[ClusterLabs] Antw: Re: Set a node attribute for multiple nodes with one command

[Ken Gaillot]

On 11/23/2016 11:27 AM, Kostiantyn Ponomarenko wrote:
> Maybe I am doing something wrong, but I cannot set "status" section node
> attributes to a shadow cib, cluster applies them immediately.
> To try it out I do in a console:
> 
>     crm_shadow --create test
>     crm_attribute --type nodes --node node-0 --name my-attribute
> --update 1 --lifetime=reboot
> 
> And this attribute is set to the live cluster configuration immediately.
> What am I doing wrong?

Strange ... if you use --lifetime=forever, it's recorded in the shadow
CIB, but if you use --lifetime=reboot, it's recorded in the live CIB.
That looks like a bug to me; I'll make a note to investigate.

> Thank you,
> Kostia
> 
> On Tue, Nov 22, 2016 at 11:33 PM, Kostiantyn Ponomarenko
> <konstantin.ponomarenko at gmail.com
> <mailto:konstantin.ponomarenko at gmail.com>> wrote:
> 
>     Ken,
>     Thank you for the explanation.
>     I will try this low-level way of shadow cib creation tomorrow.
>     PS: I will sleep much better with this excellent news/idea. =)
> 
>     Thank you,
>     Kostia
> 
>     On Tue, Nov 22, 2016 at 10:53 PM, Ken Gaillot <kgaillot at redhat.com
>     <mailto:kgaillot at redhat.com>> wrote:
> 
>         On 11/22/2016 04:39 AM, Kostiantyn Ponomarenko wrote:
>         > Using "shadow cib" in crmsh looks like a good idea, but it doesn't work
>         > with node attributes set into "status" section of Pacemaker config.
>         > I wonder it it is possible to make it work that way.
> 
>         Forgot to mention -- the shadow CIB is probably the best way to
>         do this.
>         I don't know if there's a way to do it in crmsh, but you can use
>         it with
>         the low-level commands crm_shadow and crm_attribute
>         --lifetime=reboot.
> 
>         > Ken,
>         >>> start dampening timer
>         > Could you please elaborate more on this. I don't get how I can set this
>         > timer.
>         > Do I need to set this timer for each node?
>         >
>         >
>         > Thank you,
>         > Kostia
>         >
>         > On Mon, Nov 21, 2016 at 9:30 AM, Ulrich Windl
>         > <Ulrich.Windl at rz.uni-regensburg.de
>         <mailto:Ulrich.Windl at rz.uni-regensburg.de>
>         > <mailto:Ulrich.Windl at rz.uni-regensburg.de
>         <mailto:Ulrich.Windl at rz.uni-regensburg.de>>> wrote:
>         >
>         >     >>> Ken Gaillot <kgaillot at redhat.com
>         <mailto:kgaillot at redhat.com> <mailto:kgaillot at redhat.com
>         <mailto:kgaillot at redhat.com>>>
>         >     schrieb am 18.11.2016 um 16:17 in Nachricht
>         >     <d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com
>         <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>
>         >     <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com
>         <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>>>:
>         >     > On 11/18/2016 08:55 AM, Kostiantyn Ponomarenko wrote:
>         >     >> Hi folks,
>         >     >>
>         >     >> Is there a way to set a node attribute to the "status"
>         section for few
>         >     >> nodes at the same time?
>         >     >>
>         >     >> In my case there is a node attribute which allows some
>         resources to
>         >     >> start in the cluster if it is set.
>         >     >> If I set this node attribute for say two nodes in a way
>         - one and then
>         >     >> another, than these resources are not distributed
>         equally between these
>         >     >> two nodes. That because Pacemaker picks the first node
>         to with this
>         >     >> attribute is set and immediately starts all allowed
>         resources on it. And
>         >     >> this is not the behavior i would like to get.
>         >     >>
>         >     >> Thank you,
>         >     >> Kostia
>         >     >
>         >     > Not that I know of, but it would be a good feature to add to
>         >     > attrd_updater and/or crm_attribute.
>         >
>         >     With crm (shell) you don't have transactions for node
>         attributes,
>         >     but for the configuration. So if you add a location
>         restriction
>         >     preventing any resources on your nodes, then enable the
>         nodes, and
>         >     then delete the location restrictions in one transaction,
>         you might
>         >     get what you want. It's not elegant, but itt ill do.
>         >
>         >     To the crm shell maintainer: Is is difficult to build
>         transactions
>         >     to node status changes? The problem I see is this: For
>         configuration
>         >     you always have transactions (requiring "commit), but for
>         nodes you
>         >     traditionally have non (effects are immediate). So you'd
>         need a
>         >     thing like "start transaction" which requires a "commit"
>         or some
>         >     kind of abort later.
>         >
>         >     I also don't know whether a "shadow CIB" would help for
>         the original
>         >     problem.
>         >
>         >     Ulrich
>         >
>         >     >
>         >     > You can probably hack it with a dampening value of a few
>         seconds. If
>         >     > your rule checks for a particular value of the
>         attribute, set all the
>         >     > nodes to a different value first, which will write that
>         value and
>         >     start
>         >     > the dampening timer. Then set all the attributes to the
>         desired value,
>         >     > and they will get written out together when the timer
>         expires.