Re: [munin-users] Refuses to graph due to missing RRD ... that should not exist ...

[DoubleHP <dou...@do...>]

On 25/11/16 02:54, Lars Kruse wrote:
> Hi,
> 
> 
> Am Thu, 24 Nov 2016 11:27:03 +0100
> schrieb DoubleHP <dou...@do...>:
> 
>> On 23/11/16 05:18, Lars Kruse wrote:
>>> Wild guessing: did you try to change the name of the field ("adps")?
>>>
>>> In order to help reproducing this issue: could you send us a valid example
>>> output of your plugin?  
>>
>> I have spent hours on dichotomy ... and I confirm the idea I had years
>> ago; bug occurs in multigraph, for parent graph, when a subgraph contains
>> a field with the name of the subgraph itself.
> 
> It is great, that you found the critical detail!
> 
> Could you please open a bug report for this issue?

I was wrong:

2017/01/29 20:22:49 [RRD ERROR] Unable to graph
/var/cache/munin/www/doublehp.org/rpi-08.doublehp.org/edf_teleinformation_locataire42dtagedroit-week.png
: opening
'/var/lib/munin/doublehp.org/rpi-08.doublehp.org-edf_teleinformation_locataire42dtagedroit-adps-g.rrd':
No such file or directory
2017/01/29 20:22:49 [RRD ERROR] rrdtool 'graph'
'/var/cache/munin/www/doublehp.org/rpi-08.doublehp.org/edf_teleinformation_locataire42dtagedroit-week.png'
\

The problem is still on parent image, but for a different reason:


edf_teleinformation_locataire42dtagedroit-week.png
is parent image for the multigraph, and it can't be drawn because some
field is missing; here is the code for config:

                echo "multigraph ${sshh}_${!myuserstring}"
                echo "graph_title EDF TIC for ${myuser}"
                echo "graph_category edf"
                echo "graph_args --base 1000"
                echo "graph_vtitle vtitle"
                echo "graph_vlabel vlabel"
                echo "graph_info Numero de serie du compteur: $ADCO . Port
serie sur rPi: $SERIAL ."
                echo "pappavg.label PAPP"
                echo "pappavg.info Puissance apparente totale en W (compteur)"

and the plugin never sent usefull data for pappavg.value; I am not
surprised the line can't be graphed, but, there are still two bugs here:

1: munin should be able to graph an empty graph (with no field)

2: the reason should be about missing pappavg.rrd, not about adps.rrd.

I know the multigraph never sent any ADPS value; but adps field is not
listed in the config for main graph. So, error message reports wrong
missing RRD.

I can not report this to BTS, because:
- I don't understand the bug
- I don't have repro case
- I don't have fix
- I can't provide dumps for config and fetch (values are read in a real
time DB; calling munin-run, or doing manual fetch out of due time will
break things. I think trunk plugin may have similar problems: try to run a
loggrep plugin, called by two masters, I think one master will show
inapropriate values, especially around logrotates).

I will update my plugin to fix this weakness, but it may take months.

-- 
 >o_/ DEMAINE Benoît-Pierre (aka DoubleHP) http://benoit.demaine.info/
If computing were an exact science, IT engineers would'nt have work \_o<

"So all that's left, Is the proof that love's not only blind but deaf."
(FAKE TALES OF SAN FRANCISCO, Arctic Monkeys)