[jboss-as7-dev] problems with deployment overlays and linking

Thu Aug 30 23:29:05 EDT 2012

I have done up an initial implementation of this here https://github.com/jbossas/jboss-as/pull/2989 .

Stuart

On 24/08/2012, at 2:08 AM, Brian Stansberry <brian.stansberry at redhat.com> wrote:

> On 8/23/12 3:39 AM, Emanuel Muckenhuber wrote:
>> On 08/23/2012 01:11 AM, Brian Stansberry wrote:
>>> Sorry for the slow responses on this thread.
>>> 
>>> I think we should go with Stuart's approach, particularly if Alexey is
>>> comfortable that the CLI can support high level commands associated with it.
>>> 
>> 
>> Yeah, i am fine then as well - nevertheless some comments inline :)
>> 
> 
> Me too. ;)
> 
>>> 
>>> On 8/22/12 8:22 AM, Emanuel Muckenhuber wrote:
>>>> 
>>>> My main concern is regarding the domain mode, since the additional
>>>> linking does not seem to be necessary to me and just additional steps
>>>> mgmt clients have to take care of.
>>>> 
>>>> Whereas the deployment-scanner is a single client for standalone, which
>>>> is under our control. So i wanted to see if we there is a way we can
>>>> make this work which also satisfies your use cases.
>>>> 
>>>> I have two things in mind which i'll try to explain quickly:
>>>> 
>>>> 1) you still link the overlays as part of the <deployment />, however
>>>> the deploment-scanner is aware of that and won't remove deployments with
>>>> overlays until you use a specific invalidation marker.
>>>> 
>>> 
>>> This requires that the overlays be controlled by the scanner as well.
>>> Why? Because we don't persist the model resource for scanner-controlled
>>> deployments. So if a user linked a non-scanner-controlled overlay to a
>>> scanner controlled deployment (which seems quite rational if the overlay
>>> involves some environmental settings that never change), the link
>>> information will be lost on server reboot.
>>> 
>> 
>> I know, but that's an ancient limitation. I guess we could just start to
>> persist stuff.
>> 
> 
> We'd have to persist some association between a deployment and a scanner 
> (e.g. scanner="default" on the deployment element) and then use that to 
> indicate that the server should not auto-deploy on boot but should defer 
> to the scanner to tell it what to do. And then alter the scanner to add 
> logic for it to reconcile the state it sees in the scan directory vs 
> what the model shows.
> 
> Doable, but a fair bit of work.
> 
> I considered this before going with the "don't persist" approach. I 
> don't recall though if there was some fundamental problem with it that 
> I'm not remembering, or if it was solely that "don't persist" was doable 
> within the time constraints.
> 
>>>> 2) use overlay directories - this is more the file based approach, Where
>>>> we just pick the "deployment.name + suffix" for the overlay. So there
>>>> would be an automatic overlay/linking done by the deployment-scanner.
>>>> 
>>> 
>>> Same issue as 1).
>>> 
>> 
>> Not really. It can automatically recreate the overlays therefore it does
>> not require persistent information.
>> 
> 
> It can only recreate the association for overlays that it scans, not 
> ones that were added via CLI/console.
> 
>>>> 2.1) the overlay directory could be just a link to a virtual file (a
>>>> shared <deployment-overlay />) [1] - so in this case the overlays are
>>>> managed by the model and are not linked to the deployment lifecycle.
>>>> 
>>> 
>>> I confess I don't understand this. In particular, how does it
>>> fundamentally differ from what Stuart proposes in terms of how to
>>> organize the data?
>>> 
>> 
>> Well that is the point. It's basically the same, just that it removes
>> the requirement for the additional linking in the domain.
>> 
> 
> Ok, then I still don't understand it. If it solves a problem I'd like to 
> understand. Can you explain further?
> 
>>>> On 08/22/2012 01:03 AM, Stuart Douglas wrote:
>>>>> 
>>>>> So what are we going to do here? Personally I much prefer the idea of having this stored in the model and linking it to a deployment, so the overlay lifecycle is not tied to that of the deployment.
>>>>> 
>>>>> Another idea I had is that we could do something like define the overlays at domain level, but then define the links at server group or server level using the same name. basically something like:
>>>>> 
>>>>> /deployment-overlay=myOverlay/content=WEB-INF/web.xml
>>>>> /deployment-overlay=myOverlay/content=WEB-INF/ejb-jar.xml
>>>>> 
>>>>> /server-group=server-group1/deployment-overlay=myOverlay/deployment=test.war
>>>>> /server-group=server-group1/deployment-overlay=myOverlay/deployment=*.war
>>>>> 
>>>>> For standalone they would just be combined, similar to what I had below:
>>>>> 
>>>>> 
>>>>> /deployment-overlay=myOverlay/content=WEB-INF/web.xml
>>>>> /deployment-overlay=myOverlay/content=WEB-INF/ejb-jar.xml
>>>>> /deployment-overlay=myOverlay/deployment=test.war
>>>>> /deployment-overlay=myOverlay/deployment=*.war
>>>>> 
>>>>> 
>>>>> 
>>>>> Stuart
>>>>> 
>>>>> On 17/08/2012, at 11:03 PM, Emanuel Muckenhuber <emuckenh at redhat.com> wrote:
>>>>> 
>>>>>> 
>>>>>> On 08/17/2012 02:52 AM, Stuart Douglas wrote:
>>>>>>> The big problem with this is that it does not work with the deployment scanner.
>>>>>>> 
>>>>>> 
>>>>>> Yeah, the deployment-scanner is always a story for itself. However i think we could actually make it persist information and be aware of overlays.
>>>>>> 
>>>>>> Having overlays as part of the deployment means the lifecycle is managed together, so the deployment-scanner could define it's own invalidation policy. May it be based on whether the content got removed or we have a specific marker for that.
>>>>>> 
>>>>>> We could also think of providing a file-based overlay solution, managed by the deployment scanner only. In the end people use the deployment-scanner for a reason, so perhaps not having to worry about the model or "content" folder could be interesting. This would not even need to access persistent information though. Anyway just some ideas on the side.
>>>>>> 
>>>>>>> It also has to be specified on every re-deploy.
>>>>>> 
>>>>>> When you do a "remove" and "add" then yes. We do have specific operations to replace the content and redeploy the deployment without removing the information from the model.
>>>>>> 
>>>>>>> I think the simplest solution here
>>>>>>> is to just move the links under the deployment-overlays element and loose the
>>>>>>> flexibility to link at different levels. e.g:
>>>>>>> 
>>>>>>> /deployment-overlay=myOverlay/deployment=test.war
>>>>>>> /deployment-overlay=myOverlay/deployment=*.jar
>>>>>>> 
>>>>>> 
>>>>>> Yes, i was not really going for the simplest solution for now - this would most likely would be it :)
>>>>> 
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>>> 
>>> 
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> 
> 
> -- 
> Brian Stansberry
> Principal Software Engineer
> JBoss by Red Hat
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