
 #edit hosts file as well
@@ -215,7 +212,7 @@ pid=$(pidof dnsmasq)
 if [ "$pid" != "" ]
 then
   # use SIGHUP to avoid service outage if dhcp_release is available.
-  if [ $no_dhcp_release -eq 0 ]
+  if [ $dnsmasq_managed_lease ]
   then
     kill -HUP $pid
   else