[Static DNS] Optimize DNS configuration update during interface-confi…

…g service restart

files/image_config/interfaces/interfaces-config.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+resolvconf_updates=true
 
 function wait_networking_service_done() {
     local -i _WDOG_CNT="1"
@@ -23,6 +24,24 @@ function wait_networking_service_done() {
     systemctl kill networking 2>&1
 }
 
+function resolvconf_updates_disable() {
+    resolvconf --updates-are-enabled
+    if [[ $? -ne 0 ]]; then
+        resolvconf_updates=false
+    fi
+    resolvconf --disable-updates
+}
+
+function resolvconf_updates_restore() {
+    if [[ $resolvconf_updates == true ]]; then
+        resolvconf --enable-updates
+    fi
+}
+
+# Do not run DNS configuration update during the shutdowning of the management interface. 
+# This operation is redundant as there will be an update after the start of the interface.
+resolvconf_updates_disable
+
 if [[ $(ifquery --running eth0) ]]; then
     wait_networking_service_done
     ifdown --force eth0
@@ -61,6 +80,8 @@ for intf_pid in $(ls -1 /var/run/dhclient*.Ethernet*.pid 2> /dev/null); do
 done
 
 /usr/bin/resolv-config.sh cleanup
+# Restore DNS configuration update to the previous state.
+resolvconf_updates_restore
 
 # Read sysctl conf files again
 sysctl -p /etc/sysctl.d/90-dhcp6-systcl.conf

files/image_config/resolv-config/update-containers

@@ -1,6 +1,11 @@
 #!/bin/bash
 
-for container in $(docker ps -a --format=" {{ .ID }}"); do
+networking_status=$(systemctl is-active networking.service 2>/dev/null)
+if [[ $networking_status != "active" ]]; then
+    exit 0
+fi
+
+for container in $(docker ps -q); do
     docker cp -L /etc/resolv.conf ${container}:/_resolv.conf
     docker exec -t ${container} bash -c "cat /_resolv.conf > /etc/resolv.conf"
     docker exec -t ${container} bash -c "rm /_resolv.conf"