Fix previously built module "leaking" file entries into subsequent build

[antonio-tomac]

I'm creating just PR without opening separate issue so I'll explain the issue here.

Consider having maven multi-module project:

parent/
   shared-lib/  (skip docker build)
   service-a/   (build image)
   service-b/   (build image)

Various layer filters are defined on parent so that both service-a and service-b inherit configuration. Now, when doing maven reactor build in order: shared-lib, service-a, service-b Final result is that:

• service-a is build as expected, every filter did it's job and resources are sliced to layers as expected
• service-b has everything that it should have + everything that service-a had in it's corresponding layers.
  • that happens because build planned file entries of service-a got "leaked" via JibLayerFilterExtension.newToLayers into subsequent module build of service-b

I'm not sure if this "leakage" is legit/desired in any scenario, if the answer is yes, then I would consider adding some configuration property (boolean) for this extension and then do clearing conditionally.

if (config.isClearFilteredLayers()) {  //better name
   newToLayers.clear();
}

[elefeint]

@antonio-tomac Thank you for the detailed description. Could you create a small reproducer project containing the project structure you've described that suffers from the leaking layers issue?

[antonio-tomac]

@elefeint sure, here it is https://github.com/antonio-tomac/jib-layer-filter-file-leak-demo

[antonio-tomac]

I've noticed that style check failed due to * import which my Intellij did without me noticing it so I reverted that change.

[elefeint]

@antonio-tomac There is a minor checkstyle issue -- could you run ./gradlew goJF to automatically fix it?

[sonarcloud[bot]]

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[antonio-tomac]

Would you be interested in sending a pull request with the fix for the same issue in jib-layer-filter-extension-gradle?

Sure, but I haven't checked how gradle behaves, maybe gradle creates new instances of plugins per every module being built so it woudn't be an issue. But I'm just guessing it at this point. I will try to reproduce it with gradle and if it suffers from issue, then I'll create PR for jib-layer-filter-extension-gradle too, or just post about my findings.

[elefeint]

I've tested it; same problem. Thank you!

[elefeint]

jib-layer-filter-extension-maven:0.3.0 released.