MT#16387 Report pending requested reboots

There are some times when a configuration, service or system upgrade
requires a reboot to take effect. When a component requires a reboot,
it will record this fact in the file system through the file
«/var/run/reboot-required», and «ngcpcfg status» will notify the user
that a reboot has been requested.

We use the «/var/run/reboot-required» because it is already being used
in the unattended-upgrades package on Debian/Ubuntu which does something
similar.

Change-Id: I43997bfb83892f67bd57bb55ad3ec0a41a5e088d

etc/ngcp-config/ngcpcfg.cfg

@@ -32,6 +32,9 @@ TIME_FORMAT="+%F %T"
 # directory holding files for internal state of ngcpcfg
 TIMESTAMP_DIR='/var/lib/ngcpcfg/timestamps/'
 
+# Run-time state directory
+RUN_DIR='/var/run'
+
 # validate configs using kwalify schema
 VALIDATE_SCHEMA="false"
 ## END OF FILE #################################################################

scripts/status

@@ -147,12 +147,26 @@ check_pending_actions() {
   fi
 }
 
+check_reboot_requests() {
+  log_debug "check_requested_reboot"
+
+  log_info "Checking for pending reboot requests:"
+
+  if [ -f "${RUN_DIR}/reboot-required" ]; then
+    log_info "ACTION_NEEDED: configuration, service or system changes requested a reboot"
+    log_info "-> reboot the system at your earliest convenience"
+  else
+    log_info "OK:     no reboot requested"
+  fi
+}
+
 if [ -z "${1:-}" ] ; then
   check_local_state
   check_push
   check_etc_state
   check_pending_actions
   check_shared_storage "$@"
+  check_reboot_requests
 fi
 
 check_remote "$@"