dcron recipe: accept systemd calendar spec

This format must always be used in parameters to request instances.

See also http://www.freedesktop.org/software/systemd/man/systemd.timer.html
for online manpage.

slapos/recipe/dcron.py

@@ -26,7 +26,11 @@
 ##############################################################################
 import os
 
-from slapos.recipe.librecipe import GenericBaseRecipe
+if __name__ == '__main__': # Hack to easily run test below.
+  GenericBaseRecipe = object
+else:
+  from slapos.recipe.librecipe import GenericBaseRecipe
+  from zc.buildout import UserError
 
 class Recipe(GenericBaseRecipe):
 
@@ -51,18 +55,111 @@ class Recipe(GenericBaseRecipe):
     return [script]
 
 
-
 class Part(GenericBaseRecipe):
 
   def install(self):
+    try:
+      periodicity = self.options['frequency']
+    except KeyError:
+      periodicity = self.options['time']
+      try:
+        periodicity = systemd_to_cron(periodicity)
+      except Exception:
+        raise UserError("Invalid systemd calendar spec %r" % periodicity)
     cron_d = self.options['cron-entries']
     name = self.options['name']
     filename = os.path.join(cron_d, name)
 
     with open(filename, 'w') as part:
-      part.write('%(frequency)s %(command)s\n' % {
-        'frequency': self.options['frequency'],
-        'command': self.options['command'],
-      })
+      part.write('%s %s\n' % (periodicity, self.options['command']))
 
     return [filename]
+
+
+day_of_week_dict = dict((name, dow) for dow, name in enumerate(
+    "sunday monday tuesday wednesday thursday friday saturday".split())
+  for name in (name, name[:3]))
+
+def systemd_to_cron(spec):
+  """Convert from systemd.time(7) calendar spec to crontab spec"""
+  if spec in ("hourly", "daily", "monthly", "weekly"):
+    return '@' + spec
+  if not spec.strip():
+    raise ValueError
+  spec = spec.split(' ')
+  try:
+    dow = ','.join(sorted('-'.join(str(day_of_week_dict[x.lower()])
+                                   for x in x.split('-', 1))
+                          for x in spec[0].split(',')
+                          if x))
+    del spec[0]
+  except KeyError:
+    dow = '*'
+  day = spec.pop(0) if spec else '*-*'
+  if spec:
+    time, = spec
+  elif ':' in day:
+    time = day
+    day = '*-*'
+  else:
+    time = '0:0'
+  day = day.split('-')
+  time = time.split(':')
+  if (# years not supported
+      len(day) > 2 and day.pop(0) != '*' or
+      # some crons ignore day of month if day of week is given, and dcron
+      # treats day of month in a way that is not compatible with systemd
+      dow != '*' != day[1] or
+      # seconds not supported
+      len(time) > 2 and int(time.pop())):
+    raise ValueError
+  month, day = day
+  hour, minute = time
+  spec = minute, hour, day, month, dow
+  for x, (y, z) in zip(spec, ((0, 60), (0, 24), (1, 31), (1, 12))):
+    if x != '*':
+      for x in x.split(','):
+        x = map(int, x.split('/', 1))
+        x[0] -= y
+        if x[0] < 0 or len(x) > 1 and x[0] >= x[1] or z <= sum(x):
+          raise ValueError
+  return ' '.join(spec)
+
+def test(self):
+  def _(systemd, cron):
+    self.assertEqual(systemd_to_cron(systemd), cron)
+  _("Sat,Mon-Thu,Sun", "0 0 * * 0,1-4,6")
+  _("mon,sun *-* 2,1:23", "23 2,1 * * 0,1")
+  _("Wed, 17:48", "48 17 * * 3")
+  _("Wed-Sat,Tue 10-* 1:2", "2 1 * 10 2,3-6")
+  _("*-*-7 0:0:0", "0 0 7 * *")
+  _("10-15", "0 0 15 10 *")
+  _("monday *-12-* 17:00", "00 17 * 12 1")
+  _("12,14,13,12:20,10,30", "20,10,30 12,14,13,12 * * *") # TODO: sort
+  _("*-1/2-1,3 *:30", "30 * 1,3 1/2 *")
+  _("03-05 08:05", "05 08 05 03 *")
+  _("08:05:00", "05 08 * * *")
+  _("05:40", "40 05 * * *")
+  _("Sat,Sun 12-* 08:05", "05 08 * 12 0,6")
+  _("Sat,Sun 08:05", "05 08 * * 0,6")
+
+  def _(systemd):
+    self.assertRaises(Exception, systemd_to_cron, systemd)
+  _("test")
+  _("")
+  _("7")
+  _("121212:1:2")
+
+  _("Wed *-1")
+  _("08:05:40")
+  _("2003-03-05")
+
+  _("0-1"); _("13-1"); _("6/4-1"); _("5/8-1")
+  _("1-0"); _("1-32"); _("1-4/3"); _("1-14/18")
+  _("24:0");_("9/9:0"); _("8/16:0")
+  _("0:60"); _("0:22/22"); _("0:15/45")
+
+if __name__ == '__main__':
+  import unittest
+  unittest.TextTestRunner().run(type('', (unittest.TestCase,), {
+    'runTest': test})())