[jira] [Commented] (JCLOUDS-512) Cannot start instance from newly created image in ComputeService

["Ignasi Barrera (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JCLOUDS-512?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13945871#comment-13945871 ] 

Ignasi Barrera commented on JCLOUDS-512:
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If it is a caching problem in the end, I wouldn't make more configurable the cache expiration and such internals (it can be done, but I wouldn't do that to fix this issue). Cache invalidation is quite a sensible topic and it is really hard to reach a proper configuration.

If I am not wrong, the images are only modified by the image extension, so we could add the logic to add/evict entries in the cache at that point. Instead of directly calling the extension impl we could change how the image cache is configured so it can be injected in an extension "adapter/wrapper" that would encapsulate the cache and other common logic and delegate to the provider specific extension.

If someone modifies the image list outside the scope of the compute service, we can assume the cache the compute service has can be out of sync.

> Cannot start instance from newly created image in ComputeService
> ----------------------------------------------------------------
>
>                 Key: JCLOUDS-512
>                 URL: https://issues.apache.org/jira/browse/JCLOUDS-512
>             Project: jclouds
>          Issue Type: Bug
>          Components: jclouds-compute
>    Affects Versions: 1.7.1
>            Reporter: Everett Toews
>
> A user found that after they create an image, they cannot start an instance of that image due to it not being found by the TemplateBuilder. See the example code and log in the following gist.
> https://gist.github.com/everett-toews/5447098
> I suspect the images in the TemplateBuilder are being cached and the new one isn't added to that cache but haven't been able to track down the offending code yet.
> Some notes from IRC for future work:
> in TemplateBuilderImpl images is Memoized
> the supplier is in BaseComputeServiceContextModule.supplyImageCache()
> look at the aws code
> part of it is EC2TemplateBuilderImpl.lazyImageProvider 
> it is backed by a map
> which you could listen for and invalidate the image cache entry
> if the cache interval doesn't work, it is one thing
> to express an invalidation, well there's a couple ways
> dig deep
> and monkey around with internal classes
> or expose a ListOption.invalidate()
> and code'in providers to invalidate the cache when they encounter this flag
> it's not just cache interval, it's PROPERTY_SESSION_INTERVAL. from the name it sounds like if you set it to something low it would invalidate the whole session and reauth, just to invalidate that cache.
> there's no parameter for the cache
> probably what would be most helpful is to expose a property that corresponds to CacheBuilderSpec format
> ex. images.cache-spec=expireAfterWrite=300,refreshInterval=10000
> pass that in as a property
> then people can go to town tuning without special casing everything or conflating things like session interval with cache expiry
> basically, you can see how "template" is wired in
> then re-use that approach for the caches
> the most important one being images
> so you could skip the others for now



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