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Re: Rebind historic persisted state: referencing wrap:mvn bundles


Hi all,

I've opened a JIRA ticket for Aled's issue:
https://issues.apache.org/jira/browse/BROOKLYN-605

I'm also investigation his proposed solution of adding support to
class-renames here:
https://github.com/kemitix/brooklyn-server/tree/BROOKLYN-605-rebind-fails-for-historic-state

--
Paul Campbell


On Thu, 20 Sep 2018 at 14:53, Aled Sage <aled.sage@xxxxxxxxx> wrote:

> Hi all,
>
> TL;DR: I've hit a problem with rebinding to historic persisted state,
> when wrap:mvn has been used for OSGi bundles - the symbolic name
> changed, so classloading didn't work on rebind. Which of the solutions
> should we go for?
>
>
> _*PROBLEM*_
> The persisted state refers to a class in aws-java-sdk 1.11.245, but in
> my newer brooklyn I've upgraded this bundle to 1.11.411 (the old bundle
> is not there). Because this jar was added using wrap-mvn, the two
> versions of the bundle have different symbolic names! Brooklyn therefore
> doesn't know to look in the newer aws-java-sdk bundle.
>
> The bundle was added via a feature.xml containing:
>
>
> <bundle>wrap:mvn:com.amazonaws/aws-java-sdk-bundle/${aws.java.sdk.version}</bundle>
>
> When built locally, this produced a bundle with the very strange
> symbolic name:
>
>
> wrap_file__Users_aledsage_amp_cloudsoft-amp-karaf-5.2.0_system_com_amazonaws_aws-java-sdk-bundle_1.11.245_aws-java-sdk-bundle-1.11.245.jar
>
> _*EXISTING FUNCTIONALITY*_
> Brooklyn currently supports a couple of related features:
>
>  1. The persisted state will by default not include bundle versions. We
>     are therefore willing to use newer versions of a given bundle.
>  2. When adding your own bundle, you can include metadata in it's
>     MANIFST.mf to say what bundle/version it replaces.
>     See brooklyn-docs guide/ops/upgrades/_blueprints.md
>
> However, I don't want to use (2) because that would involve fiddling
> with the wrap:mvn to add more metadata.
>
>
> _*POSSIBLE SOLUTIONS*_
> There are no doubt many ways to solve this problem. I describe a few of
> them below.
>
> I think I favour the class-renames approach because of its simplicity.
>
> *_Add support to class-renames_*
> Our deserializingClassRenames.properties allows rebind to handle class
> renames, or a specific class moving from one bundle to another. This is
> useful for historic persisted state.
>
> We could add support for bundle wildcards, to say that all classes in
> one bundle can be loaded from another bundle.
>
> For example:
>
>      wrap_blah_aws-java-sdk-bundle-1.11.245.jar\:*  :
> wrap_blah_aws-java-sdk-bundle-1.11.411.jar\:*
>
> *_Support a bundle-upgrade configuration file_*
> We could add support for a config file that gives explicit named bundle
> replacements. This would augment the existing functionality (2 above),
> but instead of the replacement bundle being defined in the new bundle's
> metadata, it could also be defined in this configuration file.
>
> For example, $BROOKLYN_HOME/etc/org.apache.brooklyn.bundleupgrade.cfg
> could contain something like:
>
>      wrap_blah_aws-java-sdk-bundle-1.11.411.jar:
>        Brooklyn-Catalog-Upgrade-For-Bundles:
> "wrap_blah_aws-java-sdk-bundle-1.11.245.jar: *"
>
> (would need to figure out the cfg versus yaml format here, obviously!)
>
> *_Recognise 'wrap' bundles, and allow newer versions_*
> When loading the class, we could recognise the "wrap_" prefix. We could
> figure out from the symbolic name what it was built from, and be willing
> to use bundles that are newer versions.
>
> However, playing with wrap:mvn, the bundle naming is not as obvious as
> one would expect. The symbolic name below is a very different structure
> from that above:
>
>
> wrap_mvn_com.example.brooklyn.test.resources.osgi_brooklyn-test-osgi-com-example-plainoldjar_1.0.0
>
> This example was created in karaf client by running:
>
>      bundle:install
>
> wrap:mvn:com.example.brooklyn.test.resources.osgi/brooklyn-test-osgi-com-example-plainoldjar/1.0.0
>
> See brooklyn-server's
> org.apache.brooklyn.util.core.ClassLoaderUtils.tryLoadFromBundle.
>
> *_Require users to set the symbolic name, when using wrap:mvn_*
> We could require users to *not* use the simple "wrap:mvn", and instead
> force them to ensure a more predictable symbolic name + version is used.
>
> However, that sounds harder for users. It also doesn't solve the problem
> for anyone with such historic persisted state.
>
>
> _*LONG TERM / DOCS
> *_We should warn people about this in our docs, including a description
> of how to work around it.
>
> We should discourage the use of complex types in config keys and
> sensors, where we (or the user) don't explicitly control the versioning
> and schema of those types.
>
> **_**_
>


-- 
Paul Campbell
Software Engineer
*Cloudsoft <https://cloudsoft.io/> *| Bringing Business to the Cloud

E: paul.campbell@xxxxxxxxxxxx
M: 07476981644 <+447476981644>
T: kemitixcode <https://twitter.com/kemitixcode>
L: https://www.linkedin.com/in/paulkcampbell/

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