On Thu, Feb 24, 2011 at 10:49:27AM -0500, David McCurley wrote: > Thanks for the quick reply and especially the link. It was much better and > more thorough in testing than the other shell ra ldap link I found. > > > That would be the first python RA. BTW, there was recently posted > > slapd RA (implemented in shell), which I should review, but > > haven't done that yet. /At any rate, that RA does not support > > multi-state resources which I think would be essential. Did you > > plan to do that? At any rate, I'd suggest that you check that > > code too and then see if you need to do your own implementation. > > The thread starts here: > > > > http://marc.info/?l=linux-ha-dev&m=129666245428850&w=2 > > Great stuff and very thorough. But it doesn't look like it will work in our > config because the files won't exist on the DRBD slave. I will use this as > my new example. > > I'm not sure what you are referring to with "multi-state" resources. Is this > in relation to "promote,demote, migrate_to, migrate_from" in the guide, i.e. > master vs slave or is there more to it? I plan to support a master and slave > later on down the road -- under pressure to get this rolled out now. Is > there a good discussion / resource other than the dev guide? I had planned > to try to wade through the DRBD RA scripts to figure it out.
migrate_to/from are for something else. It's just promote (slave->master) and demote (master->slave). > Why python? Because shell is harder for me to read and I have to make a good > clear verbose example for some others who will also be doing some RA's (in > python) for our custom apps. No problem with python. Actually, there was an idea to provide a python class (RA or so) which would make implementing resource agents easier. > > > The config file for OpenLDAP is stored in > > > /etc/ldap/slapd.d/cn=config.ldif. This is on a DRBD > > > active-passive system and the /etc/ldap directory is actually a > > > symlink to the DRBD controlled share /vcoreshare/etc/ldap. The > > > real config file is at > > > /vcoreshare/etc/ldap/slapd.d/cn=config.ldif. > > > > What about the old style configuration? I assume that there are > > still quite a few installations/distributions using those. > > Yes, I have some code for that, using the example slapd init script and the > other examples I found, but no test environment for that. IIRC, the old configuration style is quite easy to parse. > > > So I'm trying to be very judicious with every function and > > > validation, checking file permissions, etc. But the problem is > > > that /etc/ldap/slapd.d/cn=config.ldif is only present on the > > > active DRBD node. My validate function checks that the file is > > > readable by the user/group that slapd is to run as. Now, as soon > > > as I start ldap in the cluster, it starts fine, but validate fails > > > on the standby node (because the DRBD volume isn't mounted) and > > > crm_mon shows a failed action: > > > > On probes (monitor with interval 0), some parts of validation > > which concern the local node and not the configuration should say > > OCF_NOT_RUNNING instead of error. This is exactly that case. No > > worries, because if the next action is start validation is > > invoked again. Probes are issued by pacemaker to establish if the > > resource is running and normally it is expected to be not running > > (for instance on node startup). > > Ah! I have a function that checks for probes but wasn't using it because I > didn't quite understand the semantics. OK, hope that it's clear now. Thanks, Dejan > > Very helpful stuff, thanks! > > _______________________________________________ > Pacemaker mailing list: Pacemaker@oss.clusterlabs.org > http://oss.clusterlabs.org/mailman/listinfo/pacemaker > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: > http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker _______________________________________________ Pacemaker mailing list: Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
