On May 22, 7:24 pm, Sean Millichamp <[email protected]> wrote:
> On Mon, 2012-05-21 at 15:39 -0600, Deepak Giridharagopal wrote:
> > 1) The data stored in PuppetDB is entirely driven by puppetmasters
> > compiling catalogs for agents. If your entire database exploded and
> > lost all data, everything will be 100% repopulated within around
> > $runinterval minutes.
>
> I think that this is a somewhat dangerous line of thinking.  Please
> correct me if my understanding of storedconfigs are wrong, but if I am
> managing a resource with resources { 'type': purge => true } (or a
> purged directory populated file resources) and any subset of those
> resources are exported resources then, if my "entire database exploded",
> would I not have Puppet purging resources that haven't repopulated
> during this repopulation time?  They would obviously be replaced, but if
> those were critical resources (think exported Nagios configs, /etc/hosts
> entries, or the like) then this could be a really big problem.


That understanding of storeconfigs looks right, but I think the
criticism is misplaced.  It is not Deepak's line of thinking that is
dangerous, but rather the posited strategy of purging (un)collected
resources.  Indeed, I rate resource purging as a bit dangerous *any*
way you do it.  Moreover, the consequences of a storeconfig DB blowing
up are roughly the same regardless of the DBMS managing it or the
middleware between it an the Puppetmaster.  I don't see how the
existence of that scenario makes PuppetDB any better or worse.


> To me storedconfigs are one of the killer features in Puppet. We are
> using them for a handful of critical things and I plan to only expand
> their use. I'm glad that Puppet Labs is focusing some attention on them,
> but this attitude of we can wait out a repopulation has me worried.


If you cannot afford to wait out a repopulation of some resource, then
you probably should not risk purging its resource type.  If you do not
purge, then a storeconfig implosion just leaves your resources
unmanaged.  If you choose to purge anyway then you need to understand
that you thereby assume some risk in exchange for convenience;
mitigating that risk probably requires additional effort elsewhere
(e.g. DB replication and failover, backup data center, ...).


John

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