I spoke with Michael somewhat on IRC regarding my desire to implement a
DNS zone-related trigger mechanism. My main problem was that cobbler
"core" (as opposed to "triggers") enforced a policy on trigger
writers. When adding a new system (generically speaking, "cobbler
system add --name=<ip│mac│hostname | default>
--profile="" where --name=hostname, and hostname !=
<resolveable hostname>, cobbler prevents the system addition.
This presented much difficulty in adding zone entries to systems that
didn't yet exist in DNS (chicken and egg). If that were not enough
trouble, if I would then remove the checking mechanism (as seen in
action_sync.py:get_pxe_filename() method), the sync occurs regardless
whether my own 'valid hostname' checks could be utilized.
I asked Michael if there were a way to push such policy mechanisms
(there really is only one -- the system.name check) to the trigger
writers, so I might have a way to enforce my checks. Rather than to
rewrite the control of the add method (whose utility outweighs its
rarely-seen limitations), Michael recommended some options including
the solution I'm offering.
With the following minor patch and the addition of
../trigger/system/{add,remove}/{pre,post} directories, triggers that
either make use of custom checks (which conflict with those in
get_pxe_filename()) and/or need to be executed prior to syncs, can then
be placed in the .../pre/... directories. Those triggers which may be
executed without these requirements can be placed in the .../post/...
directories.
I am able to refer to "sys.argv[1]" within my trigger, and this will
refer to the --name. Then, I can make use of --name within my
pre_trigger and perform custom checks, dns zone instantiation, etc.
before returning control to cobbler core, where the core name checks
are then performed. Normal triggers would be called after sync as they
currently are, but they are to be found in the .../post/... directory.
There are other ways of implementing the mechanism. Perhaps only one
trigger directory is needed with checked filename prefixes or suffixes
for pre/post. I am only following the existing mechanism in adding the
directories. If there are more elegant or efficient mechanisms, it
will likely be part of a complete trigger system rehaul, as Michael has
alluded to...
If you would like to use this patch, you will have to rebuild with the following changes to the specfile and setup.py:
--- cobbler.spec.orig 2007-04-26 22:03:04.000000000 +0000
+++ cobbler.spec 2007-06-04 23:35:23.000000000 +0000
@@ -105,14 +105,22 @@
%dir /var/log/cobbler/syslog
%defattr(2550,root,root)
%dir /var/lib/cobbler
-%dir /var/lib/cobbler/triggers/add/distro
-%dir /var/lib/cobbler/triggers/add/profile
-%dir /var/lib/cobbler/triggers/add/system
-%dir /var/lib/cobbler/triggers/add/repo
-%dir /var/lib/cobbler/triggers/delete/distro
-%dir /var/lib/cobbler/triggers/delete/profile
-%dir /var/lib/cobbler/triggers/delete/system
-%dir /var/lib/cobbler/triggers/delete/repo
+%dir /var/lib/cobbler/triggers/add/distro/pre
+%dir /var/lib/cobbler/triggers/add/distro/post
+%dir /var/lib/cobbler/triggers/add/profile/pre
+%dir /var/lib/cobbler/triggers/add/profile/post
+%dir /var/lib/cobbler/triggers/add/system/pre
+%dir /var/lib/cobbler/triggers/add/system/post
+%dir /var/lib/cobbler/triggers/add/repo/pre
+%dir /var/lib/cobbler/triggers/add/repo/post
+%dir /var/lib/cobbler/triggers/delete/distro/pre
+%dir /var/lib/cobbler/triggers/delete/distro/post
+%dir /var/lib/cobbler/triggers/delete/profile/pre
+%dir /var/lib/cobbler/triggers/delete/profile/post
+%dir /var/lib/cobbler/triggers/delete/system/pre
+%dir /var/lib/cobbler/triggers/delete/system/post
+%dir /var/lib/cobbler/triggers/delete/repo/pre
+%dir /var/lib/cobbler/triggers/delete/repo/post
/var/lib/cobbler/elilo-3.6-ia64.efi
/var/lib/cobbler/menu.c32
%defattr(-,root,root)
--- setup.py.orig 2007-04-26 18:03:12.000000000 -0400
+++ setup.py 2007-06-04 22:05:22.000000000 -0400
@@ -78,14 +78,22 @@
(vw_links, []),
(tftp_cfg, []),
(tftp_images, []),
- ("/var/lib/cobbler/triggers/add/distro", []),
- ("/var/lib/cobbler/triggers/add/profile", []),
- ("/var/lib/cobbler/triggers/add/system", []),
- ("/var/lib/cobbler/triggers/add/repo", []),
- ("/var/lib/cobbler/triggers/delete/distro", []),
- ("/var/lib/cobbler/triggers/delete/profile", []),
- ("/var/lib/cobbler/triggers/delete/system", []),
- ("/var/lib/cobbler/triggers/delete/repo", [])
+ ("/var/lib/cobbler/triggers/add/distro/pre", []),
+ ("/var/lib/cobbler/triggers/add/distro/post", []),
+ ("/var/lib/cobbler/triggers/add/profile/pre", []),
+ ("/var/lib/cobbler/triggers/add/profile/post", []),
+ ("/var/lib/cobbler/triggers/add/system/pre", []),
+ ("/var/lib/cobbler/triggers/add/system/post", []),
+ ("/var/lib/cobbler/triggers/add/repo/pre", []),
+ ("/var/lib/cobbler/triggers/add/repo/post", []),
+ ("/var/lib/cobbler/triggers/delete/distro/pre", []),
+ ("/var/lib/cobbler/triggers/delete/distro/post", []),
+ ("/var/lib/cobbler/triggers/delete/profile/pre", []),
+ ("/var/lib/cobbler/triggers/delete/profile/post", []),
+ ("/var/lib/cobbler/triggers/delete/system/pre", []),
+ ("/var/lib/cobbler/triggers/delete/system/post", []),
+ ("/var/lib/cobbler/triggers/delete/repo/pre", [])
+ ("/var/lib/cobbler/triggers/delete/repo/post", [])
],
description = SHORT_DESC,
long_description = LONG_DESC
The actual core patches are listed below
--- cobbler/collection_distros.py.orig 2007-04-16 15:57:29.000000000 -0400
+++ cobbler/collection_distros.py 2007-06-04 21:38:33.000000000 -0400
@@ -51,9 +51,10 @@
raise cexceptions.CobblerException("orphan_profile",v.name)
if self.find(name):
if with_delete:
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/distro/pre/*")
lite_sync = action_litesync.BootLiteSync(self.config)
lite_sync.remove_single_profile(name)
- self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/distro/*")
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/distro/post/*")
del self.listing[name]
return True
raise cexceptions.CobblerException("delete_nothing")
--- cobbler/collection_profiles.py.orig 2007-04-16 15:07:37.000000000 -0400
+++ cobbler/collection_profiles.py 2007-06-04 21:39:01.000000000 -0400
@@ -48,9 +48,10 @@
raise cexceptions.CobblerException("orphan_system",v.name)
if self.find(name):
if with_delete:
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/profile/pre/*")
lite_sync = action_litesync.BootLiteSync(self.config)
lite_sync.remove_single_profile(name)
- self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/profile/*")
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/profile/post/*")
del self.listing[name]
return True
raise cexceptions.CobblerException("delete_nothing")
--- cobbler/collection_systems.py.orig 2007-04-16 15:07:47.000000000 -0400
+++ cobbler/collection_systems.py 2007-06-04 21:41:11.000000000 -0400
@@ -49,9 +49,10 @@
"""
if self.find(name):
if with_delete:
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/system/pre/*")
lite_sync = action_litesync.BootLiteSync(self.config)
lite_sync.remove_single_system(name)
- self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/system/*")
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/system/post/*")
del self.listing[name]
return True
raise cexceptions.CobblerException("delete_nothing")
--- cobbler/collection_repos.py.orig 2007-04-20 18:54:24.000000000 -0400
+++ cobbler/collection_repos.py 2007-06-04 21:40:25.000000000 -0400
@@ -52,8 +52,9 @@
# but is left in for consistancy in the API.
if self.find(name):
- self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/repo/*")
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/repo/pre/*")
del self.listing[name]
+ self._run_triggers(self.listing[name], "/var/lib/cobbler/triggers/delete/repo/post/*")
return True
raise cexceptions.CobblerException("delete_nothing")
--- cobbler/collection.py.orig 2007-04-20 16:14:52.000000000 -0400
+++ cobbler/collection.py 2007-06-04 21:35:46.000000000 -0400
@@ -91,6 +91,7 @@
# perform filesystem operations
if with_copy:
+ self._run_triggers(ref,"/var/lib/cobbler/triggers/add/%s/pre/*" % self.collection_type())
lite_sync = action_litesync.BootLiteSync(self.config)
if isinstance(ref, item_system.System):
lite_sync.add_single_system(ref.name)
@@ -103,8 +104,8 @@
# save the tree, so if neccessary, scripts can examine it.
self.config.api.serialize()
-
- self._run_triggers(ref,"/var/lib/cobbler/triggers/add/%s/*" % self.collection_type())
+
+ self._run_triggers(ref,"/var/lib/cobbler/triggers/add/%s/post/*" % self.collection_type())
return True
--Adam.
