fix #35: add configurable randomized delay flag and behavior

Cargo.lock

@@ -1,6 +1,6 @@
 [root]
 name = "systemd-crontab-generator"
-version = "1.0.0-rc7"
+version = "1.0.0-rc8"
 dependencies = [
  "cronparse 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "docopt 0.6.78 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "systemd-crontab-generator"
-version = "1.0.0-rc7"
+version = "1.0.0-rc8"
 description = "Systemd generator for crontab files support"
 readme = "README.md"
 repository = "https://github.com/systemd-cron/systemd-cron-next"
@@ -10,7 +10,7 @@ build = "build.rs"
 keywords = ["cron", "crontab", "systemd", "generator"]
 
 [features]
-default = ["sched-boot", "sched-hourly", "sched-daily", "sched-weekly", "sched-monthly"]
+default = ["sched-boot", "sched-hourly", "sched-daily", "sched-weekly", "sched-monthly", "randomized-delay"]
 
 sched-boot = []
 sched-hourly = []
@@ -21,6 +21,7 @@ sched-yearly = []
 sched-minutely = []
 sched-quarterly = []
 sched-semi-annually = []
+randomized-delay = []
 persistent = []
 
 [build-dependencies]

Makefile.in

@@ -4,6 +4,7 @@ version		:= $(shell awk '/^version =/ { gsub("\"", "", $$3); print $$3; exit }'
 
 schedules			:= @schedules@
 enable_persistent	:= @enable_persistent@
+enable_randomized_delay	:= @enable_randomized_delay@
 
 prefix		:= @prefix@
 bindir		:= @bindir@
@@ -41,6 +42,7 @@ endef
 
 null :=
 persistent = $(if $(filter $(enable_persistent),yes),persistent,)
+randomized_delay = $(if $(filter $(enable_randomized_delay),yes),randomized-delay,)
 
 all: build
 
@@ -66,7 +68,7 @@ build: all
 	    BIN_DIR="$(bindir)" CONF_DIR="$(confdir)" MAN_DIR="$(mandir)" DOC_DIR="$(docdir)" \
 	    DATA_DIR="$(datadir)" LIB_DIR="$(libdir)" UNIT_DIR="$(unitdir)" \
 	    cargo install --path $(CURDIR) --root $(builddir) \
-	    --features "$(foreach schedule,$(schedules),sched-$(schedule)) $(persistent)"
+	    --features "$(foreach schedule,$(schedules),sched-$(schedule)) $(persistent) $(randomized_delay)"
 
 install: build
 	install -m2755 -g `getent group cron || echo root` -s -D $(builddir)/bin/crontab $(DESTDIR)$(bindir)/crontab

README.md

@@ -87,6 +87,7 @@ To further control cron jobs, use `cron.target` unit.
     * systemd ≥ 209, yearly timers
     * systemd ≥ 212, persistent timers
     * systemd ≥ 217, minutely, quarterly & semi-annually timers
+    * systemd ≥ 229, real random delay support with `RandomizedDelaySec` option
 * [run-parts][]
 * /usr/sbin/sendmail (optional, evaluated at runtime)
 
@@ -155,6 +156,8 @@ Other options include:
   Default: `no`.
 * `--enable-persistent[=yes|no]` Make timers [persistent][5]. Requires systemd ≥ 212.
   Default: `no`.
+* `--enable-randomized-delay=[yes|no]` Use [`RandomizedDelaySec`][6] option for `RANDOM_DELAY` support. Requires systemd ≥ 229.
+  Default: `yes`.
 
 A typical configuration for the latest systemd would be:
 
@@ -164,6 +167,8 @@ If you only want the generator (you'll have to provide your own `/etc/crontab` t
 
     $ ./configure --enable-boot=no --enable-hourly=no --enable-daily=no --enable-weekly=no --enable-month=no --enable-persistent --prefix=/usr --confdir=/etc
 
+[5]: https://www.freedesktop.org/software/systemd/man/systemd.timer.html#RandomizedDelaySec=
+
 ### Caveat
 
 Your package should also run these extra commands before starting cron.target

configure

@@ -29,6 +29,9 @@ enable_minutely=no
 enable_quarterly=no
 enable_semi_annually=no
 
+# systemd ≥ 229
+enable_randomized_delay=yes
+
 ARGS=$(getopt -n "$(basename "${0}")" -o '' -l '
 prefix:,
 bindir:,
@@ -50,6 +53,7 @@ enable-quarterly::,
 enable-semi_annually::,
 enable-yearly::,
 enable-persistent::,
+enable-randomized-delay::,
 ' -- "${@}")
 
 if [ $? -ne 0 ]; then
@@ -151,6 +155,10 @@ do
             set_enable_flag persistent ${2}
             shift 2;;
 
+        '--enable-randomized-delay')
+            set_enable_flag randomized_delay ${2}
+            shift 2;;
+
         '--')
             shift
             break;;
@@ -190,6 +198,7 @@ echo '# Generated by ./configure' > Makefile
 sed "
 s|@schedules@|${schedules}|g
 s|@enable_persistent@|${enable_persistent}|g
+s|@enable_randomized_delay@|${enable_randomized_delay}|g
 s|@prefix@|${prefix}|g
 s|@bindir@|${bindir}|g
 s|@confdir@|${confdir}|g

src/generate.rs

@@ -285,7 +285,11 @@ Unit={service_unit_name}"###,
             }
 
             if random_delay != 1 {
-                try!(writeln!(timer_unit_file, "AccuracySec={}m", random_delay));
+                if cfg!(feature="randomized-delay") {
+                    try!(writeln!(timer_unit_file, "RandomizedDelaySec={}m", random_delay));
+                } else {
+                    try!(writeln!(timer_unit_file, "AccuracySec={}m", random_delay));
+                }
             }
         }
         try!(symlink(timer_unit_path, cron_target_wants_path.join(timer_unit_name)));