Open Stack

On 28/05/15 10:54, Richard Raseley wrote:
> Zane Bitter wrote:
>> Steve is working on a patch to allow package-based updates of overcloud
>> nodes[1] using the distro's package manager (yum in the case of RDO, but
>> conceivable apt in others). Note we're talking exclusively about minor
>> updates, not version-to-version upgrades here.
>>
>> Dan mentioned at the summit that this approach fails to take into
>> account the complex ballet of service restarts required to update
>> OpenStack services. (/me shakes fist at OpenStack services.) And
>> furthermore, that the Puppet manifests already encode the necessary
>> relationships to do this properly. (Thanks Puppeteers!) Indeed we'd be
>> doing the Wrong Thing by Puppet if we changed this stuff from under it.
>>
>> The problem of course is that neither Puppet nor yum/apt has a view of
>> the entire system. Yum doesn't know about the relationships between
>> services and Puppet doesn't know about all of the _other_ packages that
>> they depend on.
>>
>> One solution proposed was to do a yum update first but specifically
>> exclude any packages that Puppet knows about (the --excludes flag
>> appears sufficient for this); then follow that up with another Puppet
>> run using ensure -> latest.
>>
My only concern with this approach is how do we collect and maintain the 
excludes list. Other than that it sounds reasonable.
>> A problem with that approach is that it still fails to restart services
>> which have had libraries updated but have not themselves been updated.
>> That's no worse than the pure yum approach though. We might need an
>> additional way to just manually trigger a restart of services.

Maybe this could be handled at the packaging stage by reving the package 
version when there is a known fix in a low-level library, thus 
triggering a service restart in the puppet phase.