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From Aled Sage <aled.s...@gmail.com>
Subject Re: Trouble with YAML Transformer
Date Thu, 23 Mar 2017 13:15:09 GMT
Hi Graham,

I think that is non-deterministic: it failed approx 50% of the time in 
my simple unit test.

As described in BROOKLYN-458, the problem is that it will evaluate the 
expression when the sensor "cluster.first.entity" is set. It will 
immediately look up the "host.name" of that entity. If that sensor is 
aleady set, then great. If it is not yet set, it will return immediately 
without setting "cluster_first_host". Nothing will subsequently trigger 
the transformer again (because "clustere.first.entity" does not change), 
until Brooklyn is restarted or the first.entity is replaced.

There is a workaround suggested in BROOKLYN-458 that uses 
"triggerSensors" (and an extra aggregated sensor!) to ensure that the 
value is re-evaluated when the entity gets its host.name.

Aled

p.s. if you deploy this to a location where it takes a while for 
"host.name" to become available and thus populated (e.g. where it 
requires provisioning VMs), then it's much more likely to fail. If that 
is working for you consistently then let me know as I'd be interested to 
find out why!


On 23/03/2017 13:07, Graham Ashby wrote:
> Thanks all for all your help.
>
> For the record, what finally worked is:
>
>        - type: org.apache.brooklyn.enricher.stock.Transformer
>          brooklyn.config:
>            enricher.sourceSensor: $brooklyn:sensor("cluster.first.entity")
>            enricher.targetSensor: $brooklyn:sensor("cluster_first_host")
>            enricher.targetValue:
> $brooklyn:entity($brooklyn:attributeWhenReady("cluster.first.entity")).attributeWhenReady("host.name")
>
> Graham
>
>
>
> From:   Aled Sage <aled.sage@gmail.com>
> To:     dev@brooklyn.apache.org
> Date:   03/23/2017 07:47 AM
> Subject:        Re: Trouble with YAML Transformer
>
>
>
> Hi Graham, Mike, all,
>
> Graham: for why your transformer isn't populating the sensor value, see
> the explanation I've written up at
> https://issues.apache.org/jira/browse/BROOKLYN-458.
>
> For a workaround, see my first comment on that jira issue:
>
>      
> https://issues.apache.org/jira/browse/BROOKLYN-458?focusedCommentId=15938141&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15938141
>
>
>
> ---
> For the single-arg `$brooklyn:sensor(...)`...
>
> `$brooklyn:sensor("cluster.first.entity")` returns a new
> `AttributeSensor<Object>` instance, with name "cluster.first.entity". It
> doesn't look up the actual value of the sensor on the entity.
>
> What it means by "the given sensor on the current entity if found" is
> that: if the entity declares a strongly typed sensor with exactly that
> name (e.g. that also has a description and/or a type that is not
> Object), then it will be the entity's own sensor instance returned
> rather than constructing a new instance.
>
> ---
> Mike: as discussed with you offline, the error for:
>
>   $brooklyn:sensor("cluster.first.entity").attributeWhenReady("host.name")
>
> is reported at https://issues.apache.org/jira/browse/BROOKLYN-454, along
> with a workaround.
>
> The workaround is to use:
>
>   
> $brooklyn:entity($brooklyn:sensor("cluster.first.entity")).attributeWhenReady("host.name")
>
> ---
> For the record, Mike also hit
> https://issues.apache.org/jira/browse/BROOKLYN-457 while exploring
> possible solutions for Graham's use-case.
>
> ---
> Mike, could you please see what Brooklyn docs we can improve to make
> this clearer, and easier to use/understand? Also what should we improve
> to make investigating/debugging such problems easier?
>
> Aled
>
>
> On 22/03/2017 20:52, Graham Ashby wrote:
>> And if I try:
>>
>>             enricher.targetValue:
>> $brooklyn:sensor("cluster.first.entity").attributeWhenReady("host.name")
>>
>> I get the error:
>>
>> Error evaluating node (rethrowing)
>>
> '$brooklyn:sensor("cluster.first.entity").attributeWhenReady("host.name")':
>> java.lang.IllegalArgumentException: No such function
> 'attributeWhenReady'
>> on sensor("cluster.first.entity")
>>
>>
>>
>> From:   Mike Zaccardo <mike.zaccardo@cloudsoftcorp.com>
>> To:     dev@brooklyn.apache.org
>> Date:   03/22/2017 04:31 PM
>> Subject:        Re: Trouble with YAML Transformer
>>
>>
>>
>>   From the DSL spec [
>>
> https://docs.cloudsoft.io/blueprints/syntax-yaml-reference.html#dsl-commands
>
>> ]:
>>
>> * $brooklyn:sensor("sensor.name") returns the given sensor on the
> current
>> entity if found, or an untyped (Object) sensor;
>>
>> * $brooklyn:sensor("com.acme.brooklyn.ContainingEntityClass",
>> "sensor.name")
>> returns the strongly typed sensor defined in the given class
>>
>> Based on that, it seemed to me that the first, single-argument value
> would
>> actually return the value of the sensor (the "object"), not the sensor
>> construct itself (the "class").  However, I tried updating your code and
>> ended up with an empty-valued sensor.
>>
>>         brooklyn.enrichers:
>>           - type: org.apache.brooklyn.enricher.stock.Transformer
>>             brooklyn.config:
>>               enricher.sourceSensor:
>> $brooklyn:sensor("cluster.first.entity")
>>               enricher.targetSensor:
> $brooklyn:sensor("cluster_first_host")
>>               enricher.targetValue:
>>                 $brooklyn:formatString:
>>                 - "%s"
>>                 -
>> $brooklyn:sensor("cluster.first.entity").attributeWhenReady("host.name")
>>
>> I'd like to kick the question to the rest of the community -- why does
>> that
>> ^ end up with an empty value? It should default to searching the current
>> entity, which is a `DynamicCluster`, which has a `cluster.first.entity`.
>>
>> -Mike
>>
>> On Wed, Mar 22, 2017 at 12:52 PM Graham Ashby <Graham.Ashby@ca.ibm.com>
>> wrote:
>>
>> OK, Stupid mistake.
>> So, when I changed it to colon, I got the error:
>> 2017-03-22 15:41:43,612 WARN  o.a.b.c.b.s.d.BrooklynDslInterpreter
>> [brooklyn-jetty-server-8081-qtp434786215-42]: Error evaluating node
>> (rethrowing) '$brooklyn:sensor("org.apache.brooklyn.api.entity.Entity",
>> "cluster.first.entity").attributeWhenReady("host.name")':
>> org.apache.brooklyn.util.exceptions.PropagatedRuntimeException: Sensor
>> cluster.first.entity not found on class
>> org.apache.brooklyn.api.entity.Entity
>>
>> So I changed the Cast:
>>
>>             enricher.targetValue:
>> $brooklyn:sensor("org.apache.brooklyn.entity.group.AbstractGroup",
>> "cluster.first.entity").attributeWhenReady("host.name")
>>
>> Now I get:
>>
>> 2017-03-22 15:43:50,909 WARN  o.a.b.c.b.s.d.BrooklynDslInterpreter
>> [brooklyn-jetty-server-8081-qtp434786215-2217]: Error evaluating node
>> (rethrowing)
>> '$brooklyn:sensor("org.apache.brooklyn.entity.group.AbstractGroup",
>> "cluster.first.entity").attributeWhenReady("host.name")':
>> java.lang.IllegalArgumentException: Not permitted to invoke function on
>> 'class org.apache.brooklyn.core.sensor.BasicAttributeSensor' (outside
>> allowed package scope)
>>
>> Thanks
>> G
>>
>>
>>
>> From:   Mike Zaccardo <mike.zaccardo@cloudsoftcorp.com>
>> To:     Brooklyn dev <dev@brooklyn.apache.org>
>> Date:   03/22/2017 03:30 PM
>> Subject:        Re: Trouble with YAML Transformer
>>
>>
>>
>> Hi Graham,
>>
>> In your `enricher.targetValue` -- `$brooklyn.sensor` should be
>> `$brooklyn:sensor`
>> (the dot replaced by a colon).
>>
>> If that does not solve it, try providing the `enricher.targetValue` with
>> string, like so:
>>
>>       brooklyn.enrichers:
>>         - type: org.apache.brooklyn.enricher.stock.Transformer
>>           brooklyn.config:
>>             enricher.sourceSensor:
> $brooklyn:sensor("cluster.first.entity")
>>             enricher.targetSensor: $brooklyn:sensor("cluster_first_host")
>>             enricher.targetValue:
>>               $brooklyn:formatString:
>>               - "%s"
>>               -
>> $brooklyn:sensor("org.apache.brooklyn.api.entity.Entity",
>> "cluster.first.entity").attributeWhenReady("
>> host.name")
>>
>> I hope this helps.
>>
>> Cheers,
>> Mike
>>
>> On Wed, Mar 22, 2017 at 12:10 PM Graham Ashby <Graham.Ashby@ca.ibm.com>
>> wrote:
>>
>> What I want is an attribute that I can include in a template.
>> I'm trying to get the host.name of the first entity in the cluster, so
>> what I've got is:
>>
>>       brooklyn.enrichers:
>>         - type: org.apache.brooklyn.enricher.stock.Transformer
>>           brooklyn.config:
>>             enricher.sourceSensor:
> $brooklyn:sensor("cluster.first.entity")
>>             enricher.targetSensor: $brooklyn:sensor("cluster_first_host")
>>             enricher.targetValue:
>> $brooklyn.sensor("org.apache.brooklyn.api.entity.Entity",
>> "cluster.first.entity").attributeWhenReady("host.name")
>>
>> But I get the literal value
>> "$brooklyn.sensor("org.apache.brooklyn.api.entity.Entity",
>> "cluster.first.entity").attributeWhenReady("host.name")"
>>
>> So, what am I doing wrong?
>>
>> Thanks
>> Graham
>>
>> --
>>
>> Mike Zaccardo
>>
>> Senior Software Engineer
>>
>> Skype: mike.cloudsoft
>>
>> Twitter: @ItsMeMikeZ <https://twitter.com/ItsMeMikeZ> LinkedIn:
>> linkedin.com/in/mike-zaccardo
>> <https://www.linkedin.com/in/mike-zaccardo-aa3ab812>
>>
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>>
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>>
>
>
>
>
>


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