[ClusterLabs] pcs stonith update <id> <args> problems

[Digimer]

On 2021-07-21 8:19 a.m., Tomas Jelinek wrote:
> Dne 16. 07. 21 v 16:30 Digimer napsal(a):
>> On 2021-07-16 9:26 a.m., Tomas Jelinek wrote:
>>> Dne 16. 07. 21 v 6:35 Andrei Borzenkov napsal(a):
>>>> On 16.07.2021 01:02, Digimer wrote:
>>>>> Hi all,
>>>>>
>>>>>     I've got a predicament... I want to update a stonith resource to
>>>>> remove an argument. Specifically, when resource move nodes, I want to
>>>>> change the stonith delay to favour the new host. This involves adding
>>>>> the 'delay="x"' argument to one stonith resource, and removing it from
>>>>> the other;
>>>>>
>>>>> Example;
>>>>>
>>>>> ====
>>>>> # pcs cluster cib | grep -B7 -A7 '"delay"'
>>>>>         <primitive class="stonith" id="ipmilan_node1"
>>>>> type="fence_ipmilan">
>>>>>           <instance_attributes id="ipmilan_node1-instance_attributes">
>>>>>             <nvpair id="ipmilan_node1-instance_attributes-ipaddr"
>>>>> name="ipaddr" value="10.201.17.1"/>
>>>>>             <nvpair id="ipmilan_node1-instance_attributes-password"
>>>>> name="password" value="xxx"/>
>>>>>             <nvpair
>>>>> id="ipmilan_node1-instance_attributes-pcmk_host_list"
>>>>> name="pcmk_host_list" value="an-a02n01"/>
>>>>>             <nvpair id="ipmilan_node1-instance_attributes-username"
>>>>> name="username" value="admin"/>
>>>>>             <nvpair id="ipmilan_node1-instance_attributes-delay"
>>>>> name="delay" value="15"/>
>>>>>           </instance_attributes>
>>>>>           <operations>
>>>>>             <op id="ipmilan_node1-monitor-interval-60" interval="60"
>>>>> name="monitor"/>
>>>>>           </operations>
>>>>>         </primitive>
>>>>> ====
>>>>>
>>>>> Here, the stonith resource 'ipmilan_node1' has the delay="15".
>>>>>
>>>>> If I run:
>>>>>
>>>>> ====
>>>>> # pcs stonith update ipmilan_node1 fence_ipmilan ipaddr="10.201.17.1"
>>>>> password="xxx" username="admin"; echo $?
>>>>> 0
>>>>> ====
>>>>>
>>>>> I see nothing happen in journald, and the delay argument remains in
>>>>> the
>>>>> 'pcs cluster cib' output. If, however, I do;
>>>>>
>>>>> ====
>>>>> # /usr/sbin/pcs stonith update ipmilan_node1 fence_ipmilan
>>>>> ipaddr="10.201.17.1" password="xxx" username="admin" delay="0";
>>>>> echo $?
>>>>> 0
>>>>> ====
>>>>>
>>>>> I can see in journald that the CIB was updated and can confirm in 'pcs
>>>>> cluster cib' that the 'delay' value becomes '0'. So it seems that,
>>>>> if an
>>>>> argument previously existed and is NOT specified in an update, it
>>>>> is not
>>>>> removed.
>>>>>
>>>>> Is this intentional for some reason? If so, how would I remove the
>>>>> delay
>>>>> attribute?
>>>
>>> Yes, this is intentional. As far as I remember, update commands in pcs
>>> have always worked this way:
>>> * do not change attributes not specified in the command
>>> * if an attribute is specified with an empty value, remove the attribute
>>> from cluster configuration
>>> * else set specified value of the specified attribute in cluster
>>> configuration
>>>
>>> This means you only need to specify attributes you want to change. You
>>> don't need to bother with attributes you want to keep unchanged.
>>>
>>> If you want to delete the delay attribute, you can do it like this:
>>> pcs stonith update ipmilan_node1 delay=
>>> This will remove delay and keep all the other attributes unchanged.
>>>
>>> I'm not sure why this principle is not documented in pcs man page. We
>>> can fix that, though.
>>>
>>> Note that specifying a stonith agent in the update command does nothing
>>> (which is expected) and is silently ignored by pcs (which is a bug).
>>>
>>> Regards,
>>> Tomas
>>
>> Ah, thank you (and as Andrei)!
>>
>> Is this behaviour not documented in 'pcs stonith help' -> update? Or was
>> I blind and missed it?
>>
> 
> I think this isn't documented anywhere in pcs. It may be described in
> Clusters from Scratch or a similar document. I think I've read it
> somewhere, but I'm not sure where it was.
> 
> Anyway, I put it on our todo list to get it explained in pcs help and
> man page.
> 
> 
> Thanks,
> Tomas

Thanks!

-- 
Digimer
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