Open Stack

Hi Dmitry,

I can try to provide you description on what current Nailgun agent is, and
what are potential requirements we may need from HW discovery system.

Nailgun agent is a one-file Ruby script [0] which is periodically run under
cron. It collects information about HW using ohai [1], plus it does custom
parsing, filtration, retrieval of HW information. After the information is
collected, it is sent to Nailgun, that is how node gets discovered in Fuel.

To summarise entire process:
1. After Fuel master node is installed, user restarts the nodes and they
get booted via PXE with bootstrap image.
2. Inside of bootstrap image Nailgun agent is configured and installed.
3. Cron runs Nailgun agent.
3. Information is collected by Nailgun agent.
4. Information is sent to Nailgun.
5. Nailgun creates new node, for which user using UI can define
partitioning schema and networks allocation.
6. After that provisioning/deployment can be run.

Every time Nailgun agent sends a request, we submit information about the
time last request from agent was done, if there was no request for time N,
we mark the node as offline.

With current implementation we have several problems (not all of them
should be addressed by HW discovery system only):

1. A lot of things are hardcoded on the agent's side, which does additional
filtration based on pre-hardcoded parameters [2], the less hardcoded logic
in agent we have the easier it's to do upgrades and deliver fixes (upgrade
one service is simpler than hundreds of agents).

2. In order to get additional HW information user has to continue
hardcoding it right in Ruby code, as the result, there is no way for Fuel
plugin [3], to get additional hardware specific information, we need
data-driven mechanism to be able to describe, what/how/where information to
get from the node.

3. Hardware gets changed, we have cases when NICs, HDDs, Motherboards are
replaced/removed/added, as the result we should have a tool which would
allow us to see these changes and when they were performed, based on that
we want to be able to notify the user and provide suggestions how to
proceed with these changes.

4. With 3rd real-world cases, we have a problem of node identification,
when HW gets changed and automatic matching doesn't happen (when we cannot
say for sure that this is the node which we've already had), user should be
able to say, that new node X is in fact offline node Y.

5. Different source of HW information, we want to have a system which would
allow us to have hardware discovery from IPMI, CSV file, Cobbler, CMDB, etc
at the same time.

6. Not only hardware gets changed, but operating system (with kernel
versions), for example when we used CentOS as a bootstrap (in bootstrap we
do provisioning/partitioning + initial configuration) and Ubuntu for
running OpenStack, we were getting wide range of weird problems, from NICs
renaming to Disks' ids duplication and deduplication. There should be a way
to track these problems (3rd item), and we should be able to add operating
system specific system to get HW information.

7. Cron + Agent based mechanism to define if node is offline is not the
best, since it adds race conditions and in fact it only says if there is
connectivity between Nailgun and Nailgun agent.

Will be glad to answer any questions you have, if there are any.

Thanks,

[0] https://github.com/openstack/fuel-nailgun-agent/blob/master/agent
[1] https://docs.chef.io/ohai.html
[2]
https://github.com/openstack/fuel-nailgun-agent/blob/master/agent#L46-L51
[3] https://wiki.openstack.org/wiki/Fuel/Plugins


On Wed, Mar 16, 2016 at 1:39 PM, Dmitry Tantsur <dtantsur at redhat.com> wrote:

> On 03/15/2016 01:53 PM, Serge Kovaleff wrote:
>
>> Dear All,
>>
>> Let's compare functional abilities of both solutions.
>>
>> Till the recent Mitaka release Ironic-inspector had only Introspection
>> ability.
>>
>> Discovery part is proposed and implemented by Anton Arefiev. We should
>> align expectations and current and future functionality.
>>
>> Adding Tags to attract the Inspector community.
>>
>
> Hi!
>
> It would be great to see what we can do to fit the nailgun use case.
> Unfortunately, I don't know much about it right now. What are you missing?
>
>
>> Cheers,
>> Serge Kovaleff
>> http://www.mirantis.com <http://www.mirantis.com/>
>> cell: +38 (063) 83-155-70
>>
>> On Tue, Mar 15, 2016 at 2:07 PM, Alexander Saprykin
>> <asaprykin at mirantis.com <mailto:asaprykin at mirantis.com>> wrote:
>>
>>     Dear all,
>>
>>     Thank you for the opinions about this problem.
>>
>>     I would agree with Roman, that it is always better to reuse
>>     solutions than re-inventing the wheel. We should investigate
>>     possibility of using ironic-inspector and integrating it into fuel.
>>
>>     Best regards,
>>     Alexander Saprykin
>>
>>     2016-03-15 13:03 GMT+01:00 Sergii Golovatiuk
>>     <sgolovatiuk at mirantis.com <mailto:sgolovatiuk at mirantis.com>>:
>>
>>         My strong +1 to drop off nailgun-agent completely in favour of
>>         ironic-inspector. Even taking into consideration we'lll need to
>>         extend  ironic-inspector for fuel needs.
>>
>>         --
>>         Best regards,
>>         Sergii Golovatiuk,
>>         Skype #golserge
>>         IRC #holser
>>
>>         On Tue, Mar 15, 2016 at 11:06 AM, Roman Prykhodchenko
>>         <me at romcheg.me <mailto:me at romcheg.me>> wrote:
>>
>>             My opition on this is that we have too many re-invented
>>             wheels in Fuel and it’s better think about replacing them
>>             with something we can re-use than re-inventing them one more
>>             time.
>>
>>             Let’s take a look at Ironic and try to figure out how we can
>>             use its features for the same purpose.
>>
>>
>>             - romcheg
>>              > 15 бер. 2016 р. о 10:38 Neil Jerram
>>             <Neil.Jerram at metaswitch.com
>>             <mailto:Neil.Jerram at metaswitch.com>> написав(ла):
>>
>>              >
>>              > On 15/03/16 07:11, Vladimir Kozhukalov wrote:
>>              >> Alexander,
>>              >>
>>              >> We have many other places where use Ruby (astute, puppet
>>             custom types,
>>              >> etc.). I don't think it is a good reason to re-write
>>             something just
>>              >> because it is written in Ruby. You are right about
>>             tests, about plugins,
>>              >> but let's look around. Ironic community has already
>>             invented discovery
>>              >> component (btw written in python) and I can't see any
>>             reason why we
>>              >> should continue putting efforts in nailgun agent and not
>>             try to switch
>>              >> to ironic-inspector.
>>              >
>>              > +1 in general terms.  It's strange to me that there are
>>             so many
>>              > OpenStack deployment systems that each do each piece of
>>             the puzzle in
>>              > their own way (Fuel, Foreman, MAAS/Juju etc.) - and which
>>             also means
>>              > that I need substantial separate learning in order to use
>>             all these
>>              > systems.  It would be great to see some consolidation.
>>              >
>>              > Regards,
>>              >       Neil
>>              >
>>              >
>>              >
>>
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