<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body bgcolor="#ffffff" text="#000000"> I have been working on a cobbler dns zone factory trigger, which populates zone files according to a customizable regex-based hostname-ip-mapping setting. The trigger is very basic now and uses static settings. Essentially it <ul> <li>Checks to see whether the hostname is valid.</li> <ul> <li>This is done by means of a modifiable regex-based function.</li> </ul> <li>The hostname is converted to an IP address</li> <ul> <li>This is done by means of a modifiable regex-based function.</li> </ul> <li>Forward/Reverse DNS zone templates are cheetahfied and written to a zone directory. </li> </ul> Unfortunately, cobbler does two things that limit certain this kind of DNS trigger: <ol> <li>The 'syncing' occurs prior to the call of this trigger (and, I would gather, all triggers).</li> <ul> <li>This prohibits custom checks for a valid --name, among other arguments, before the actual sync should occur.</li> <ul> <li>Basically, the cobbler check that I've traced (as show below in the get_pxe_filename definition) determines whether the --name is a valid MAC address or IP address (the actual checking functions found in utils.py) OR whether the --name is a resolveable hostname.</li> </ul> <li>Custom checks are a good idea, because they promote moving policy to trigger-space. </li> </ul> <li>The check on 'resolveable hostnames'</li> <ul> <li>This prevents modifications to zone files in triggers.</li> <ul> <li>If the zone file(s) targeted for modification during the trigger mechanism do not possess name entries for the targeted systems (corresponding to system --name), cobbler will complain that --name does not resolve, and one receives an exception.</li> </ul> </ul> </ol> My problem is that, by (2) I cannot implement my trigger at all without modifying cobbler source code (to allow unresolvable names as argument for system adds). If I were to modify the source code accordingly, I find the deeper problem (1), where although my custom check may prohibit a certain kind of hostname from being added to DNS, the system is *still* added, since syncing occurs prior to the call to the trigger. This is an architectural question, which has strong bearing on the development of triggers, and a philosophical question as to whether policy ought to be pushed out to the triggers. What would the best short-term approach to resolving this problem be? I appreciate your time. --BEGIN action_sync.py SNIPPER-- def get_pxe_filename(self,name_input): """ The configuration file for each system pxe uses is either a form of the MAC address of the hex version of the IP. Not sure about ipv6 (or if that works). The system name in the config file is either a system name, an IP, or the MAC, so figure it out, resolve the host if needed, and return the pxe directory name. """ if name_input == "default": return "default" name = utils.find_system_identifier(name_input) if utils.is_ip(name): return utils.get_host_ip(name) elif utils.is_mac(name): return "01-" + "-".join(name.split(":")).lower() else: raise cexceptions.CobblerException("err_resolv", name) --END action_sync.py SNIPPET-- --Adam </body> </html>