Introduction of a new helper-handler pair named nap

The .nap file can be created to freeze the processing of the configurations for a (static) random interval. It is possible to specify the interval in seconds with a min and a max value and if it should be static.

Change-Id: I9523fd3645b1007fe7e24b6bd4ec18a104a07e05

handlers/Makefile.am

@@ -1,10 +1,10 @@
 
 HANDLERS = borg borg.helper dup dup.helper maildir makecd	\
-         makecd.helper mysql mysql.helper pgsql pgsql.helper rdiff	\
+         makecd.helper mysql mysql.helper nap nap.helper pgsql pgsql.helper rdiff	\
          rdiff.helper rsync sh svn sys sys.helper trac tar tar.helper
 
 DIST_HANDLERS = borg.in borg.helper.in dup.in dup.helper.in maildir.in makecd.in	\
-         makecd.helper.in mysql.in mysql.helper.in pgsql.in pgsql.helper.in rdiff.in	\
+         makecd.helper.in mysql.in mysql.helper.in nap.in nap.helper.in pgsql.in pgsql.helper.in rdiff.in	\
          rdiff.helper.in rsync.in sh.in svn.in sys.in sys.helper.in trac.in tar.in tar.helper.in wget
 
 CLEANFILES = $(HANDLERS)
@@ -62,6 +62,14 @@ mysql.helper: $(srcdir)/mysql.helper.in
 	rm -f mysql.helper
 	$(edit) $(srcdir)/mysql.helper.in > mysql.helper
 
+nap: $(srcdir)/nap.in
+	rm -f nap
+	$(edit) $(srcdir)/nap.in > nap
+
+nap.helper: $(srcdir)/nap.helper.in
+	rm -f nap.helper
+	$(edit) $(srcdir)/nap.helper.in > nap.helper
+
 pgsql: $(srcdir)/pgsql.in
 	rm -f pgsql
 	$(edit) $(srcdir)/pgsql.in > pgsql

handlers/nap.helper.in

@@ -0,0 +1,101 @@
+# nap.helper creates a configuration file to offer the possibility
+# to add a delay in form of a sleep before the start of the backup
+# process itself
+
+HELPERS="$HELPERS nap:randomized_delay_of_backups"
+
+do_nap_static_random_delay() {
+
+   # set a boolean value to enable a static random delay seeded with the machine-id in /etc/machine-id.
+   radioBox "$nap_title" "enable the static random delay. For more information check the doc's..." \
+      "true" "enable the static random delay" off \
+      "false" "default" on
+   [ $? -eq 1 ] && return
+   nap_static_random_delay=$REPLY
+   setDefault interval_min
+}
+
+
+do_nap_interval_min() {
+
+   msg="Specify a lower limit for the time span of the delay in seconds:"
+   # set the minimum delay for the interval
+   inputBox "$nap_title" "${msg}"
+   [ $? -eq 0 ] || return
+   nap_interval_min=$REPLY
+   _interval_min_done="(DONE)"
+   setDefault interval_max
+}
+
+do_nap_interval_max() {
+
+   msg="Specify a upper limit for the time span of the delay in seconds:"
+   # set the maximum delay for the interval
+   inputBox "$nap_title" "${msg}"
+   [ $? -eq 0 ] || return
+   nap_interval_max=$REPLY
+   _interval_max_done="(DONE)"
+   setDefault finish
+}
+
+do_nap_finish() {
+
+   # Uses the prefix 0.nap because it has to be the first file processed by the corresponding handler
+   # that the randomized delay becomes useful.
+
+   get_next_filename $configdirectory/1.nap
+   cat > $next_filename <<EOF
+### configuration file for nap.handler ###
+# This holds back the processing of configuration files in this directory
+# for a randomized and configurable time span
+
+nap_static_random_delay = $nap_static_random_delay
+nap_interval_min = $nap_interval_min
+nap_interval_max = $nap_interval_max
+EOF
+   chmod 600 $next_filename
+}
+
+nap_main_menu() {
+   while true; do
+      static_random_delay="enable the static random delay"
+      interval_min="specify the minimum delay for the interval $_interval_min_done"
+      interval_max="specify the maximum delay for the interval $_interval_max_done"
+      menuBox "$nap_title" "choose a step:" \
+         static "$static_random_delay" \
+         interval_min "$interval_min" \
+         interval_max "$interval_max" \
+         finish "finish and create configuration file"
+      [ $? -eq 0 ] || return
+         case "$REPLY" in
+            "static") do_nap_static_random_delay;;
+            "interval_min") do_nap_interval_min;;
+            "interval_max") do_nap_interval_max;;
+            "finish")
+               if [[ "$_interval_min_done$_interval_max_done" != "(DONE)(DONE)" ]]; then
+                  msgBox "$nap_title" "You cannot create the configuration file until mandatory steps are completed."
+               else
+                  do_nap_finish
+                  return
+               fi
+               ;;
+         esac
+   done
+}
+
+nap_wizard() {
+
+   # global variables
+   nap_title="random delay on backup process wizard"
+
+   _interval_min_done=
+   _interval_max_done=
+
+
+   # define some defaults for the configurations
+   nap_static_random_delay=true
+   nap_interval_min=
+   nap_interval_max=
+
+   nap_main_menu
+}

handlers/nap.in

@@ -0,0 +1,25 @@
+# nap.handler for processing the .nap files to freeze the processing of configurations
+# in the configuration directory of backupninja temporary.
+
+getconf nap_static_random_delay
+getconf nap_interval_min
+getconf nap_interval_max
+
+# check for static random delay
+if [ $nap_static_random_delay == "false" ]; then
+
+   # use perl rand if static random is set false
+   delay=$(perl -e "print int($nap_interval_min + rand($nap_interval_max - $nap_interval_min))")
+
+else
+
+   # seed rand with machine-id, the substring 0,8 is needed so the integer value does not
+   # overflows the max integer value of perl on a 32 bit system. With this method entropy isn't
+   # a problem
+   delay=$(cat /etc/machine-id | perl -e "srand(hex(substr(<STDIN>,0,8))); \
+      print int($nap_interval_min + rand($nap_interval_max - $nap_interval_min))")
+
+fi
+
+echo "Holding processing of configurations for $delay seconds..."
+perl -e "sleep $delay"