[ClusterLabs] Determine a resource's current host in the CIB

[Digimer]

On 2020-09-24 3:19 a.m., Reid Wahl wrote:
> **Directly via the CIB**, I don't see a more obvious way than looking
> for the most recent (perhaps by last-rc-change) successful
> (rc-code="0" or rc-code="8") monitor operation. That might be
> error-prone. I haven't looked into exactly how crm_simulate parses
> resource status from the CIB XML yet. Others on the list might know.
> 
> Is there a particular reason why you need to parse the status directly
> from the CIB, as opposed to using other tools? Does your use case
> allow you to use crm_simulate with the cib.xml as input? (e.g.,
> `crm_simulate --xml-file=<cibfile>`)

I'm writing a parser for our next HA platform, and XML is a lot more
machine-parsable that output meant for human consumption. Also, adding a
layer between the data and the processor seems like an avoidable failure
point (ie: what if crm_mon output changes format and breaks the regex
used to pull data).

Programs like crm_mon and pcs have a way of determining what is running
where, and that's fundamentally what I am trying to do as well.

digimer

> On Wed, Sep 23, 2020 at 11:04 PM Digimer <lists at alteeve.ca> wrote:
>>
>> Hi all,
>>
>>   I'm trying to parse the CIB to determine which node a given resource
>> (VM) is currently running on. I notice that the 'monitor' shows in both
>> node's status element (from when it last ran when the node previously
>> hosted the resource).
>>
>> https://pastebin.com/6RCMWdgq
>>
>> Specifically, I see under node 1 (the active host when the CIB was read):
>>
>> <lrm_rsc_op id="srv07-el6_monitor_60000"
>> operation_key="srv07-el6_monitor_60000" operation="monitor"
>> crm-debug-origin="do_update_resource" crm_feature_set="3.3.0"
>> transition-key="23:85:0:829209fd-35f2-4626-a9cd-f8a50a62871e"
>> transition-magic="0:0;23:85:0:829209fd-35f2-4626-a9cd-f8a50a62871e"
>> exit-reason="" on_node="mk-a02n01" call-id="76" rc-code="0"
>> op-status="0" interval="60000" last-rc-change="1600925201"
>> exec-time="541" queue-time="0"
>> op-digest="65d0f0c9227f2593835f5de6c9cb9d0e"/>
>>
>> And under node 2 (hosted the server in the past):
>>
>> <lrm_rsc_op id="srv07-el6_monitor_60000"
>> operation_key="srv07-el6_monitor_60000" operation="monitor"
>> crm-debug-origin="do_update_resource" crm_feature_set="3.3.0"
>> transition-key="23:83:0:829209fd-35f2-4626-a9cd-f8a50a62871e"
>> transition-magic="0:0;23:83:0:829209fd-35f2-4626-a9cd-f8a50a62871e"
>> exit-reason="" on_node="mk-a02n02" call-id="61" rc-code="0"
>> op-status="0" interval="60000" last-rc-change="1600925173"
>> exec-time="539" queue-time="0"
>> op-digest="65d0f0c9227f2593835f5de6c9cb9d0e"/>
>>
>> I don't see any specific entry in the CIB saying "resource X is
>> currently hosted on node Y", so I assume I should infer which node is
>> the current host? If so, should I look at which node's 'exec-time' is
>> higher, or which node has the higher 'call-id'?
>>
>> Or am I missing a more obvious way to tell what resource is running on
>> which node?
>>
>> --
>> Digimer
>> Papers and Projects: https://alteeve.com/w/
>> "I am, somehow, less interested in the weight and convolutions of
>> Einstein’s brain than in the near certainty that people of equal talent
>> have lived and died in cotton fields and sweatshops." - Stephen Jay Gould
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> 
> 
> 


-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould